UNIVERSIDADE FEDERAL DE OURO PRETOESCOLA DE MINAS

CURSO DE PÓS-GRADUAÇÃO EM ENGENHARIA CIVIL

Dissertação de Mestrado

AVALIAÇÃO COMPORTAMENTAL DE JUNTAS SOLDADAS DEUM AÇO ESTRUTURAL DO TIPO SAC 50 SOB FADIGA

Autor: José Geraldo Araújo Silva

Orientador: Luiz Cláudio Cândido

Setembro de 2001

ii

José Geraldo Araújo Silva

AVALIAÇÃO COMPORTAMENTAL DE JUNTAS SOLDADAS DE UM AÇOESTRUTURAL DO TIPO SAC 50 SOB FADIGA

Dissertação de Mestrado apresentada ao Curso de Pós-Graduação em Estrutura Metálica

do Departamento de Engenharia Civil, da Escola de Minas, da Universidade Federal de

Ouro Preto

Área de concentração: Estruturas Metálicas

Orientador: Prof. Luiz Cláudio Cândido

Ouro Preto

2001

iii

Dissertação apresentada ao Curso de Pós-Graduação em Estrutura Metálica do

Departamento de Engenharia Civil, da Escola de Minas, da Universidade Federal de

Ouro Preto, como parte dos requisitos para obtenção do título de Mestre em Engenharia

Civil

__________________________________________ Prof. Dr. Luiz Cláudio Cândido - Orientador Universidade Federal de Ouro Preto (UFOP)

__________________________________________ Prof. Dr. Leonardo Barbosa Godefroid - Co-orientador

Universidade Federal de Ouro Preto (UFOP)

________________________________________ Prof. Dr. Carlos Alberto Cimini Júnior

Universidade Federal de Minas Gerais (UFMG)

________________________________________ Prof. Dr. Marcílio Sousa Rocha Freitas

Universidade Federal de Ouro Preto (UFOP)

________________________________________ M.Sc. Geraldo de Paula Martins

Centro de Desenvolvimento de Tecnologia Nuclear (CDTN/CNEN)

iv

AGRADECIMENTOS

A Deus, por todas as pessoas que Ele colocou no meu caminho.

v

RESUMO

Este trabalho apresenta o estudo do comportamento de juntas soldadas de um aço

estrutural, do tipo SAC 50, sob fadiga. O material foi soldado através do emprego do

processo ao arco elétrico com eletrodo revestido. Além dos ensaios mecânicos

tradicionais, aplicou-se metodologias da Mecânica de Fratura, através de ensaios de

tenacidade à fratura (COD e Integral J), e ensaios de propagação de trincas por fadiga.

Avaliou-se as características comportamentais das três regiões do material: zona

fundida, zona termicamente afetada e metal base. Verificou-se, em termos de tenacidade,

que as três regiões do material, pelo efeito da soldagem, apresentaram comportamento

semelhante. Correlacionou-se os valores obtidos nos ensaios de tenacidade com ensaios

de impacto Charpy. A zona fundida apresentou valor de COD, δm, maior que a zona

termicamente afetada e o metal base, o que significa maior resistência à propagação de

trincas. O efeito do fator R não influenciou significativamente o posicionamento das

curvas de propagação de trinca por fadiga na região II. No entanto, para R = 0,7, o valor

limiar (threshold), ∆Kth, sofreu uma alteração significativa, diminuindo para o caso do

metal base. Pôde-se verificar, também, que para o ensaio de propagação de trinca por

fadiga, o valor limiar, para o metal base foi inferior às outras regiões do CP,

caracterizando um pior desempenho. A partir do ensaio de Integral J pôde-se estimar um

valor de JQ para o metal base. E ainda, fez-se análises microfractográficas dos CPs

ensaiados. Verificou-se o aspecto dúctil das fraturas do material, através de “dimples”.

No entanto, para ensaios de impacto Charpy, em ‘baixas” temperaturas, o material

apresentou o aspecto frágil das fraturas através da presença de facetas de clivagem.

vi

ABSTRACT

This work studied the behavior of welded joints of structural steel type “SAC 50” under

fatigue. The material was welded using the process of electric arc with coated electrodes.

Besides using the traditional mechanical tests, methods of fractures mechanics were

applied through tests of fracture resistance (COD and J integral) and of the fatigue crack

propagation. The behavioral features of three areas of interest (cast zone, heat affected

zone and base metal) were determined. In terms of strength, the conclusions were that

the three areas presented similar behavior considering the welding effect. The values

obtained from resistance tests were later related to those from Charpy impact tests. The

cast zone presented a higher COD value than the base metal i.e. higher fracture

toughness. The effect of the R factor did not present a strong influence in the position of

the fatigue crack propagation curves caused by fatigue. However, for R = 0.7, the

threshold value (∆Kth), was slightly altered, being reduced in the case of the base metal.

For the fatigue crack propagation test, the threshold value for the base metal was lower

than that in the another areas of the specimens, indicating a worse performance.

Considering the J integral test, it is possible to estimate a JQ value for the base metal.

Also, microfractography analyses of specimen were made. The ductile aspect of the

material fractures was revealed by the existence of dimples, although, for the Charpy

impact test performed under low temperature, the brittle aspect was revealed by

cleavage.

vii

SUMÁRIO

1. INTRODUÇÃO .........................................................................................................1

2. OBJETIVOS ..............................................................................................................3

3. RELEVÂNCIA DO TRABALHO ...........................................................................4

4. REVISÃO BILIOGRÁFICA ....................................................................................5

4.1 – Introdução à Soldagem ...................................................................................5

4.1.1 – Definição/Caracterização .......................................................................5

4.1.2 – Histórico ...................................................................................................6

4.2 – Principais Processos Convencionais de Soldagem .......................................9

4.2.1 – Soldagem com eletrodo revestido ..........................................................9

4.2.2 – Soldagem com proteção gasosa ............................................................12

4.2.3 – Soldagem por arco submerso ...............................................................15

4.3 – Aço Estrutural ...............................................................................................16

4.3.1 – Histórico .................................................................................................20

4.3.2 – Aços patináveis ......................................................................................21

4.4 – Fundamentos da Fadiga ...............................................................................25

4.4.1 – Histórico .................................................................................................26

4.4.2 – Aspectos básicos da fadiga ....................................................................27

4.4.3 – O processo de fadiga .............................................................................32

4.4.3.1 – Início do processo de fadiga .....................................................33

4.4.3.2 – Propagação da trinca de fadiga..................................................35

4.5 – Fundamentos da Mecânica de Fratura .......................................................36

4.5.1 – Histórico .................................................................................................36

4.5.2 – Generalidades ........................................................................................40

4.5.3 – Fator de intensidade de tensão ............................................................42

4.5.4 – Tenacidade à fratura (KIC.) .................................................................46

4.5.5 – Estado plano de deformação versus estado plano de

tensão.................................................................................................. 48

4.5.6 – Integral J ................................................................................................49

4.5.7 – Abertura de trinca (CTOD) .................................................................51

4.5.8 - Aplicação da Mecânica de Fratura em fadiga .....................................52

viii

5. MATERIAIS E MÉTODOS ................................................................................. 56

5.1 – Materiais ....................................................................................................... 56

5.2 – Métodos ..........................................................................................................61

5.2.1 – Soldagem do material ...........................................................................62

5.2.2 – Obtenção da pré-trinca de fadiga ........................................................63

5.2.3 – Ensaios de propagação de trinca por fadiga

(da/dN) x ∆∆∆∆K...........................................................................................63

5.2.4 – Ensaios de impacto Charpy ..................................................................63

5.2.5 – Ensaios de Kc e δδδδm .................................................................................64

5.2.6 – Ensaios de integral J .............................................................................65

5.2.7 – Análise de falhas ...................................................................................65

6. RESULTADOS E DISCUSSÃO ............................................................................66

6.1 – Ensaios de tração ..........................................................................................66

6.2 – Ensaios de impacto Charpy ..........................................................................66

6.3 – Ensaios de microdureza ................................................................................69

6.4 - Ensaios de tenacidade à fratura .................................................................. 70

6.5 – Ensaios de integral J .....................................................................................73

6.6 – Ensaios de propagação de trincas (fadiga) .................................................76

6.7 – Análise de fraturas ........................................................................................78

6.7.1 – Microfractografias de CPS ensaiados em impacto Charpy ..............79

6.7.2 – Microfractografias de CPs ensaiados em tenacidade à fratura ....... 81

6.7.3 - Microfractografias de CPs ensaiados à fadiga ................................... 85

7. CONCLUSÕES .......................................................................................................86

8. SUGESTÕES PARA FUTUROS TRABALHOS ................................................ 87

9. REFERÊNCIAS BIBLIOGRÁFICAS ................................................................ 88

ix

LISTA DE FIGURAS

Figura 4.1 – Evolução dos processos de soldagem ao longo do tempo ............................9

Figura 4.2 – Soldagem por eletrodo revestido ................................................................10

Figura 4.3 – Processo de soldagem TIG ..........................................................................13

Figura 4.4 – Processo de soldagem MIG/MAG ..............................................................14

Figura 4.5 – Processo de soldagem por arco submerso ...................................................15

Figura 4.6 – Curvas tensão x deformação para diferentes classes de aços ......................17

Figura 4.7 – Perda de espessura em ambiente industrial agressivo .................................22

Figura 4.8 – Prefeitura de Salvador/BA; aço do tipo SAC 41, sem pintura ...................24

Figura 4.9 – Escola de Minas – Campus UFOP/ Ouro Preto .........................................25

Figura 4.10 – Representação esquemática de uma superfície de fratura por fadiga;

1- fratura instável final; 2 - marcas de praia; 3 - região de início .........28

Figura 4.11 – Tipos de tensões cíclicas ...........................................................................29

Figura 4.12 – Curva de Wöhler .......................................................................................30

Figura 4.13 – Esquema de ensaio de uma viga em escala real ........................................33

Figura 4.14 – Montagem de um corpo-de-prova do tipo tração-compacto .....................34

Figura 4.15 – Resultado típico do ensaio fadiga S-N mostrando o limite de fadiga .......35

Figura 4.16 – Propagação para uma trinca de fadiga ......................................................36

Figura 4.17 – Navio Liberty rompido por fratura frágil ..................................................41

Figura 4.18 – Placa infinita com uma trinca de largura 2a .............................................42

Figura 4.19 – Sistema de coordenadas ............................................................................42

Figura 4.20 – Estado de tensão na vizinhança de uma trinca ..........................................43

Figura 4.21 – Modos de deformação ...............................................................................44

Figura 4.22 – Linhas de força de uma barra entalhada ensaiada à tração .......................46

Figura 4.23 – Variação do fator de intensidade de tensão versus espessura ...................47

Figura 4.24 – Origens dos efeitos de constrição .............................................................48

Figura 4.25 – Figura 4.25 – Ilustração do embotamento na ponta da trinca ...................52

Figura 4.26 – Tipo de corpo-de-prova (a); dados de ensaio (b); curva da/dN x ∆K (c)..53

Figura 4.27 – Comportamento do crescimento de trincas em metais .............................54

Figura 5.1 – Fotomicrografias das três zonas estabelecidas na soldagem (ataque com

nital 3%, aumento de 100X) ......................................................................58

x

Figura 5.2 – Fotomicrografias do material estudado: zona fundida (a), zona termicamnte

afetada (b) e metal base (c). Ataque com nital 3%; aumento de 500X.......59

Figura 5.3 – Representação esquemática de como os CPs foram retirados para ensaio .60

Figura 5.4 – Corpo-de-prova utilizado (tipo tração-compacto, ASTM E 399/90) ..........60

Figura 5.5 – Máquina de eletro-erosão para confecção dos entalhes nos CPs para ensaios

de fadiga .....................................................................................................61

Figura 5.6 – Vista geral da máquina servohidráulica, MTS 10t, para ensaios de

tenacidade à fratura e fadiga ....................................................................62

Figura 5.7 – Posicionamento dos entalhes em corpo-de-prova para enaios Charpy; (a)

entalhe ao longo da espessura (orientação T-S); (b) entalhe ao longo do

cordão de solda (orientação T-L). As setas indicam a direção da espessura;

dimensões do CP (em mm): 10 x 10 x 55 ..................................................64

Figura 5.8 – Posicionamento de clipe gage para medição de CTOD .............................64

Figura 6.1 – Curva de energia absorvida em ensaio de impacto na região da ZTA;

entalhe ao longo da espessura (MARTINS et alli, 2001).........................67

Figura 6.2 – Curva de energia absorvida em ensaio de impacto na região da ZTA com

entalhe ao longo do cordão de solda. (MARTINS et alli, 2001)................67

Figura 6.3 – Figura 6.3 – Perfil de microdureza do material ensaiado (MARTINS et alli,

2001) ..........................................................................................................69

Figura 6.4 – Localização dos pontos para ensaio de microdureza (MARTINS et alli,

2001) ............................................................................................................70

Figura 6.5 – Ensaio de tenacidade à fratura, corpo-de-prova com orientação T-L,

entalhe no metal de base ..........................................................................71

Figura 6.6 – Ensaio de tenacidade à fratura, CP com orientação T-L, entalhe na zona fun-

dida (metal de solda) ...................................................................................71

Figura 6.7 – Ensaio de tenacidade à fratura, CP com orientação T-L, entalhe na zona

termicamente afetada .................................................................................72

Figura 6.8 – Curva de carga versus COD para o metal base ...........................................74

Figura 6.9 – Curva de integral J para o metal base .........................................................75

Figura 6.10 – Curva da/dN versus ∆K para metal de base, zona termicamente

afetada e zona fundida; R = 0,3; f = 30 Hz ..............................................76

Figura 6.11 – Curva da/dN versus ∆K para metal de base, zona termicamente afetada

e zona fundida; R = 0,7; f = 30 Hz ..........................................................77

xi

Figura 6.12 – Curva da/dN versus ∆K para metal de base, zona termicamente afetada e

zona fundida; R = 0,7 e 0,3; f = 30 Hz ......................................................77

Figura 6.13 – Microfractografia do material na região da ZTA; entalhe ao longo do

cordão de solda; -197oC; facetas de clivagem; aumento de 750X

(MEV).......................................................................................................79

Figura 6.14 – Idem à Figura 6.13; aumento de 1500X (MEV) ......................................79

Figura 6.15 – Microfractografia do material na região da ZTA; entalhe ao longo do

cordão de solda; 0oC; fratura semi-frágil; aumento de 750X (MEV).........79

Figura 6.16 – Idem à Figura 6.15; 1 - dimples; 2 - facetas de clivagem; aumento de

2000X (MEV) ..........................................................................................79

Figura 6.17 – Microfractografia do material na região da ZTA; entalhe ao longo da

espessura; -85oC; fratura semi-frágil; aumento de 750X (MEV) ............79

Figura 6.18 – Idem à Figura 6.17; aumento de 1500X (MEV) .......................................80

Figura 6.19 – Microfractografia do material na região da ZTA; entalhe ao longo da

espessura; -5oC; fratura semi-frágil; aumento de 750X (MEV) ..............80

Figura 6.20 – Idem à Figura 6.17; aumento de 1500X (MEV) .......................................80

Figura 6.21 – Microfractografia de CP empregado no ensaio de tenacidade; entalhe na

ZF; região da pré-trinca de fadiga; aumento de 1000X (MEV) ..............81

Figura 6.22 – Microfractografia de CP empregado no ensaio de tenacidade; entalhe na

ZF; fratura dúctil; aumento de 1000X ( MEV) ........................................81

Figura 6.23 – Detalhe da Figura 6.22, presença de partícula, caracterizando um dimple;

aumento de 5000X (MEV) ......................................................................81

Figura 6.24 – Microfractografia de CP ensaiado em tenacidade à fratura; entalhe na

ZTA; região da pré-trinca de fadiga; aumento de 1000X (MEV) ..........82

Figura 6.25 – Microfractografia de CP ensaiado em tenacidade à fratura; entalhe na

ZTA; região de transição entre a pré-trinca de fadiga e a fratura; aumento

de 200X (MEV) .......................................................................................82

Figura 6.26 – Microfractografia de CP ensaiado em tenacidade à fratura; entalhe na

ZTA; região de fratura; aumento de 100X (MEV) ..................................82

Figura 6.27 – Microfractografia de CP ensaiado em tenacidade à fratura; entalhe na

ZTA; fratura dúctil; aumento de 1000X (MEV) ......................................83

Figura 6.28 - Detalhe da Figura 6.27; presença de partícula; aumento de 1500X

(MEV).......................................................................................................83

xii

Figura 6.29 - Microfractografia de CP ensaiado em tenacidade à fratura; entalhe no MB;

região da pré-trinca de fadiga; aumento de 1000X (MEV)........................83

Figura 6.30 – Microfractografia de CP ensaiado em tenacidade à fratura; entalhe no

MB; região de transição entre a pré-trinca de fadiga e a fratura; aumento

de 200X ....................................................................................................83

Figura 6.31 – Microfractografia de CP ensaiado em tenacidade à fratura; entalhe no MB;

região da fratura; aumento de 100X (MEV) ............................................84

Figura 6.32 – Microfractografia de CP ensaiado em tenacidade à fratura; entalhe no MB;

fratura dúctil; aumento de 1000X (MEV) ................................................84

Figura 6.33 – Detalhe da Figura 6.30; presença de partícula; aumento de 1500X

(MEV).......................................................................................................84

Figura 6.34 – Microfractografia de CP ensaiado à fadiga; entalhe no MB; região de

fratura do CP; aumento de 500X (MEV) .................................................85

Figura 6.35 – Microfractografia de CP ensaiado à fadiga; entalhe na ZTA; região de

fratura do CP; aumento de 500X (MEV) .................................................85

Figura 6.36 – Microfractografia de CP ensaiados à fadiga; entalhe na ZF; região de

fratura do CP; aumento de 500X (MEV) ................................................85

xiii

LISTA DE TABELAS

Tabela 4.1 – Resultados típicos para um aço estrutural submetido a ensaio de fadiga com

inversão de carregamento, R = - 1 .............................................................34

Tabela 5.1 – Propriedades mecânicas do aço tipo SAC-50 .............................................56

Tabela 5.2 – Composição química do aço tipo SAC-50 (% do peso) - USIMINAS

(1999) .......................................................................................................56

Tabela 5.3 – Composição química nominal do eletrodo E7018 (% do peso) .................57

Tabela 5.4 – Composição química da zona fundida (% do peso) ...................................57

Tabela 5.5 – Propriedades mecânicas do aço tipo SAC-50 .............................................57

Tabela 5.6 – Parâmetros utilizados na abertura da pré-trinca e ensaio de propagação de

trinca ...........................................................................................................63

Tabela 6.1 – Energia absorvida em ensaios de impacto, Charpy, a 25oC .......................68

Tabela 6.2 – Valores aproximados de tenacidade à fratura KC (orientação T-L) ............70

Tabela 6.3 – Tenacidade à fratura δm (orientação T-L) ...................................................73

xiv

NOMENCLATURA E ABREVIATURAS

A: Área

a: Comprimento de trinca

ao: Comprimento inicial de trinca

AASHTO: American Association of State Highway of Transportation Officials

AISC: American Institute of Steel Construction

ASME: American Society of Mechanical Engineers

ASTM: American Society Testing Materials

AWS: American Welding Society

B: Espessura do corpo-de-prova

CDTN: Centro de Desenvolvimento da Tecnologia Nuclear

CNEN: Comissão Nacional de Energia Nuclear

COD: Crack open displacement

CP: Corpo-de-prova

CTOD: Crack tip opening displacement

CVN: Energia absorvida em CP entalhado

da/dN: Taxa de crescimento de trinca por fadiga

E: Módulo de elasticidade (Young)

EPD: Estado plano de deformação

EPT: Estado plano de tensão

I: Corrente de soldagem

J: Integral J

Ji: Integral J para início de crescimento estável da trinca

JIC: Valor crítico da integral J para modo I

Je: Integral J avaliada na região elástica

Jp: Integral J avaliada na região plástica

K: Fator de intensidade de tensão

KIC: Fator de intensidade de tensão crítico para modo I, no EPD

KJC: Fator de intensidade de tensão crítico para modo I, calculado a partir de JIC

KI: Fator de intensidade de tensão para o modo I

xv

Kmin: Valor limiar para tenacidade à fratura

L: Comprimento do corpo-de-prova

MAG: Metal active gas

MB: Metal base

MEV: Microscópio eletrônico de varredura

MIG: Metal inert gas

MLEF: Mecânica linear elástica de fratura

MPa: Mega Pascal, unidade de tensão

MTS: Metal testing system

R: Relação entre tensões σmín e σmáx

SAC: Soldável anticorrosivo

TIG: Tungsten inert gas

ZF: Zona fundida

W: Largura do corpo-de-prova

ZTA: Zona termicamente afetada

ν: Coeficiente de Poisson

σys: Limite de escoamento

σmáx: Tensão máxima

σmín: Tensão mínima

σav: Tensão média

σsr: Amplitude de tensões

δ: Valor do COD

δi: Valor do COD no início de crescimento estável da trinca

ε: Deformação (%)

∆Kth: Valor limiar de ∆K

σx: Tensão normal na direção do eixo x

σy: Tensão normal na direção do eixo y

σz: Tensão normal na direção do eixo z

τxy: Tensão cisalhante paralela ao plano xy

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4.2 -$Principais Processos Convencionais de Soldagem

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4.2.1 - Soldagem com eletrodo revestido

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4.2.2 - Soldagem com proteção gasosa

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2,#'/$./$8K1*/7$(%3)(9&G#($-/)%&1%(-'($/$&)9F-*/>$e,&-'/$&/#$(1(')/./#$,'*1*I&./#7$(1(#

3/.(%$#()$2/-#,%AB(*#$/,$-0/$2/-#,%AB(*#>

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Z-')($ /#$ 3)/2(##/#$ 2/-8(2*./#$ '(%/#$ /$ ^Qu$ PTungsten Inert GasU7$XQu$ PMetal Inert

GasU$($/$XEu$PMetal Active GasU>$E$#(9,*)$.*#2/))()G#(G@$#,2*-'&%(-'($#/C)($2&.&$,%

.(1(#>

J)/2(##/$^Qu

b$,%$3)/2(##/$.($ #/1.&9(%$+,($ 4/*$ 3&'(-'(&./$ -&$ .K2&.&$ .($ aO$ -/#$Z#'&./#$W-*./#7

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4.2.3 - Soldagem por arco submerso

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4.3 -$Aço Estrutural

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56

!"#"$%&'()%)*"'"$+&,-,*

Serão descritos neste item os materiais e a metodologia utilizados para a realização dos

ensaios.

!./"#"$01234045

A partir das chapas de aço estrutural anticorrosivo do tipo SAC-50, com 12 mm de

espessura, soldou-se ao arco elétrico com eletrodo revestido (E-7018) para avaliar as

características do material através do ensaio de fadiga. Realizou-se a caracterização

química e mecânica onde os valores encontram-se nas Tabelas 5.1-5.4 e 5.5

respectivamente.

A Tabela 5.1 apresenta a composição química do material utilizado, obtida no

laboratório da empresa VDL (Valadares Diesel Ltda) de Itabirito/MG.

Tabela 5.1 - Composição química do aço tipo SAC-50 (% peso)

Elemento C Mn Si P S Ni Cr

Composição 0,14 1,15 0,37 0,04 0,02 0,18 0,39

A Tabela 5.2 mostra a composição química nominal do material, segundo o catálogo da

USIMINAS (1999).

Tabela 5.2 - Composição química do aço tipo SAC-50 (% do peso) - USIMINAS (1999)

Elemento C Mn Si P S Ti Cr Cu Nb

Composição 0,18 1,50 0,15-0,55 0,03 0,025 0,15 0,40-0,65 0,25-0,50 0,050

O eletrodo para soldagem utilizado foi o tipo E7018, cuja composição química nominal,

segundo a ESAB (2001), é apresentada na Tabela 5.3.

57

Tabela 5.3 - Composição química nominal do eletrodo E7018 (% peso)

Elemento C Mn Si P S Ni Cu

Composição 0,07 1,00 0,30 ---- ---- 0,18 0,45

Analisou-se quimicamente a zona fundida nos laboratórios da VDL e os resultados são

apresentados na Tabela 5.4.

Tabela 5.4 - Composição química da zona fundida (% peso)

Elemento C Mn Si P S Ni Cr

Composição 0,12 1,20 0,42 0,06 0,02 0,89 0,11

Tabela 5.5 - Propriedades mecânicas do aço tipo SAC-50

Limite de

Escoamento (MPa)

Limite de

Resistência (MPa)

Deformação

(%)

385 495 24

Segundo a Usiminas (1999), fabricante deste tipo de aço, os valores para a resistência

são:

- Limite de escoamento: 360 MPa

- Limite de resistência: 485 Mpa

Caracterizou-se o material, onde fez-se o perfil de microdureza da junta soldada,

analizando-se as diversas regiões, mapeando as amostras a partir do metal base,

passando pela zona termicamente afetada e finalizando na zona fundida.

Para análise metalográfica, uma amostra da chapa contendo a zona fundida (ZF), zona

termicamente afetada (ZTA), e metal base (MB) foi analisada no Laboratório de

Metalografia do Departamento de Engenharia Metalúrgica e de Materiais (DEMET) da

58

Escola de Minas/UFOP, onde a mesma foi lixada até a lixa de granulometria número

600 e polida em alumina. As Figuras 5.1 e 5.2 mostram as microestruturas das três zonas

(ZF, ZTA, MB), podendo-se ver as diferenças nos tamanhos dos grãos das três regiões.

6&%"""""""""""""""""""""""""""""""""""""""""""$7""""""""""""""""""68""""""""""""""""""""""""""""""""""""""""""""""6&%

Figura 5.1 - Fotomicrografias das três zonas estabelecidas na soldagem (ataque com nital

3%; aumento de 100X)

Os CPs para ensaios de fadiga foram retirados das chapas no sentido L-T, conforme

Figura 5.3. Estão indicados ainda nesta figura o local da soldagem e a posição de

retirada dos CPs para ensaio de tração.

As amostras foram retificadas, pois a região da ZF ficou irregular em relação às zonas

não fundidas. Com isso, de certa forma, diminuiu-se a espessura original das chapas.

Confeccionou-se os CPs com entalhes direcionados segundo as áreas de interesse (ZTA,

ZF e MB). Lixou-se as amostras até a lixa número 600, onde posteriormente foram

polidas; em seguida, atacou-se com nital a 3% para diferenciação das zonas de interesse

e então pôde-se cortar os CPs para posicionamento dos entalhes dentro das medidas

normativas. A Figura 5.4 mostra o CP do tipo tração-compacto, para ensaio de fadiga,

empregado neste trabalho. As dimensões foram estabelecidas de acordo com a norma

ASTM E399/90.

59

(a)

(b)

(c)

Figura 5.2 - Fotomicrografias do material estudado: zona fundida (a), zona termicamente

afetada (b) e metal base (c) – estrutura ferrita (branco) e perlita (escuro).

Ataque com nital 3%; aumento de 500X

60

""""

Figura 5.3 - Representação esquemática de como os CPs foram retirados para os ensaios

Figura 5.4 - Corpo-de-prova utilizado (tipo tração-compacto, ASTM E 399/90)

TRAÇÃO NA SOLDA

60°

790 131

238

143 480

152

165

59

200

203

356

446

921

960

480143

238

200

200

59

152

165

61

!.9"#"$:1;<;5

Para confecção dos entalhes nos CPs, utilizou-se uma máquina de eletro-erosão de

eletrodo fixo (Figura 5.5), com tensão de 90V e corrente de 30A.

Para os ensaios de tenacidade à fratura e fadiga utilizou-se uma máquina

servohidráulica, MTS (Metal Testing System), de 10t, acoplada a um computador com

um software específico, onde foram registrados os dados, conforme está mostrado na

Figura 5.6.

Figura 5.5 - Máquina de eletroerosão para confecção dos entalhes nos CPs para ensaios

de fadiga

62

Figura 5.6 - Vista geral da máquina servohidráulica, MTS 10t, para ensaios de

tenacidade à fratura e fadiga

!.9./"#"*;=<0>2?"<;"?012340=

A soldagem foi realizada no Centro de Desenvolvimento da Tecnologia Nuclear

(CDTN) - Comissão Nacional de Energia Nuclear (CNEN, Belo Horizonte), sendo

adotada a seguinte especificação do procedimento de soldagem:

- Corrente: 130 Ampéres

- Tensão: 22 Volts

- Número de passes: 6

- Velocidade de soldagem: 300mm/minuto

- Pré-aquecimento: 50oC

- Pós-aquecimento: não houve

- Descrição do eletrodo: E7018, diâmetro 5mm

- Chanfros: em 1/2V

63

!.9.9"#",@12ABC;"<0"D3:#134AE0"<2"F0<4>0

Fez-se pré-trincas nos CPs para ensaios de tenacidade à fratura, KIC, e ensaios de

propagação de trinca (fadiga) adotando-se os preceitos da norma ASTM E 813/89.

Utilizando a máquina servohidráulica e adotando-se os parâmetros apresentados na

Tabela 5.6, obteve-se as pré-trincas.

Tabela 5.6 - Parâmetros utilizados na abertura da pré-trinca e ensaio de propagação de

trinca

Parâmetros/variáveis R = 0,3 R = 0,7

Freqüência (Hz) 30 30

Carga (N) 350 a 1160 1770 a 2530

Comprimento (mm) 13 13

Kmáx ( mMPa ) 20 20

!.9.G"#"'A504;5"<2"D3;D0>0BC;"<2"134AE0"D;3"F0<4>0"H<aI<JK"L"MN

Após a"obtenção de pré-trincas, os CPs foram ensaiados para avaliação de propagação

de trincas. Os parâmetros utilizados durante estes ensaios são apresentados na

Tabela 5.6.

!.9.O"#"'A504;5"<2"4?D0E1;"PQ03DR

A partir de CPs de ensaios de impacto, do tipo Charpy, com entalhe em V, foram

realizados ensaios onde registrou-se a energia absorvida versus temperatura na região da

ZTA, nas direções da espessura e longitudinalmente, sendo que esta metodologia está de

acordo com o proposto por YOUNG (1989). A Figura 5.7 apresenta a posição do entalhe

nos CPs.

64

Figura 5.7 - Posicionamento dos entalhes em corpos-de-prova para ensaios Charpy; (a)

entalhe ao longo da espessura; (b) entalhe ao longo do cordão de solda. As

setas indicam a direção da espessura; dimensões do CP (em mm): 10x10x55

!.9.!"#"'A504;5"<2"NE"2"δδδδ?

Realizou-se ensaios de tenacidade à fratura na máquina servohidráulica e pelos valores

obtidos através do clip gage, posicionado nos CPs conforme mostra a Figura 5.8, pôde-

se medir o deslocamento de abertura na ponta da trinca (CTOD).

Figura 5.8 - Posicionamento do clip gage para medição de CTOD

65

!.9.S"#"'A504;5"<2")A12>30="T

Mesmo considerando que este tópico não era objeto deste trabalho, fez-se um ensaio de

Integral J, para avaliar o comportamento do metal base. Utilizou-se a técnica de um

único CP, que usa a determinação da compliance (inverso da rigidez). Registrou-se,

inicialmente, a curva carga aplicada versus o deslocamento (flecha) da linha de carga. O

comprimento de trinca é calculado em intervalos regulares durante o ensaio, através de

descarregamentos parciais e de medição da compliance. Obteve-se, também, a curva

variação de J com a extensão de trinca, onde estimou-se um valor de tenacidade, JQ.

!.9.U"#"%AV=452"<2"F0=Q05

Fez-se análises microfractográficas das amostras ensaiadas, empregando-se o

microscópio eletrônico de varredura (MEV), do CDTN/CNEN. Analisou-se também

macrofractograficamente os CPs, utilizando-se um estereoscópio acoplado a um

microscópio ótico quantitativo.

__

6. RESULTADOS E DISCUSSÃO

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%(#%/#>

6.1 - Ensaios de tração

"CD('*B&-./$2&)&2'()*I&)$/$%(2&-*2&%(-'($/$%&'()*&17$)(&1*I/,G#($/#$(-#&*/#$.($')&50/>

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HJ#$/2/))(,$-/$XV7$%/#')&-./$2/%$*##/$&$+,&1*.&.($.&$#/1.&$+,($4/*$(M(2,'&.&>

6.2 - Ensaios de impacto Charpy

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P&3)/M*%&.&%(-'($GaY/HU>

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-250$ -200$ -150$ -100$ -50$ 0$ 50$ 100$ 150$ 200$

0$

20$

40$

60$

80$

100$

120$

140$ $

Equação da curva:$y=57,717+59,939*tanh[(x+2,166)/60]$Coeficiente de Correlação (R)=0,97398$

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Temperatura (ºC)$g*9,)&$ _>!$ G$ H,)B&$ .($ (-()9*&$ &C#/)B*.&$ (%$ (-#&*/$ .($ *%3&2'/$ -&$ )(9*0/$ .&$ w^E`

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-250$ -200$ -150$ -100$ -50$ 0$ 50$ 100$ 150$ 200

0$

20$

40$

60$

80$

$

Equação da curva:$y=34,094+33,801*tanh[(x+34,094)/45]$Coeficiente de correlação(R)=0,9882$

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6.3 - Ensaios de microdureza

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$6.4 - Ensaios de tenacidade à fratura

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9&)&-'*)$ /$ZJL$ P(#'&./$ 31&-/$ .($ .(4/)%&50/U7$a

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E#$2,)B&#$/)*9*-&.&#$&')&BK#$./#$(-#&*/#$.($4&.*9&$2/%$&#$)(#3(2'*B&#$)(1&56(#$.($2&)9&

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2,)B&#$.($&2/)./$2/%$&#$)(1&56(#$.($2&)9&#$&31*2&.&#$P4&'/)$dU>

1 10 1001E-7

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Delta K (MPa*m^1/2)

g*9,)&$ _>!O$ G$ H,)B&$ .al.?$ versus$ ∆v$ 3&)&$ %('&1$ .($ C&#(7$ I/-&$ '()%*2&%(-'(

&4('&.&$($I/-&$4,-.*.&`$d$�$O7N`$4$�$NO$qI

ff

1$ 10$ 100$1E-7$

1E-6$

1E-5$

1E-4$

1E-3$

0,01$

R = 0,7$∆$P = 760 kgf$

USI SAC 50$

METAL DE BASE$ZTA$METAL DE SOLDA$

da

/dN

(m

m/c

iclo

s)$

Delta K (MPa*m^1/2)$

g*9,)&$_>!!$ G$H,)B&$.al.?$versu#$∆v$3&)&$%('&1$ .($C&#(7$ I/-&$ '()%*2&%(-'($ &4('&.&

($I/-&$4,-.*.&`$d$�$O7f`$4$�$NO$qI

1$ 10$ 100$1E-7$

1E-6$

1E-5$

1E-4$

1E-3$

0,01$

∆$P = 760 kgf$

USI SAC 50$

ZTA R=0,3$ZTA R=0,7$MS R=0,3$MS R=0,7$MB R=0,3$MB R=0,7$

da/d

N (

mm

/cic

los)$

Delta K (MPa*m^1/2)$

g*9,)&$_>!a$G$H,)B&$.al.?$versus$∆v$3&)&$%('&1$.($C&#(7$I/-&$'()%*2&%(-'($&4('&.&$(

I/-&$4,-.*.&`$d$�$O7f$($O7N`$$4$�$NO$qI

fT

?/'&G#($ +,($ &1'()&56(#$ -/$ B&1/)$ ./$ 4&'/)$ d$ -0/$ *-41,(-2*&)&%$ #*9-*4*2&'*B&%(-'($ /

3/#*2*/-&%(-'/$ .&#$ 2,)B&#7$ (#'&-./$ 3/*#$ .($ &2/)./$ 2/%$ VdE?H"$ et alli$ P!ST_U$ (

u"LZgd"QL$P!SSYU7$#(-./$+,($&3(-&#$-&$)(9*0/$.($*-A2*/$.($3)/3&9&50/$.($')*-2&#$PQU

3&)&$/$XV$2/%$4&'/)$.($2&)9&$*9,&1$&$O7f$#/4)(,$,%&$3(+,(-&$&1'()&50/7$.*%*-,*-./$/

B&1/)$ 1*%*&)$ Pthreshold, ∆v'8U>$ ?/'&G#(7$ '&%CK%7$ +,($ /$ XV$ &3)(#(-'/,$ 3*/)

.(#(%3(-8/7$ 3/*#$ /#$ B&1/)(#$ 3&)&$∆v'87$ -/#$ ./*#$ -AB(*#$ .($ 2&))(9&%(-'/$ Pd$ �$ O7N$ (

d$�$O7fU7$4/)&%$*-4()*/)(#$(%$)(1&50/$:#$/,')&#$)(9*6(#$Pw^E$($wgU>

6.7 - Análise de fraturas

E$3&)'*)$./#$HJ#$(-#&*&./#$&-&1*#/,G#($&#$%*2)/4)&2'/9)&4*&#$./#$%(#%/#7$,'*1*I&-./G#(

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6.7.1 - Microfractografias de CPs ensaiados em impacto Charpy

E#$ #,3()4A2*(#$ .($ 4)&',)&$ ./$ %&'()*&1$ #/1.&./$ (-#&*&./$ -/#$ (-#&*/#$ .($ *%3&2'/$ #0/

%/#')&.&#$ &')&BK#$ .&#$ g*9,)&#$ _>!NG_>aO>$ ?/'&G#($ /$ (4(*'/$ .&$ %&*/)$ 4)&9*1*I&50/$ ./

%&'()*&1$:$%(.*.&$+,($&$ '(%3()&',)&$K$.*%*-,A.&7$&')&BK#$.($ 4&2('&#$.($ 21*B&9(%>$?/

(-'&-'/7$ 2/%$ /$ &,%(-'/$ .&$ '(%3()&',)&7$ 3/)$ (M(%31/7$ &2*%&$ .($ O/H7$ -/'&G#($ /

#,)9*%(-'/$ '&%CK%$ .($ dimples7$ 2&)&2'()*I&-./$ /$ &#3(2'/$ .h2'*1$ .&$ 4)&',)&$ (%

'(%3()&',)&#$)(1&'*B&%(-'($&1'&#>

g*9,)&$_>!N$G$X*2)/4)&2'/9)&4*&$./$%&'()*&1

-&$ )(9*0/$ .&$ w^E`$ (-'&18($ &/

1/-9/$ ./$ 2/).0/$ .($ #/1.&`

G!Sf/H`$ 4&2('&#$ .($ 21*B&9(%`

&,%(-'/$.($fYOo$PXZpU

g*9,)&$_>!Y$G$X*2)/4)&2'/9)&4*&$./$%&'()*&1

-&$)(9*0/$.&$w^E`$(-'&18($&/

1/-9/$ ./$ 2/).0/$ .($ #/1.&`

O/H`$ 4)&',)&$ #(%*G4)@9*1`

&,%(-'/$.($fYOo$PXZpU

$$g*9,)&$ _>!\$ G$ Q.(%$ :$ g*9,)&$ _>!N`

&,%(-'/$ .($ !YOOo

PXZpU

$$$$$g*9,)&$ _>!_$ G$ Q.(%$ :$ g*9,)&$ _>!Y`

!$ G$dimples`$ a$ G$ 4&2('&#

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1/-9/$ .&$ (#3(##,)&`$ GTY/H`

4)&',)&$ #(%*G4)@9*1`$ &,%(-'/

.($fYOo$PXZpU

$$$$g*9,)&$ _>!T$ G$ Q.(%$ :$ g*9,)&$ _>!f`

&,%(-'/$ .($ !YOOo

PXZpU

$$$$$ $$$$$$$$$$

g*9,)&$ _>!S$ G$X*2)/4)&2'/9)&4*&$ ./$%&'()*&1

-&$ )(9*0/$ .&$ w^E`$ (-'&18($ &/

1/-9/$ .&$ (#3(##,)&`$ GY/H`

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.($fYOo$PXZpU

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&,%(-'/$ .($ !YOOo

PXZpU

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6.7.2 - Microfractografias de CPs ensaiados em tenacidade à fratura

E#$g*9,)&#$_>a!G_>NN$*1,#')&%$/$&#3(2'/$%*2)/4)&2'/9)@4*2/$.($&19,-#$HJ#$)/%3*./#$-/#

(-#&*/#$ .($ '(-&2*.&.($ :$ 4)&',)&>$"C#()B&G#(7$ +,($ &#$ ')=#$ )(9*6(#$ PXV7$ w^E$ ($ wgU$ ./

%&'()*&1$ #/1.&./$ /$ %&'()*&1$ &3)(#(-'/,$ 4)&',)&$ .h2'*17$ 2&)&2'()*I&.&$ 3(1&$ 3)(#(-5&$ .(

dimples>$Q#'/$3/.($#()$/C#()B&./$-/$')&C&18/$.($XEd^Q?R$et alli$PaOO!U>

$$$$$ $$$$$$$$$$$$$

g*9,)&$ _>a!$ G$ X*2)/4)&2'/9)&4*&$ .($ HJ

(%3)(9&./$ -/$ (-#&*/$ .(

'(-&2*.&.(`$ (-'&18($ -&

wg`$ )(9*0/$ .&$ 3)KG')*-2&

.($ 4&.*9&`$ &,%(-'/$ .(

!OOOo$PXZpU

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4)&',)&$ .h2'*1`$ &,%(-'/$ .(

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$$$$$$$

g*9,)&$ _>a\$ G$ X*2)/4)&2'/9)&4*&$ .($ HJ

(-#&*&./$ (%$ '(-&2*.&.($ :

4)&',)&`$ (-'&18($ -&$ w^E`

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PXZpU

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4)&',)&`$ (-'&18($ -&$ w^E`

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4)&',)&`$ &,%(-'/$.($aOOo

PXZpU

g*9,)&$ _>a_$ G$ X*2)/4)&2'/9)&4*&$ .($ HJ$ (-#&*&./$ (%$ '(-&2*.&.($ :$ 4)&',)&`$ (-'&18($ -&

w^E`$)(9*0/$.($4)&',)&`$&,%(-'/$.($!OOo$PXZpU

TN

$$$$ $$$$$$$$

g*9,)&$ _>af$ G$ X*2)/4)&2'/9)&4*&$ .($ HJ

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4)&',)&`$ (-'&18($ -&$ w^E`

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4)&',)&`$ (-'&18($ -/$ XV`

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PXZpU

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4)&',)&`$ (-'&18($ -/$ XV`

)(9*0/$.($')&-#*50/$(-')($&

3)KG')*-2&$ .($ 4&.*9&$ ($ &

4)&',)&`$ &,%(-'/$.($aOOo

PXZpU

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g*9,)&$_>N!$G$X*2)/4)&2'/9)&4*&$.($HJ$(-#&*&./$(%$'(-&2*.&.($:$4)&',)&`$(-'&18($-/$XV`

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g*9,)&$ _>Na$ G$ X*2)/4)&2'/9)&4*&$ .($ HJ

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4)&',)&`$ (-'&18($ -/$ XV`

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3)(#(-5&$ .($ 3&)'A2,1&`

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PXZpU

TY

6.7.3 - Microfractografias de CPs ensaiados à fadiga

E#$ #,3()4A2*(#$ .($ 4)&',)&$ ./$ %&'()*&1$ (-#&*&./$ :$ 4&.*9&$ #0/$ %/#')&.&#$ &')&BK#$ .&#

g*9,)&#$_>N\G_>N_>$"C#()B&G#($+,($-&#$')=#$)(9*6(#$&-&1*#&.&#$8/,B($&$2&)&2'()*I&50/$.(

4)&',)&$ .h2'*17$ 2/-4*)%&-./$ .(#'&$ 4/)%&$ /$ '*3/$ .($ 4)&',)&$ (#3()&.&7$ ,%&$ B(I$ +,($ /#

(-#&*/#$.($4&.*9&$4/)&%$)(&1*I&./#$:$'(%3()&',)&$&%C*(-'($PaY/HU>

$$$ $$$$$$$$$$$

g*9,)&$ _>N\$ G$ X*2)/4)&2'/9)&4*&$ .($ HJ

(-#&*&./$:$ 4&.*9&`$(-'&18(

-/$XV`$ )(9*0/$ .($ 4)&',)&

./$HJ`$ &,%(-'/$ .($ YOOo

PXZpU

$$g*9,)&$ _>NY$ G$ X*2)/4)&2'/9)&4*&$ .($ HJ

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-&$w^E`$)(9*0/$.($$4)&',)&

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PXZpU

g*9,)&$ _>N_$ G$ X*2)/4)&2'/9)&4*&$ .($ HJ$ (-#&*&./$ :

4&.*9&`$(-'&18($-&$wg`$ )(9*0/$.($4)&',)&

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T_

7. CONCLUSÕES

G E$3&)'*)$ .($ (-#&*/#$.($ *%3&2'/$H8&)3r$B()*4*2/,G#($+,($/#$HJ#$ (%$+,($/$ (-'&18(

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.h2'*1l4)@9*1$%(-/)7$3/)'&-'/$%(18/)$.(#(%3(-8/`

G "#$ B&1/)(#$ .($ '(-&2*.&.($ /C'*./#$ -/#$ (-#&*/#$ 4/)&%$ *-4()*/)(#$ &/#$ (-2/-')&./#

&')&BK#$ .($ (+,&50/$ (%3A)*2&$ +,($ 2/))(1&2*/-&$ '(-&2*.&.($ :$ 4)&',)&$ 2/%$ (-()9*&

&C#/)B*.&$-/#$(-#&*/#$.($*%3&2'/$H8&)3r`

G E')&BK#$./#$(-#&*/#$.($'(-&2*.&.($:$4)&',)&$/C'(B(G#($B&1/)(#$.($ve7$/-.($B()*4*2/,G

#($+,($&#$')=#$)(9*6(#$PXV7$w^E$($wgU$&3)(#(-'&)&%$B&1/)(#$3)<M*%/#`

G "$(-#&*/$.($')&50/$%/#')/,$+,($&$4)&',)&$/2/))(,$-/$%('&1$C&#(`$*#'/$#*9-*4*2&$+,($/

3)/2(##/$.($,-*0/$3/)$#/1.&9(%$-(#'($%&'()*&1$4/*$&.(+,&./`

G "#$(-#&*/#$.($4&.*9&$%/#')&)&%$+,($&$%(-/)$)(#*#'=-2*&$&/$*-A2*/$.($3)/3&9&50/$.(

')*-2&$4/*$-/$%('&1$C&#(7$4&'/)$d$�$O7f7$2/%$�v'8$ %XJ&\≅ `$-/$(-'&-'/7$&$%&*/)

)(#*#'=-2*&$4/*$-&$I/-&$4,-.*.&7$2/%$d$�$O7N`

G p()*4*2/,G#($ +,($ /$ 4/)%&'/$ C@#*2/$ .&$ 2,)B&$ .($ 3)/3&9&50/$ .($ ')*-2&$ 3/)$ 4&.*9&

versus$2&))(9&%(-'/$3)&'*2&%(-'($ *-.(3(-.($.&$ )(1&50/$.($ 2&))(9&%(-'/$d7$($+,(

(%$2()'/#$#(9%(-'/#$.&$)(9*0/$QQ$&#$2,)B&#$#($#,3()36(%`

G "$(-#&*/$.($Q-'(9)&1$z$#()B*,$2/%/$'K2-*2&$#,31(%(-'&)$3&)&$&B&1*&50/$.&$'(-&2*.&.(

:$ 4)&',)&$ ./$ %&'()*&17$ /-.($ (-2/-')/,G#($ /$ B&1/)$ .($ zQH$ 3&)&$ /$ %('&1$ C&#($ .(

&3)/M*%&.&%(-'($SS7Y$?%%l%%a`

G E#$&-@1*#(#$.($4)&',)&#$./#$HJ#$(-#&*&./#$%/#')&)&%$+,($3&)&$(-#&*/#$.($ *%3&2'/

H8&)3r$ (%$ iC&*M&#$ '(%3()&',)&#j$ 8@$ '(-.=-2*&$ .($ 4)&9*1*I&50/$ ./$ %&'()*&17$ 2/%

4&2('&#$ .($ 21*B&9(%>$ ?/#$ (-#&*/#$ .($ 4&.*9&7$ /C#()B/,G#($ /#$ &#3(2'/#$ 'A3*2/#$ .(

#,3()4A2*(#$.($4)&',)&$3/)$4&.*9&$($.($),3',)&$3/)$')&50/7$/-.($3F.(G#($/C#()B&)$/#

idimplesj7$2&)&2'()A#'*2/#$.($4)&',)&$.h2'*1>

Tf

8. SUGESTÕES PARA TRABALHOS FUTUROS

G Z%3)(9&)$ /,')/$ '*3/$ .($ 'K2-*2&$ .($ #/1.&9(%7$ 3/)$ (M(%31/7$XQu7$ 3&)&$ &B&1*&)$ &#

2&)&2'()A#'*2&#$2/%3/)'&%(-'&*#$./$%&'()*&1`

G Z%3)(9&)$/$HJ$./$'*3/$2&))(9&%(-'/$(%$')=#$3/-'/#`

G d(&1*I&)$ (-#&*/$ .($ Q-'(9)&1$ z$ &31*2&-./G#($ B@)*/#$ HJ#7$ '*)&-./G#($ ,%&$%K.*&$ ./#

)(#,1'&./#$/C'*./#$($2/%3&)&)$2/%$/$)(#,1'&./$/C'*./$3(1/$(-#&*/$.($,%$h-*2/$HJ`

G Z#',.&)$/$2/%3/)'&%(-'/$.($(#'),',)&#$%('@1*2&#$(%$'&%&-8/$)(&17$#,D(*'&#$:$2&)9&#

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TT

9. REFERÊNCIAS BIBLIOGRÁFICAS

!> EXZdQHE?$ ERR"HQE^Q"?$ "g$ R^E^Z$ qQuqcE�$ E?L$ ^dE?RJ"d^E^Q"?"ggQHQEmR>$ Standard specifications for highway bridges. !a>$ (.>$ c&#8*-9'/-7!Sff>

a> EXZdQHE?$ Q?R^Q^W^Z$ "g$ R^ZZm$ H"?R^dWH^Q"?>$ Specification for thedesign, fabrication and erection of structural buildings.$S>$(.>$H8*2&9/7$!STS>

N> EXZdQHE?$R"HQZ^�$g"d$^ZR^Q?u$E?L$XE^ZdQEmR>$Standard test methodfor plane-strain toughness of metallic materials7$Z$NSSG!SSO

\> EXZdQHE?$R"HQZ^�$g"d$^ZR^Q?u$E?L$XE^ZdQEmR>$Standard test methodfor JIC, a measure of fracture toughness7$Z$T!NG!STS

Y> EXZdQHE?$R"HQZ^�$g"d$XZ^EmR>$ASM Handbook.$$S>$$(.>$$!SSa>$B>$!!>

_> EXZdQHE?$R"HQZ^�$g"d$XZ^EmR>$Metals handbook>$"8*/[$X('&1#$J&)s7$$!Sf!>B>$_>

f> E?LZdR"?7$^>$m. Fracture mechanics – Fundamentals e applications>$V/2&$$$$$$d&'/-$[$HdH$J)(##7$!SS!>

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!O> VZmmZQ7$Q>$q>$Edifícios industriais em aço>$$R0/$J&,1/[$J*-*7$!SS\>

!!> VdE?H"7$ H>$ $ E>$ u>$X>$ ('$ &11*>$Fadiga de estruturas soldadas>$ m*#C/&[$ g,-.&50/H&1/,#'($u,1C(-s*&-7$!ST_>

!a> Vd"Zv7$L>$Elementary engineering fracture mechanics>$>H/))(2'[$X&)'*-,#$?*D8/447$!ST_>

!N> Vd"Zv7$ L>$ The Pratical use of fracture mechanics>$ \>$ (.>$ L/).)(28'7$ q/11&-.[v1,t()$E2&.(%*2$J,C1*#8()#7$!SS\>

!\> H�?LQL"7$m>$H$($u"LZgd"QL7$m>$V>$Notas de aulas da disciplina Tecnologia demateriais metálicos. ",)/$J)('/[$dZLZXE^$PWg"JlHZ^ZHlWZXuU7$aOOO>$$Y!3>

!Y> HZ^mQ?7$J>$d>$et al. Análise de fraturas>$R0/$J&,1/[EVX7$!ST_>

!_> HqQEpZdQ?Q7$p>$Tecnologia mecânica>$a>$(.>$d*/$.($z&-(*)/[$X&2u)&t$q*117$$!SS_>

TS

!f> LZEeWQ?"7$ H>$ ^>$ Z>$ ($ E?LdELZ7$ E>$ q>$ J>$ E$ *-'(9)&1$ z$ |$ ,%&$ &C/).&9(%(M3()*%(-'&1>$ >$ Q->$ RZXQ?{dQ"$ LZ$ XZH�?QHE$ LE$ gdE^WdE7$ !>7$ !SS_7$ ",)/J)('/>$Anais... ",)/$J)('/[$Wg"J7$!SS_>$ 3>$a\!GaY_>

!T> LQER7$m>$E>$X>$Estruturas de aço: 2/-2(*'/#7$'K2-*2&#$($1*-9,&9(%>$a>$(.>$R0/$J&,1/[w*9,)&'(7$!SST>

!S> Z#&C>$Caracterísiticas dos eletrodos Esab[$2&'@1/9/>$H/-'&9(%7$aOO!>

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a!> u"LZgd"QL7$ m>$ V> Fundamentos de mecânica de fratura>$ a>$ (.>$ ",)/$ J)('/$ [Wg"J7$!SSY>

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aN> qELLdQmm7$L>$X>$Welding fume extraction, a guide to equipment selection>$X('&1H/-#'),2'*/-7$B>$!\7$->$\7$!STa>

a\> vmZR?Qm>$X>`$mWvER7$J>$Fatigue of metallic materials>$J)&9&[$Z1#(B*()7$$!SSa>

aY> vWwXE?"pQH7$ V>$ ($cQmmZXR7$?>$Steel design for structural engineers>$ a>$ (.>?(t$z()#(r[$J)*-'*2($q&117$!STN>

a_> mE?HER^Zd7$z>g>$Metallurgy of welding>$Y>$(.>$m(-.()#$[$H8&3%&-$�$q&117$!SS\>

af> XE?WEm$C)&#*1(*)/$3&)&$2@12,1/$.($(#'),',)&#$%('@1*2&#>$V)&#A1*&7$!STS>$B>$!>

aT> XEdeWZR7$J>$p>$Tecnologia de soldagem>$V(1/$q/)*I/-'($[$ZREV7$!SS!>

aS> XEd^Q?R7$u>$ J>$ et al.$ Q-41,=-2*&$ .($ .(4(*'/#$ 31&-&)(#$ .($ #/1.&9(%$ -&$ '(-&2*.&.($ :4)&',)&$.($&5/$(#'),',)&1$&31*2&./$:$2/-#'),50/$2*B*1>$Projeto Fapemig TEC 2503/967EC)*1GaOO!>

NO> $?W?ZR7$Z>$H>`$?E^Em7$�>$L>$Palestra sobre soldagem>$",)/$J)('/$[$Wg"J7$!STY>

N!> "vWXWdE7$ ^>`$ ^E?QuWHqQ7$ H>$ Engenharia de soldagem e aplicações>$ d*/$ .(z&-(*)/$[$m^H$m*B)/#$^K2-*2/#$($H*(-'A4*2/#7$!STa>

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