CI Example

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METALLURGICAL LABORATORY

Example of Conformance Inspection 1

METALLURGICAL INSPECTION

Metallurgical inspection of the component(s) consists of one or more of the following, as required by

the TDP, STDP, engineering drawings, relevant engineering specifications, and AMCOM direction.The results of the metallurgical inspection are shown in Table 7. x, where x denotes a particular

component (e.g. the table for the first component is denoted Table 7.1 and the table for the secondcomponent is denoted Table 7.2). The data sheets and photographs are included in the applicablecomponent enclosure.

Shot Peening – Shot peening evaluation is performed by qualitatively evaluating shot peeningcharacteristics such as dimple size, degree of coverage, dimple overlap, overspray, and masking. As

required, either the entire component surface or selected regions are inspected. A low-powerstereomicroscope (up to 50X magnification) is used for the evaluation and the typical appearance isrecorded via a high-resolution digital imaging system.

Electrical Conductivity – Electrical conductivity is inductively measured using the eddy currenttechnique to verify the heat treatment (temper) of aluminum and magnesium alloys.

Nital Etch – Nital etch inspection is typically performed by chemically etching the component baresurface with a solution of nitric acid (2 to 4%) in alcohol (ethanol or methanol). The etched surfaceis examined visually to detect detrimental microstructural modifications (e.g. untempered

martensite) that result from overheating during improper machining (e.g. surface grinding). Othersolutions may be used depending on requirements. The inspection is also known as “Temper Etch”.

Bulk (Average) Hardness – Hardness is measured by using standard or superficial hardness testers atthe locations specified by the TDP. Where measurement locations are not specified by the TDP, theDTB Engineering Department will identify appropriate locations for the tests. For case hardened

components, the hardness is measured separately for the case and the core. For very smallcomponents, the hardness is measured on a metallographic section by using a microhardness tester.

Bulk (Average) Composition – Composition is measured by using an arc emission spectrometer orInductively Coupled Plasma – Atomic Emission Spectrometer (ICP-AES). Where required, EnergyDispersive Spectroscopy (EDS) is used to supplement the results.

Microstructure – Microstructure is evaluated by using standard metallographic techniques includingsectioning, mounting, polishing, chemical etching, and inverted optical microscopy in bright field or

polarized light as necessary. When required, the analysis is supplemented by scanning electronmicroscopy. Additional metallurgical inspections are performed only when required by the TDP. Itshould be noted that the particular technique(s) used for the microstructural analysis of a component

may vary with respect to the type and sequence used.

Heat Treatment – Heat treatment is checked by coupled microstructural evaluation and hardness

measurements, and supplemented by electrical conductivity measurements when necessary.

Inclusions – Inclusions are checked by using appropriate metallographic sections to analyzeinclusion type and amount (volume fraction or length). When required, composition of the inclusions

is checked by EDS.

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Plating/Coating – Composition and thickness are checked using an appropriate metallographic

section that includes a representative plated or coated surface. Plating or coating thickness ismeasured on the metallographically prepared section using a calibrated digital measurement system.Composition is analyzed by a combination of scanning electron microscopy and energy dispersive

spectroscopy.

Grain Size – Grain structure is revealed by appropriate chemical etchants and measured bycomparison using a microscope eyepiece equipped with the standard ASTM grain size grid. When

necessary (e.g. for very fine or coarse grain sizes outside the range of the grid), standardstereological measurements are performed.

Grain Flow – Grain flow is determined by using a section(s) of appropriate size and orientation. Thesection is prepared using standard metallographic techniques, and chemically etched to reveal the

grain structure and deformation patterns. The grain flow is analyzed with respect to the componentgeometry and photographically recorded using either an inverted optical metallograph or macrolevelhigh-resolution digital imaging.

Decarburization – Decarburization is checked by using appropriate metallographic sections thatinclude a representative portion of the component surface. Chemical etching is used to reveal thepresence of decarburization. If decarburization is detected, the depth is measured using a calibrated

digital image analysis system and compared with the requirements. In addition, if the decarburizedlayer is of sufficient depth, microhardness measurements are used as a confirmatory test.

Retained Austenite – Retained austenite is revealed by special chemical etching of standardmetallographic sections. Microstructural estimation of retained austenite content is performed by

standard stereological volume fraction counts. If the retained austenite content is found to exceed 3%by volume, X-ray diffraction is used as a confirmatory test and the results provided for comparison.

Case Hardening – Case hardening is checked by using an appropriate metallographic section that

includes a representative portion of the component surface. The “case” is revealed by an appropriatechemical etchant and measured by a microhardness scan from the surface to the interior. Typically,the case depth is reported as the distance from the surface at which the hardness is HRC 50.

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Table 7.1 – Results of Metallurgical Analysis of Rod End Assembly (Rod End),Part No. 114CS123-1

Inspection Specification Requirement Actual Reading Findings

Photo

No.

CC

(4)

Shot Peening Drawing No.

114CS123,

Notes 3, 4,

13 and 18,

MS21.01*

200% Coverage

on Rod End

bore

Satisfactory, Rod End

bore shot peened with

uniform intensity and

coverage > 100%. Cd

peaks were detected by

EDS inside the bore,

with a plating thicknessof .00030.

N/A* 2.1 4

Bulk Hardness Drawing No.

114CS123,

Notes 11 and

19

HRC 39 – 42 HRC 42.0, 42.0, 42.0 Meets requirements. No

anomalies were noted.

--- 4

Average

Composition

AMS-S-5000 4340 Steel 4340 Steel. See analysis

report.

Meets requirements. No


---

Grain Flow Drawing No.

114CS123,

Note 13 and

ADCN No. 9

Rolled Threads Satisfactory for Rolled

Threads. See

representative

photograph.



2.2

Microstructure AMS-S-5000 4340 Steel Nominal for 4340 Steel,

microstructure showsuniformly tempered

martensite.

Nominally meets

requirements. Noanomalies were noted.

2.3

Heat Treatment Drawing No.

114CS123,

Note 11

HRC 39 – 42 Satisfactory based on

hardness and

microstructure.



---

Grain Size AMS-S-5000 ASTM No. 5 or

finer with

occasional

grains as large

as ASTM No. 3

Finer than ASTM No. 5. Meets requirements. No


---

Decarburization AMS-S-5000 Section

3.6

Satisfactory. No

decarburization was

detected.



---

Cadmium

Plating

(Composition)

A qualitative EDS was

performed. Cd was

detected both on theRod End surface and

bore.

Nominally meets

requirements. No


--- **Plating/Coating AMS-QQ-P-

416

Check andReport,

typically .0003

- .0008

(Thickness)

The Cadmium Platingmeasured .00048 on the

Rod End surface and

.00030 on the Rod End

bore.

No anomalies werenoted.

2.42.5

*Specification was not available.**Baking after cadmium plating is a <<CC>>; it cannot be verified.

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Table 7.2 – Results of Metallurgical Analysis of Rod End Assembly (Bearing),

Part No. 114CS123-1

Inspection Specification Requirement Actual Reading Findings

Photo

No.

CC

(4)

Bulk Hardness None

Listed

Check and

report

Ball: HRC 58.0, 58.0,

58.0

Race: HR15N 79.0,

80.0, 80.0 ≅ HRC 38.5

N/A ---

Average

Composition

None

Listed

Check and

report

Ball: 17-4 PH CRES

per AMS-QQ-S-763

Race: 17-4 PH CRES

per AMS 5643

N/A ---

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8/6/2019 CI Example




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