RESULTS: CMT arc Welding

V- =Dynamic correction: Negative valueVo =Dynamic correction: 0Voff =Dynamic correction offV+ =Dynamic correction: Positive value

Curr

ent

Time

Drop

Arc booster

Voff

Vo

V-

V+

•For Different value of Dynamic Correction, Total Heat Input remains constant.

•For negative values of Dynamic correction factor, Peak temperature increases.•Enabling Dynamic correction factor causes slight increase in voltage hence peak temperature.

Area Voff=Area V0=Area V+= Area V-

Dynamic Correction Factor:

3

Zn coating

High fluidity molten pool

Zn coating

Zn Coating

Zn Coating

Zn vapor to escape

Zn Pore

High speed interrupted

droplet transfer

Welding Wire

Zn coating

Low fluidity molten pool

Zn coating

Zn Coating

Zn CoatingZn Pore

Continu-ous

droplet transfer

Welding Wire

Dynamic Correction Factor: Effect on Welding pool and Droplet transfer

Weld pool behavior and Droplet transfer with neg-ative value of

Dynamic Correction Factor

Weld pool behavior and Droplet transfer with posi-tive value of

Dynamic Correction Factor

Effects of Negative value of Dynamic Correction Factor: •Due to High peak temperature weld pool fluidity increases.• High speed droplet causes swirling in the weld pool. Which pushes out some trapped Zinc vapor, hence porosity de-creases.• As high speed droplets hitting liquid weld pool, chance of spatter increases.

Effects of Positive value of Dynamic Correction Factor: • Though heat input remains constant, peak temperature de-creases and the fluidity of weld pool decreases.•Droplet transfer is continuous. •Due to continuous droplet transfer and low fluidity of weld pool chances of spatter decreases and fine bead shape is at-tainable. However, more porosity can occur.

No Arc Length CorrectionPositive value ofArc Length Correction

Negative value ofArc Length Correction

Arc Length Correction Factor:

With positive value of arc length correction metal droplet transfer occurs from higher position, which causes spatter and higher arc voltage makes wider bead.With negative value, as droplet transfer occurs from shorter distance, spatter is re-duced. And due to low arc voltage narrower bead is obtained.