PowerPoint 14 - Welding (MET14300)

What is welding?

Permanently joining materials by heating (and sometimes pressure).

Two main forms of welding?

Solid-state welding and fusion welding.

Solid-state welding?

Joining materials using heat + pressure without melting.

Fusion welding?

Joining materials by melting the base metal.

Five basic joint types?

Butt, lap, tee, corner, edge.

Bead weld?

Simple weld with no edge preparation; used for thin metal.

Groove weld?

Weld requiring edge prep (V, U, J) for thicker metal.

Fillet weld?

Weld used on lap, tee, and corner joints.

Common weld defects?

Cracks, cavities, inclusions, incomplete fusion, spatter, distortion.

HAZ (Heat Affected Zone)?

Region around weld where properties change due to heat.

Residual stresses in welding?

Caused by uneven heating/cooling → distortion or cracking.

Weldability?

How well a material can be welded based on properties and process.

Arc welding?

Using electrical arc to melt metal.

Consumable electrode process?

Electrode melts and becomes filler metal.

Non-consumable electrode process?

Tungsten electrode does not melt (TIG/GTAW).

SMAW (Stick welding)?

Uses coated stick electrode; cheap; requires slag removal.

GMAW (MIG welding)?

Uses continuous wire; cleaner and faster than SMAW.

GTAW (TIG welding)?

High-quality welds using tungsten electrode and inert gas.

PAW (Plasma arc welding)?

Very hot concentrated arc producing narrow, deep welds