Abstract:
Ferritic stainless steel is typically used in the automotive industry to fabricate welded tube that is plastically
deformed for flanging, bending and necking. The effect of welding parameters during autogenous gastungsten
arc welding (GTAW) of thin sheet on the weld metal structure and tensile properties were
determined. Two grades of ferritic stainless steels, a titanium-containing Grade 441 and a titanium-free
molybdenum-containing Grade 436, were used as base metal. Statistical analysis was used to determine the
influence of welding parameters on the microstructure of autogenous GTAW welds. The results of Grade 441
indicated that the welding speed and peak welding current had a statistically significant influence on the
amount of equiaxed grains that formed. For Grade 436, the same welding parameters (welding speed and
peak welding current) had a statistically significant influence on the grain size of the weld metal grains. The
ductility of a tensile test coupon machined parallel to the weld direction, for both base metal grades, was
unaffected by the welding parameters or the weld metal microstructure. The elongation was determined by
the amount of weld metal in the gauge area of a tensile coupon. The titanium content of the base material
seems to have the most significant effect on the formation of equiaxed grains.
