Fabrication of 321 321H 1.4541 1.4878 Stainless Steel

Austenitic stainless steel pipe are considered to be the most weldable of the high-alloy steel and can be welded by all fusion and resistance welding processes. Two important considerations in producing weld joints in the austenitic stainless steel tubing are preservation of corrosion resistance and avoidance of cracking.

It is important to maintain the level of stabilizing element present in Alloys 321 and 347 during welding. Alloy 321 is more prone to loss of titanium. Alloy 347 is more resistant to loss of columbium. Care needs to be exercised to avoid pickup of carbon from oils and other sources and nitrogen from air. Weld practices which include attention to cleanliness and good inert gas shielding are recommended for these stabilized grades as well as other non-stabilized austenitic alloys.

Weld metal with a fully austenitic structure is more susceptible to cracking during the welding operation. For this reason, Alloys 321 and 347 are designed to resolidify with a small amount of ferrite to minimize cracking susceptibility. Columbium stabilized stainless steel tube are more prone to hot cracking than titanium stabilized stainless steel.

Matching filler metals are available for welding Alloys 321 and 347 stabilized stainless steel. The Alloy 347 filler metal is sometimes used to weld the 321 alloy. These stabilized alloys may be joined to other stainless steel or carbon steel. Alloy 309 (23% Cr-13.5% Ni) or nickel-base filler metals have been used for this purpose.

SA 213 TP 321 321H