Effect of delta ferrite on the mechanical properties of dissimilar ferritic-austenitic stainless steel welds

Abstract

The dissimilar welds of AISI 304 to AISI 430 stainless steel was investigated by using gas tungsten arc welding. Three filler metals including ER309L, ER316L and ER2594 were applied. The weakest region of the welds was the heat affected zone of 430 stainless steel due to the formation of martensite. Also, the wide grain growth zone was observed in this side. The ferrite number for type 309L, 316L and 2594 weld metals was about 15, 32 and 57, respectively. The hardness and tensile strength values of the weld metals were higher than that of the heat affected zones and the base metals. The ferrite presented higher hardness values than the austenite in type 316L and 309L joints; while the hardness of austenite and ferrite was comparable in type 2594 weld metal.