Study on Welding Crack of 405 Stainless Clad Steel (Report 2)

Effect of Hydrogen in Weld Metal on Cracking

Abstract

Delayed cracking having long incubation period in AISI 405 stainless steel and its clad steel weldment was described in the previous report.
This investigation is carried out on the effect of hydrogen content in weld metal on delayed cracking. Hydrogen content in weld metal is measured newly, and the relationship between hydrogen content and delayed cracking is investigated.
Conclusions are as follows:
(1) Hydrogen content in weld metal is remarkably reduced by preheating, but maximum hardness is not therely reduced.
This means that the effect of preheating for prevention of weld cracking is based on the reduction of hydrogen rather than the reduction of masimum hardness of weld metal.
(2) Hydrogen diffusion coefficient of AISI 405 stainless steel is calculated. This calculated value is 1/10-1/25 of carbon steel at room temperature. This is one of the reasons that delayed cracking having long incubation period is observed with AISI 405 stainless steel weldment, but never with structural steel weld-ment.