Study on the Improvement of Bending Properties of 405 Stainless Steel Weldment (Report 1)

Abstract

Delayed cracking having long incubation period which occurs in 405 stainless steel weldment was described.
Bending test results of the weldment without delayed cracking are much scattered in elongation.
Bending test of weldment was carried out using different chemical composition materials and some post heat treatment, and mechanical properties of bond were studied with thermal recycled specimen.
Following are the reasons for bending results of weldment being scattered and for improvement of bending properties through this investigation.
1. The reason for poor bending result of 405 weldment-is coexistence of martensite and coarsed ferrite grain at welded bond.
2. More Al content of 405 stainless steel induces coarse ferrite grain at welded bond, which means that in the case of 0.05%, Q, Al less than 0.11% is desirable, and in the case of 0.18% Al, C about 0.08%, is desirable.
3. Martensite in welded bond is decomposed by low temperature heat treatment such as 250C×lhr, 350C×1hr.
This is the reason that bending results of weldment are improved by this heat treatment.