Summary
This paper describes the study of weldability of SKD 61 hot work tool steel by GMAW. The
following conclusions are summarized from the investigation:
1. Microstructures of the welded metal of all conditions after welding and post-weld heat
treatment(PWHT) were composed mainly of martensite with some retained austenite in a
dendritic segregation pattern.
2. The effect of welding on hardness properties, found the higher heat input resulted in increasing
in hardness, which resulted from transformation of retained austenite to martensite.
3. The samples welded with current of 230A showed a secondary hardening effect accompanied
with the transformation of retained austenite to martensite which resulted in an increasing in
hardness when compare to the sample welded with current of 150A. Welding with higher heat
input resulted in larger carbides precipitation, and increasing in martensile phase.