of cracked part for welded joint of 12Cr2MoWVBiT(G102) steel tube on hightemperature superheater has been carried out. Results shows that the quench hardening martensitic organism exists in heat effect zone of the welded joint
HV value reaching 391~450
being higher than hardness of G102 steel's basic structure
the hydogen concentration after welding exceeding standard
being easily to produce cold cracks
thereby cracking failure of the welded joint occurred.