| Microhardness change and phase transformation behaviors were investigated in the cold rolled C300 and T300 maraging steels after electron beam welding and heat treatments. Although the hardness variations around weldments were similar in both steels, the hardness well of aged specimen of T300 maraging steel was wider and deeper than that of the C300 steel. The as-welded and solution treated and aged C300 maraging steel had fully martensitic structure, but welded and aged one had austenitic phase. On the other hand, the T300 maraging steel always had austenitic phase in martensitic matrix structure. The phase instability on welded zone in T300 maraging steel was severer than that in C300 maraging steel mainly due to no Co element and severer segregation of Ni, Mo, Ti elements, which resulted in wider and deeper hardness well. |
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