摘要:
对聚变堆用CLAM钢进行了激光焊接试验,并对接头进行740℃/1 h焊后回火处理,分别对热处理前、后接头的显微组织及性能进行了研究.结果表明,获得了成形良好、无缺陷的焊接接头;焊态下,焊缝由淬硬的板条马氏体和大量的δ铁素体组织组成.完全淬火区由板条马氏体和极少量的δ铁素体组成,其硬度高达545 HV;焊后热处理使焊缝及完全淬火区的板条马氏体分别转变为碳化物弥散分布的回火马氏体和回火索氏体组织.显著降低了接头的淬硬程度,最大硬度仅比母材高约15%;焊后回火热处理前、后接头的抗拉强度均高于基体母材,虽然焊后热处理使接头强度有所降低,但仍达到原始母材的98%以上.
Abstract:
China low activation martensitic steel used for fusion reactor was welded by laser welding process,and followed by the post-welding heat treatment(PWHT) at 740℃ for 1 h.The characteristics of microstructure and mechanical properties of welded joints were analyzed before and after PWHT,respectively.The results show that the weld seam with good formation and without defects has been obtained.In as-welded condition,the microstructure obtained in weld metal is quench hardening lath martensite with high percentage of delta ferrite.The hardness value of full quenched zone is up to 545 HV due to its fine lath martensie besides of small percentage of delta ferrite.After the PWHT,the lath martensite,in the weld metal and the completely quenching zone,transformed into tempered martensite and tempered sorbite with dispersed carbides,which decreased the hardenability of the weld joint obviously,and the highest microhardness was only 15% higher than that of the base material.The tensile strength of weld joint was higher than the base material both before and after the PWHT.Although the PWHT could decrease the strength of the weld joint,it was also about 98% of the original base material.
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