焊后热处理对奥氏体／珠光体钢接头熔合区断裂形态的影响

Effect of Post-Weld Heat Treatment on Fractographies of the Transition Zone in Dissimilar A/P Welded Joints

利用扫描电镜对比观察了不同碳含量母材的奥氏体（Ａ）／珠光体（Ｐ）异种钢焊接接头熔合区在焊态和焊后热处理后的断口形态与对应的金相组织。发现焊态接头熔合区的断裂形态由滑移变形、浅纫窝和准解理小面组成，而焊后热处理接头熔合区的断裂形态为碳化物带＋放射状解理混合花样．在熔合区两侧可看到明显的边界线和脆－韧转变特征。初步讨论了熔合区断口的形成机理和焊后热处理对它的影响。

The metallography and fractography of the transition zone in as-welded and post-weld heat treated (PWHT) dissimilar austenite-pearlite(A/p) welded joints have been examined comparatively by using scanning electron microscope(SEM).It is found that there are different microstructures in transition zone corresponding to different joints. In the as-welded joint, the fractography of the transition zone consists of slip deformation lines, quasicleavage facets and dimples. However, in the PWHT joint, the transition zone is transformed into a carbide particles zone and a radial zone.There are two interfaces on both sides of the transition zone and the ductile-brittle transformation characterization is obvious in both joints. The formation mechanism and the effect of PWHT on the fractography of the transition zone are discussed preliminarily.