T91/TP347H异种钢焊接接头服役微观组织转变

异种钢焊接接头在超超临界电站锅炉结构中应用广泛。采用XRD,SEM及EDS及显微硬度对原始态和服役1×10⁵h的T91/TP347H异种钢焊接接头的相组成、显微组织形貌和元素组成进行了表征分析,并采用显微硬度计对2种接头的显微硬度进行了测试。结果表明,相较于原始态,服役1×10⁵h的接头TP347H母材晶粒更为粗大,T91和TP347H的热影响区强化相粗化,焊缝有M₂₃C₆和Nb(C,N)析出。2种状态的焊接接头硬度最高值均出现在T91侧热影响区,最低值均在TP347H母材,服役1×10⁵h的焊接接头焊缝的硬度较原始态有显著提高。

Microstructure transformation of T91/TP347H dissimilar steel welded joint after service

The welded joints of dissimilar steels are widely used in ultra-supercritical power station boiler structure.The microstructure,elements and phase composition of T91/TP347H dissimilar welded joints in original state and service for 1×10⁵h were analyzed by OM,SEM,EDS and XRD,and the microhardness of these two welded joints was tested by microhardness tester.The results showed that,compared with the original state,grains of TP347H base metal after 1×10⁵h service were larger,the strengthening phases of T91 and TP347H in heat affected zone got coarsened,and M₂₃C₆and Nb(C,N)precipitated in the weld.The maximum hardness of both welded joints appeared in the heat affected zone of T91,and the minimum hardness of both welded joints appeared in the base metal of TP347H.Compared with the original state,the hardness of welded joints after 1×10⁵h service increased significantly.