锆合金压力电阻焊接头热影响区中第二相的组织特征

Microstructure Characteristics of the Second Phase in Heat Affected Zone of Pressure Resistance Welded Joints of Zircaloys

采用热模拟试验机分别对Zr-4合金管和锆锡铌(Zr-Sn-Nb)系锆合金管与Zr-4合金柱进行压力电阻焊连接,研究了接头热影响区的第二相形貌、成分和晶体结构,并与母材进行对比。结果表明:在压力电阻焊的热力耦合作用下,Zr-4合金接头热影响区近熔合线区的第二相粒子发生完全溶解,近母材区的密排六方结构Zr(Fe,Cr)2Laves第二相颗粒的数量相比母材显著减少,平均直径增大。Zr-Sn-Nb系合金接头热影响区近熔合线区的第二相颗粒数量很少,以直径小于50nm的体心立方结构β-Nb相为主,近母材区的第二相颗粒数量介于母材与热影响区近熔合线区之间,由细小的体心立方结构β-Nb相以及粗大的面心立方结构(Zr,Nb)Fe2相组成。

The Zr-4 alloy tube and Zr-Sn-Nb zircaloy tube were connected with Zr-4 alloy column by pressure resistance welding on a thermal simulator.The morphology,composition and crystal structure of the second phase in the heat affected zone of the joint were studied and compared with those of the base metal.The results show that the second phase particles in the heat affected zone near the fusion line of Zr-4 alloy joint were completely dissolved under the thermo-mechanical coupling effect of pressure resistance welding,and the number of the second phase particles of the hexagonal close-packed structure Zr(Fe,Cr)2 Laves phase near the base metal was significantly reduced,and the average diameter increased.The number of the second phase particles in the heat affected zone near the fusion line of the Zr-Sn-Nb alloy joint was small,and mainly consisted of body-centered cubic structureβ-Nb phase with a diameter less than 50 nm.The number of the second phase particles in the heat affected zone near the base metal was between that of the base metal and that in the heat affect zone near fusion line,and the second phase was composed of fine body-centered cubic structureβ-Nb phase and coarse face-centered cubic structure(Zr,Nb)Fe2 phase.