T92/HR3C异种钢焊接接头高温拉伸变形及断裂行为

采用500℃和625℃拉伸试验,研究T92/HR3C异种钢管接头的高温变形及其断裂行为。结果表明,在高温拉伸过程中,焊缝、T92侧热影响区(HAZ)及母材(不包含颈缩段)均未发生明显的塑性变形及组织结构的变化,而HR3C侧母材晶粒明显被拉长,HR3C侧HAZ的拉伸变形不明显。HR3C母材塑性变形量随温度升高而明显降低,孪晶回复越少。高温拉伸断口位于T92侧HAZ的细晶区(FGHAZ),呈正断加剪切断的混合断裂方式,均与室温状态下该焊接接头的拉伸变形及断裂行为不同。应力三轴度理论可很好地解释该接头高温短时拉伸变形及断裂特征。

Tensile plastic deformation and fracture behavior of T92/HR3C dissimilar welded joints at high temperatures

Short-term tensile tests of T92/HR3C dissimilar weldedJoints were carried out at 500 ℃ and 625 ℃ to study plastic deformation and fracture behavior of the joints at high temperature.The results show that there are no observable plastic deformation and structural evolution at the welding seam,the heat affected zone(HAZ) of T92,T92 base metal and the HAZ of HR3C steel during the high-temperature tensile tests,except the necking section of the specimens.However,grains of the HR3C base metal are obviously elongated.Plastic deformation of the HR3C base metal decreases with increasing the testing temperature with less twin recovery.The high-temperature tensile fracture of the joints is located at the fine-grained heat affected zone(FGHAZ) closed to the T92 base metal,and a mixed fracture mode under normal stress and shear stress was present,which is different from those of the joints during room temperature tensile tests.The stress triaxiality theory was successfully applied to explain the plastic deformation and facture behavior of the joints during the short-term tensile tests at high temperature.