高碳含铜TWIP钢TIG焊接头组织与性能

通过单向拉伸试验、显微组织观察、X射线衍射(XRD)和硬度测试对比研究了Fe-20Mn-3Cu-1.38C TWIP钢钨极氩弧焊(TIG)焊接接头固溶处理前后的组织和力学性能. 结果表明,固溶处理前焊缝组织为特定取向的柱状晶,整个焊缝组织晶粒粗大且分布着密集的颗粒状碳化物,热影响区(HAZ)在晶界有大量碳化物析出;固溶处理后,焊缝组织变为等轴晶,碳化物被完全固溶,焊接接头抗拉强度由953 MPa降为870 MPa,断后伸长率由41.85%提高至66.35%,低于母材性能(抗拉强度1 100 MPa,断后伸长率92.25%),但相比固溶处理前,综合力学性能显著提高;两种拉伸试样均断在热影响区,为典型韧性断裂.

Microstructure and mechanical properties of high-carbon bearing copper TWIP steels TIG welding joint

Microstructure and properties of the Fe-20Mn-3Cu-1.38C TWIP (twinning induced plasticity) steel TIG welding joint before and after solution treatment have been studied by uniaxial tensile test, microstructure observation, X-ray diffraction and microhardness test. The results revealed that the microstructure of welding joint without solution treatment was composed by coarse columnar crystals with specific orientation. Furthermore, a large number of granular carbides precipitated in weld zone and heat affected zone. After solution treatment, the isometric crystal was obtained and the precipitated carbide was dissolved completely. Meanwhile, the tensile strength of welding joint reduced from 953MPa to 870MPa, while the elongation increased from 41.85% to 66.35%. The microstructure and properties has been improved obviously after solution treatment. The tensile strength and elongation of base material is 1 100 MPa and 92.25% respectively. Both kinds of tensile samples fractured in the heat affected zone and the fracture appearance showed typical ductile fracture characteristic.