超高碳钢与表面改性后40Cr的超塑连接

Superplastic Solid State Welding of Ultrahigh Carbon Steel and 40Cr Steel After Surface Modification

研究了1.4%C超高碳钢的压缩超塑性及其与40Cr钢之间的超塑性焊接,分析了接头组织与性能,讨论了焊接机理。结果表明,1.4%C超高碳钢在800℃、初始应变速率(0.75～3.75)×10-4s-1条件下压缩呈现超塑性,应变速率敏感性指数0.31;40Cr钢组织越细,接头强度越高;经表面激光淬火的40Cr与1.4%C超高碳钢在800℃、预压应力56.6MPa、初始应变速率2.5×10-4s-1的条件下压接3.5min,接头强度最高达460MPa,为40Cr钢母材强度的85%,接头胀大率小于4.5%,可实现较精密固态焊接。

The compression superplasticity of 1.4%C ultrahigh carbon steel(UHCS)was investigated,and the superplastic solid state welding of UHCS and 40Cr was conducted.The results show that the UHCS-1.4%C exhibits superplasticity compressed at 800℃ and at initial strain rate of(0.75~3.75)×10-4s-1,and the strain rate sensitivity is 0.31.The finer the martensite grain of 40Cr,the higer strength of the joint.With 40Cr sample's surface being laser hardened,the solid state welding of UHCS/40Cr can be achieved in about 3.5 min under the condition of 800℃,pre-compressed stress of 56.6 MPa,and initial strain rate of 2.5×10-4s-1.The joint strength is up to 460 MPa,which reaches 85% of 40Cr steel strength.The expansion rate of the joint is less than 4.5%,which indicates a precision welding.