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以热机械处理获得的超细晶1.6%C超高碳钢为研究对象,借助电致超塑性压缩试验研究了电场强度和初始应变速率对超高碳钢超塑性的影响,并探讨了其与40Cr钢电致超塑性焊接的可行性。实验结果表明,在压缩温度780℃、初始应变速率(0.5—5.0)×10-4s-1,试样接正极环状电极接负极条件下,超高碳钢的应力应变曲线呈现出明显的超塑性压缩流变特征,其应变速率敏感性指数为0.46;当电场强度为3kV/cm时,其超塑稳态流变应力降低10%以上。在焊接温度780℃、初始应变速率1.5×10-4s-1、预压应力56.6MPa、电场强度3kV/cm条件下,超高碳钢与40Cr钢实现了电致超塑性焊接,其接头拉伸强度达到533MPa,比不加电场时增加15%。
The effects of electric field strength and initial strain rate on the superplasticity of ultra-high carbon steel were investigated by means of the induced superplastic compression test with the ultra-fine 1.6% C ultra-high carbon steel obtained by thermo-mechanical treatment as the research object. Feasibility of Superplastic Welding of 40Cr Steel. The experimental results show that the stress-strain curve of ultra-high carbon steel shows a significant super-strain at a compression temperature of 780 ℃, an initial strain rate (0.5-5.0) × 10-4s-1, Plastic compressive rheological characteristics, the strain rate sensitivity index is 0.46; when the electric field intensity is 3kV / cm, the superplastic steady-state flow stress decreases by more than 10%. The superplastic welding of ultra-high carbon steel and 40Cr steel was achieved at a welding temperature of 780 ℃, an initial strain rate of 1.5 × 10-4s-1, a pre-stress of 56.6MPa and an electric field of 3kV / cm. The strength reached 533MPa, an increase of 15% compared with no electric field.