形变热处理对Cu-Ni-Cr合金组织与性能的影响

采用中频熔炼-铁模铸造-热轧-固溶-冷轧-时效处理工艺,制备了Cu-1.5Ni-0.5Cr合金板材。通过拉伸力学性能测试、电导率测试、金相和透射电子显微镜观察, 研究了不同形变时效条件对该合金组织和性能的影响。结果表明: 合金的高强度主要来源于预冷变形和时效过程中引起的亚结构强化和从过饱和固溶体中析出Cr粒子引起7的析出强化。时效前预冷变形量越大, 合金的强度提高越多, 而电导率只是稍有下降。该合金较好的形变热处理工艺为时效前进行50%的冷变形, 然后在450 ℃条件下保温4 h, 在此工艺条件下, 该合金的抗拉强度、屈服强度、延伸率、电导率分别为: σ_b=415.2 MPa、σ_0.2=368 MPa、δ₅=13.2%、σ_r =41.2%IACS。

Influence of Thermomechanical Treatment on Microstructure and Mechanical Properties of Cu-Ni-Cr Alloy

Cu-Ni-Cr alloy board was made by medium frequency smelting-iron mould casting-hot rolling-solution-cold rolling-aging process. The effect of different deformation aging conditions on the property and microstructure of the alloy was investigated by conductance measurement, mechanical property test, OM and TEM analysis. The results showed that the high strength of the alloy mainly came from the pre-cold deformation, the substructure strengthening resulted from aging and the precipitatation strengthening of Cr particles precipitated from oversaturated solid solution. The larger the pre-cold deformation before aging, the greater the increase of the alloy strength. However, the conductivity decreased only a little. The better thermo-mechanical treatment conditions for the alloy are as the following: cold deformation of 50% before aging, and keeping the temperature of 450℃ for 4 hours. On this condition, the tensile strength, yield strength, elongation rate, conductivity of the alloy were 415 MPa, 368 MPa, 13.2%, 41.2% IACS respectively.