应变速率对低合金高强钢力学性能的影响

摘要

针对HC340LA、HC420LA两种低合金高强钢,研究了准静态和高速拉伸时不同应变速率对其拉伸行为的影响.研究发现,低合金高强钢HC340LA在应变速率ε=5 s-1时,延伸率和抗拉强度分别比准静态下的相应数据增加67%和27.9%；而在应变速率ε=200 s-1时,延伸率和抗拉分别比准静态下的相应数据增加16.7%和25%.低合金高强钢HC420LA在应变速率ε=5 s-1时,延伸率和抗拉强度分别比准静态下的相应数据增加38.5%和16%；在应变速率ε=200 s-1时,延伸率和抗拉强度分别比准静态下的相应数据增加6.4%和18.34%.也就是说,与准静态拉伸相比,高速拉伸状态下的两种低合金高强钢材料具有更好的塑性、更高的抗拉强度和较高的屈强比,同时材料的塑性和抗拉强度随着应变速率的增加呈下降趋势,200 s-1以上的应变速率对低合金高强钢材料塑性的提高并没有多大贡献.%The effect of strain rate on tensile behaviors of two high strength low alloys HC340LA and HC420LA during quasi-static and dynamic tension is studied. The research shows that the elongation increases by 67%and the tensile strength increases by 27.9%when the strain rate rises from 1×10-3 to 5 s-1, and the elongation increases by 16.7%and the tensile strength increases by 25%when the strain rate rises from 1×10-3 to 200 s-1 of the high strength low alloy HC340LA. And the elongation increases by 38.5%and the tensile strength increases by 16%when the strain rate rises from 1×10-3 to 5 s-1, and the elongation increases by 6.4%and the tensile strength increases by 18.34%when the strain rate rises from 1×10-3 to 200 s-1 of the high strength low alloy HC420LA. Better plasticity, higher tensile strength and yield ratio can be found in high speed tensile state than in quasi-static tension. The plasticity and tensile strength decrease with the increasing of the strain rate. The higher strain rate with over strain rate 200 s-1 has less contribution to the improvement of plasticity of the high strength low alloy steel.