设计制作了60个LY160钢材试件,并开展高温冷却后的单轴拉伸试验研究.首先,通过升温、冷却和拉伸试验,得到了LY160钢材在经历20~1 000℃高温冷却后的力学性能;然后,对比了Q235、Q345、Q460和Q690钢材高温加热和浸水冷却后的力学性能;最后,基于试验结果拟合了LY160钢材高温加热和冷却后各力学参数随温度变化的公式.研究结果表明:随着温度的升高,试件的颜色变暗且光泽逐渐消失;应力-应变曲线的屈服平台也随温度的升高而逐渐消失,浸水冷却会导致LY160钢材屈服平台提前消失;温度和冷却方式对LY160钢材的屈服强度和伸长率影响较大,对极限强度和弹性模量的影响较小;300℃以下,力学性能均与室温相近;300℃以上,屈服强度和极限强度变化趋势一致,但屈服强度变化幅度更大;伸长率从700℃开始才有显著变化;弹性模量变化不明显.不同等级的钢材高温冷却后力学性能差别明显,LY160钢材在较低温度(400℃)时,屈服强度已发生显著变化.试验结果与拟合曲线吻合良好,可快速获得LY160钢材高温后力学性能.
Sixty LY160 steel specimens are designed and fabricated and subjected to uniaxial tensile tests after cooling from high temperature. First, the mechanical properties of LY160 steel subjected to temperatures ranging from 20 to 1 000 ℃ are obtained through heating, cooling, and tensile tests. Then, the mechanical properties of Q235, Q345, Q460, and Q690 steels after high-temperature heating and water cooling are compared. Finally, based on the experimental results, formulas describing the temperature-dependent mechanical parameters of LY160 steel after high-temperature heating and cooling are fitted. The results show that as the temperature increases, the color of the specimens darkens, and the luster gradually disappears. In addition, the yield plateau in the stress-strain curve gradually disappears with increasing temperature, while water cooling causes its premature disappearance in LY160 steel. Temperature and cooling methods have a significant impact on the yield strength and elongation of LY160 steel, while their influence on ultimate strength and elastic modulus is relatively small. Below 300 ℃, the mechanical properties remain similar to those at room temperature. Above 300 ℃, the trends in yield strength and ultimate strength are consistent, but the change in yield strength is greater. Significant changes in elongation only occur from 700 ℃ onwards, and the change in elastic modulus is not pronounced. The mechanical properties of different grades of steel after cooling from high temperature differ markedly, and LY160 steel exhibits notable changes in yield strength at relatively low temperatures (400 ℃). The experimental results match well with the fitting curves, and the fitting formulas allow for the rapid acquisition of the mechanical properties of LY160 steel after high-temperature exposure.
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