机械

温度是影响45钢材料力学和热学性能的重要因素。因此，通过开展不同温度下的准静态拉伸等一系列材料力学及热学性能测试试验，研究了温度对45钢材料性能的影响规律。力学性能试验结果表明，在20～900℃内，随着温度的升高，拉伸应力-应变曲线的屈服平台和硬化段逐渐消失，曲线趋于平缓，抗拉强度在900℃时降低90%，且断后伸长率与断面收缩率显著提升，表明温度升高促进了45钢材料的塑性变形；45钢材料杨氏模量和泊松比在700℃时分别降低至常温的60%与28%，刚度明显降低。热学性能试验表明，在20～800℃内，热导率在20～300℃范围内基本保持在常温水平，而后随温度升高有所降低；比热容随温度的升高逐渐增大，在700℃时超过常温时的两倍；线膨胀系数整体波动较小，在700℃时最高。

Temperature is an important factor affecting the mechanical and thermal properties of 45 steel. In this paper, the effect of temperature on the properties of 45 steel is studied through a series of mechanical and thermal properties tests of materials such as quasi-static stretching at different temperatures. The mechanical properties test results show that the yield platform and hardening section of the tensile stress-strain curve gradually disappear with the increase of temperature in the range of 20-900 ℃, the curve tends to be flat, the tensile strength decreases by 90% at 900 ℃, and the elongation and section shrinkage after fracture increase significantly, indicating that the temperature increase leads to the plastic deformation of 45 steel. Young's modulus and Poisson's ratio of 45 steel are reduced to 60% and 28% of room temperature respectively at 700 ℃, and the stiffness of 45 steel is significantly reduced. The thermal performance test shows that the thermal conductivity basically stays at room temperature in the range of 20-800 ℃, and then decreases with the increase of temperature. The specific heat capacity increases gradually with the increase of temperature, and is more than twice of normal temperature at 700 ℃. The linear expansion coefficient exhibits minor fluctuations and reaches the highest value at 700 ℃.