Abstract:

To investigate the influences of plasma treatment on the mechanics properties of 45 steel， the changes of mechanics properties of 45 steel before and after treatment were studied by combining experiments and molecular dynamics simulation. The test results show that the hardness and tensile mechanics properties of 45 steel are obviously decreased after plasma treatment. Under the treatment durations of 1， 5 and 10 min， the nano-hardnessis decreased by 12%， 21% and 28% respectively， and the longer the treatment time， the better the modification effect， and the duration of the modification effect is more than 20 h. When the thickness of tensile specimens is as 0.1， 0.15 and 0.2 mm， the tensile strength decreases by 3.3%， 4.5% and 5.3%， and the elongation after fracture decreases by 39.69%， 42.17% and 42.49%， respectively. The molecular dynamics simulation results show that the number and strength of Fe-Fe bonds in 45 steel are reduced after plasma modification， resulting in the reduction of yield strength and surface hardness of the materials， which is basically consistent with the experimental results.

Key words: plasma, molecular dynamics, nano-hardness, tensile strength, 45 steel

摘要：

为探明等离子体处理对45钢材料力学性能的影响规律，采用试验与分子动力学模拟相结合的方法，对处理前后45钢材料力学性能的变化进行对比研究。试验结果表明：等离子体处理后，45钢材料硬度和拉伸力学性能明显下降；在1、5、10 min的处理时间下，纳米硬度分别降低12%、21%和28%，且处理时间越长，改性效果越好，并且改性效果的持续时间均长达20 h以上；拉伸试样厚度为0.1、0.15、0.2 mm时，抗拉强度分别降低3.3%、4.5%和5.3%，断后伸长率分别降低39.69%、42.17%和42.49%。分子动力学仿真结果表明，等离子体改性降低了45钢材料中Fe-Fe键的数量和强度，导致材料屈服强度和表面硬度降低，与试验所得结果基本一致。

关键词: 等离子体, 分子动力学, 纳米硬度, 抗拉强度, 45钢