激光冲击强化MB8镁合金的工艺分析及摩擦磨损性能研究

目的 通过激光冲击强化技术的加工硬化效应改变MB8镁合金表面硬度及粗糙度，显著提高其抗磨损性能。方法 在不同功率密度、搭接率、冲击次数下对MB8镁合金激光冲击强化处理，通过非球面测量仪和显微硬度计分析材料表面粗糙度和显微硬度的影响规律，结合不同载荷下滑动摩擦磨损试验后的电镜图像，揭示激光冲击强化改变镁合金材料粗糙度、硬度从而影响耐磨性能的机理。结果 经激光冲击处理后镁合金硬度明显提高，表面硬度最大增幅达30.2%，同时形成了梯度硬化层。随着材料硬度的提升，其质量磨损率明显下降，耐磨损程度得到了显著改善，强化后镁合金的平均质量磨损率降幅可达28.73%。结论 试验冲击区域的粗糙度与激光功率密度呈正相关，与搭接率呈负相关，粗糙度随着冲击次数呈现先下降后升高的变化趋势。材料的硬化程度随着激光功率密度、搭接率和冲击次数的提高而增大，冲击次数的影响最为明显，激光功率密度次之，搭接率的影响最弱。低载条件下材料以磨粒磨损为主，而在高载荷条件下材料磨损过程伴随着疲劳磨损，强化效果有限。

Process Analysis and Friction Wear Performance Study of Laser Impact Strengthened MB8 Magnesium Alloy

Magnesium alloy due to its high specific strength, specific stiffness and good electrical conductivity, thermal conductivity and electromagnetic shielding properties and in the aerospace, weapons industry, nuclear industry and other military high-end fields have been widely used, known as the "21st century green engineering materials". However, its low strength and hardness make it susceptible to wear and fatigue failure under complex service conditions, which seriously affects the safety and reliability of the structure. Laser impact peening is a surface modification technique that uses the force effect of laser-induced shock waves to cause plastic deformation and residual compressive stress in metallic materials, thereby improving the overall mechanical properties of the material. This paper investigates the effect of laser impact peening on the wear and fatigue resistance of MB8 magnesium alloy. The main research work and conclusions are as follows.1. The changes in surface morphology and roughness of MB8 magnesium alloy during laser impact with different impact parameters. The roughness of the impact area was found to be positively correlated with the laser power density and negatively correlated with the lap rate, while the roughness showed a trend of decreasing and then increasing when the number of impacts was 1, 2 and 3 times respectively. 2, using different impact parameters of laser impact when the MB8 magnesium alloy hardness change law. After the laser impact treatment of magnesium alloy hardness significantly increased, the maximum increase in surface hardness of 30.2%, while the formation of a gradient hardening layer. As the hardness of the material increases its mass wear rate decreases significantly and the degree of wear resistance is improved significantly, with the average mass wear rate of the strengthened magnesium alloy decreasing by up to 28.73%. The hardening degree of the material increases with the increase of laser power density, lap rate and impact number, the impact number has the most obvious effect, the laser power density is the second, the lap rate has the weakest effect.3. The effect of laser impact on the tribological properties of magnesium alloys under different loads was investigated. After laser impact, the mass wear rate of the material is significantly reduced, and the wear resistance is significantly improved, and because the material is mainly abrasive wear under low load and low speed conditions, and laser impact can make the material hardness significantly increased, so its wear resistance strengthening effect is more obvious. However, under high load conditions the material wear process is accompanied by fatigue wear and thus the strengthening effect is limited.