高速微粒轰击对微弧氧化铝合金疲劳性能的影响

以获取高性能微弧氧化陶瓷膜,且不降低基体铝合金的抗疲劳性能为目标,采用高速微粒轰击处理工艺和微弧氧化处理工艺制备了未处理、高速微粒轰击处理、微弧氧化处理、高速微粒轰击+微弧氧化处理复合处理4种状态的试样,通过疲劳试验机对其疲劳寿命进行了测试;同时,采用TEM和XRD残余应力测试仪等分析方法对试样的表层微观组织结构和残余应力进行了观察与测试。结果表明:加载载荷较高时,4种试样疲劳寿命基本相同,寿命较短;加载载荷较低时,微弧氧化处理铝合金的疲劳寿命明显低于未处理试样,高速微粒轰击处理导致的微观组织结构细化和形成的残余压应力可以有效抑制疲劳裂纹的萌生和扩展,使未处理和微弧氧化铝合金的疲劳寿命均得到有效提高,这2种高速颗粒轰击处理过的试样的疲劳寿命均高于未处理试样,这表明高速颗粒轰击强化处理可有效提高低应力水平时微弧氧化铝合金的疲劳寿命。

Effect of High-speed Particles Bombarding Pre-treatment on the Fatigue Properties of Micro-arc Oxidation Aluminum Alloy

In order to obtain the micro arc oxidation ceramic coatings of high performance and not to reduce the fatigue properties of aluminum alloy, 4 kinds surface conditions of aluminum alloy samples with untreated, high-speed fine particles bombarding treated, micro-arc oxidation treated, high-speed fine particles bombarding + micro-arc oxidation combining treated were prepared by high-speed fine particles bombarding technology and micro-arc oxidation (MAO) technique, and the fatigue lives of these samples were tested by universal fatigue test machine. At the same time, the surface layer microstructure and surface residual stress of these samples were observed and tested by TEM and XRD residual stress tester. Results show that all the surface conditions of the 4 kinds of samples had almost the same shorter fatigue life at high loads, but the fatigue life of these samples with micro-arc oxidation treatment was the shortest among all the samples at low loads, and it was significantly shorter than the untreated samples. The microstructure refinement and residual compressive stress resulted by high-speed fine particles bombarding treatment could effectively suppress the initiation and propagation of fatigue crack, so the fatigue life of the samples of high-speed fine particles bombarding treatment before and after micro-arc oxidation treatment were all improved, and the fatigue life of the two kinds of samples were both longer than the untreated samples, which shows that high-speed fine particles bombardment strengthening treatment could effectively improve the fatigue life of micro-arc oxidation aluminum alloy at lower stress level.