转动微动磨损条件下7075铝合金的局部疲劳行为研究

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Rotational fretting wear tests of 7075 aluminum alloy against 52100 steel ball under the different angular displacement amplitudes were carried out on a new rotational fretting wear testing rig. The initiation and propagation behavior of local fatigue cracks induced by rotational fretting wear were studied based on the micro-analysis of surface and profile morphologies of wear scars. The results show that the fatigue cracks distribute mainly in the mixed fretting regime （MFR） under the condition of rotational fretting wear, and most of them propagate into the matrix alloy. In the MFR, the material failure mechanism mainly was as a result of fatigue crack initiation and propagation accompanied with particles detachment by delamination. In the partial slip regime （PSR） , the fatigue crack expanded parallel to the direction of the surface and the fretting damages were mainly slight delamination. In the slip regime （SR） , the fatigue effect weakened and the wear of material was dominant during the competition process between the local contact fatigue and wear. In additional, the formation of local fatigue crack was closely related to the central convexity under the rotational fretting wear.在新型转动微动磨损试验机上，进行了7075铝合金与GCr15钢球配副在不同角位移幅值下的转动微动磨损实验。在磨痕表面形貌及剖面微观分析的基础上，研究了转动微动磨损的局部疲劳裂纹萌生和扩展行为。结果表明：转动微动磨损条件下疲劳裂纹主要分布于混合区，大量的裂纹向基体内部扩展，混合区材料的失效形式主要表现为裂纹的萌生和扩展，并伴随因疲劳磨损所致的片状剥落；在部分滑移区，疲劳裂纹萌生后平行于表面方向扩展，微动损伤主要表现为材料的轻微剥落；在滑移区，在局部接触疲劳和磨损的竞争过程中，疲劳效应减弱且材料磨损占支配地位。此外，疲劳裂纹的形成与转动微动的中心隆起有密切关系。