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对不同工艺处理的铝硅合金ZAlSi7Cu4,用自约束型热疲劳试验机进行25～350℃的热循环试验,研究了不同处理工艺对该材料热疲劳性能的影响。通过光学显微镜和扫描电镜观察了试样的热疲劳裂纹形貌,分析了合金热疲劳损伤机制。结果表明,在350℃下,经过T6处理的该材料相对其他处理工艺具有更好的热疲劳性能。颗粒的位向会影响裂纹的扩展路径;氧化孔洞的曲率半径较大时可减缓裂纹在孔洞边缘的萌生扩展;材料在T6、铸态淬火+时效、铸态3种处理工艺下的试样表面硬度随着热循环次数的增加总体呈现下降趋势,而在裂纹萌生前的一段周次内,T6和铸淬+时效试样的硬度均微弱回升。
The thermal cycling test of aluminum-silicon alloy ZAlSi7Cu4 with different process was carried out with a self-restraining thermal fatigue tester at 25 ~ 350 ℃. The effects of different treatment processes on the thermal fatigue properties of the material were studied. The thermal fatigue crack morphology was observed by optical microscope and scanning electron microscope, and the thermal fatigue damage mechanism of the alloy was analyzed. The results show that at 350 ℃, the T6-treated material has better thermal fatigue properties than other treatment processes. When the radius of curvature of the oxidized hole is large, the initiation and propagation of the crack on the edge of the hole can be slowed down. The surface of the specimen under the three treatments of T6, as-cast quenching and aging, as-cast The hardness decreases with the increase of the number of thermal cycles, while the hardness of T6 and cast-quenched + aged specimens rebound slightly during the period before crack initiation.