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采用正交试验方法及力学性能测试研究了气缸盖用Al-Si-Cu系铝合金材料的热处理工艺,采用光学显微镜观察了试样热处理前后的显微组织。结果表明:在固溶温度等参数确定的前提下,时效温度是影响材料强度及伸长率的最主要因素。最佳的热处理工艺参数为:固溶温度(490±5)℃,保温5 h;淬火延迟时间≤15 s,淬火温度为(80±10)℃,淬火时间3~5 min;时效温度(160±5)℃,保温3 h。经该工艺处理后材料的抗拉强度达到300 MPa以上,屈服强度达到230 MPa以上,伸长率≥2%。铝合金经固溶时效处理后,针片状粗大的化合物转变为细小圆润的球状及短棒状,减轻了铸态组织中针状组织对基体的割裂作用,进而提升了基体的综合力学性能。
The heat treatment process of Al-Si-Cu aluminum alloy for cylinder head was studied by orthogonal test method and mechanical property test. The microstructure of the sample before and after heat treatment was observed by optical microscope. The results show that aging temperature is the most important factor affecting the strength and elongation of the material under the premise of the solution temperature and other parameters. The optimal heat treatment process parameters are: solution temperature (490 ± 5) ℃, holding time 5 h, quenching delay time 15 s, quenching temperature 80 ± 10 ℃, quenching time 3 ~ 5 min, aging temperature 160 ± 5) ℃, heat 3 h. After the process, the tensile strength of the material reaches more than 300 MPa, the yield strength reaches more than 230 MPa and the elongation is more than or equal to 2%. After solution treatment and aging treatment of aluminum alloy, the needle-like coarse compound turned into small round and spherical shape and short rod shape, which reduced the acicular structure of the as-cast microstructure and improved the mechanical properties of the matrix.