Sr+B+RE联合细化变质对Al-30Si合金热处理性能的影响

Effect of Refinement and Modification of Sr+B+RE on Heat Treatment of Al-30Si Alloy

通过正交试验、金相实验和硬度实验研究了Sr+B+RE联合细化变质后的Al-30Si合金的固溶温度、保温时间对合金显微组织及硬度的影响,得出了Sr+B+RE联合细化变质后的Al-30Si合金的最佳热处理工艺参数。结果表明,固溶温度与保温时间对合金显微组织与硬度均有影响。当保温时间一定时,随着固溶温度的升高,初晶硅溶入基体越来越充分,被基体分割的效果越来越明显,共晶组织变得粗大,圆整度变高,合金硬度提高。当固溶温度一定时,随着保温时间的延长,初晶硅溶入基体越来越充分,被基体分割的效果越来越明显,共晶组织变得粗大,圆整度变高,合金硬度提高,当温度达到540℃时,保温时间的延长使共晶组织圆整度变差,合金的硬度反而下降,固溶温度为540℃、保温时间为7h时硬度最高。Sr+B+RE联合细化变质后的Al-30Si合金的最佳热处理工艺参数为540℃×7h。

The effect of Al-30 Si alloy′s solution temperature and holding time on alloy microscopic structure and hardness after the joint refining and modification of Sr,B and RE was studied by orthogonal test,metallographic experiment and hardness test,which obtained the best heat treatment process parameters of Al-30 Si.It turned out that both solution temperature and holding time had an effect on alloy microscopic structure and hardness.When holding time was certain,primary silicon dissolved into matrix more fully with the rising of solution temperature,and the segmentation effect by matrix was more and more obvious.Eutectic structure became bulky and round,while the hardness of the alloy turned to be higher.When solution temperature was certain,primary silicon dissolved into matrix more fully with the prolongation of holding time,and the segmentation effect by matrix was more and more obvious.Eutectic structure became bulky and round,while the hardness of the alloy turned to be higher.When the solid temperature reached to 540 ℃,the roundness of the eutectic structure became worse with the prolongation of holding time,and the hardness of the alloy was down.540 ℃ of solid temperature with 7hours of holding time caused the highest hardness.The best heat treatment process parameters of Al-30 Si after the joint refining and modification of Sr,B and RE should be 540 ℃of solid temperat re with 7hours of holding time.