Microstructure and Thermal Fatigue Properties of A356 Alloy for Automotive Engine

Liu Haihong; Su Lei; Dou Shasha

doi:10.15980/j.tzzz.2017.09.025

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Microstructure and Thermal Fatigue Properties of A356 Alloy for Automotive Engine
Vol. 37, Issue 9, Pages: 1022-1025(2017)
Published： 2017 ，
DOI： 10.15980/j.tzzz.2017.09.025

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[1]刘海红,苏磊,窦沙沙.A356合金的组织与热疲劳性能研究[J].特种铸造及有色合金,2017,37(09):1022-1025.

Liu Haihong, Su Lei, Dou Shasha. Microstructure and Thermal Fatigue Properties of A356 Alloy for Automotive Engine. [J]. Special Casting & Nonferrous Alloys 37(9):1022-1025(2017)
[1]刘海红,苏磊,窦沙沙.A356合金的组织与热疲劳性能研究[J].特种铸造及有色合金,2017,37(09):1022-1025. DOI： 10.15980/j.tzzz.2017.09.025.

Liu Haihong, Su Lei, Dou Shasha. Microstructure and Thermal Fatigue Properties of A356 Alloy for Automotive Engine. [J]. Special Casting & Nonferrous Alloys 37(9):1022-1025(2017) DOI： 10.15980/j.tzzz.2017.09.025.

摘要

以A356合金为研究对象

采用复合细化变质、微合金化和T6热处理的方法制备了5种A356合金

研究了合金的力学性能、显微组织和不同温度幅下的热疲劳性能

并分析了热疲劳裂纹的生长行为和产生机理。结果表明

经过复合细化变质、微合金化和T6热处理可以使A356合金的力学性能得到提高;经过T6热处理后

复合细化变质和复合细化变质+微合金化的A356合金中共晶Si的形态由针片状转变为颗粒状

共晶Si棱角圆整化程度提高提高

铸态A356合金的热疲劳寿命得到延长;在温度幅下限不变的前提下

合金的热疲劳寿命随着温度幅上限的提高而逐渐降低;经过复合细化变质+微合金化+T6热处理后合金的裂纹萌生和扩展速率最低

热疲劳寿命最长。

Abstract

Five kinds of A356 alloys were prepared by compound refining modification

micro-alloying and T6 heat treatment.The mechanical properties

microstructure and thermal fatigue properties of A356 alloys under different temperatures were investigated

and the growth behavior and mechanism of fatigue crack were analyzed.The results reveal that

the mechanical properties of as-cast A356 alloys can be improved by compound refining modification

micro-alloying and T6 heat treatment.After T6 heat treatment

the morphology of the eutectic silicon phase is changed from needle plate to granular and the degree of roundness of eutectic silicon was improved in A356 alloy with complex refinement and composite refinement & micro-alloying.The thermal fatigue crack initiation life of as cast A356 alloy can be improved by composite refinement modification

micro-alloying and T6 heat treatment.The thermal fatigue life of the alloy is decreased with the increase of the temperature amplitude limit when the temperature amplitude limit is constant.The crack initiation and propagation rate of the alloy E after composite refinement modification + micro-alloying+ T6 heat treatment is the lowest and the thermal fatigue life is the longest.