液相线半连续铸造7075Al合金二次加热与触变成形  

STUDY ON THE REHEATING AND THIXOFORMING OF 7075 ALUMINUM ALLOY CAST BY LIQUIDUS SEMI- CONTINUOUS CASTING

作　　者：路贵民[1] 董杰[1] 崔建忠[1] 王平[1] 

机构地区：[1]东北大学材料电磁过程教育部重点实验室,沈阳110004

出　　处：《金属学报》2001年第11期1184-1188,共5页Acta Metallurgica Sinica

基　　金：国家自然科学基金资助项目59974009;中国博士后科学基金资助项目

摘　　要：研究了液相线半连续铸造的７０７５Ａｌ合金半固态浆料在不同温度下的液固相比、二次加热组织、触变成形性，以及热处理前后成形件的力学性能．结果表明，７０７５Ａｌ合金触变成形液相比为３０％－５０％时对应的温度区间为６００－６２０℃，二次加热可以将液相线半连续铸造７０７５Ａｌ合金锭坯中的蔷蔽状和近球状组织转化为球形晶粒组织，适合于半固态加工，组织最佳的条件是加热温度５８０℃左右，保温时间１５－３０ｍｉｎ，及加热温度６００℃左右，保温时间５－１５ｍｉｎ之间，加热到６００℃，保温１５ｍｉｎ后７０７５合金流动性成形性非常好，闭模锻造完全可以半固态成形，未经热处理的７０７５Ａｌ合金成形件强度极限达３５７．９ＭＰａ，Ｔ６热处理后强度极限达４６８ＭＰａ．The liquid fraction of liquidus semi-continuous casting (LSC) 7075 alloy at different temperatures, evolution of the reheating microstructures at different reheating temperatures, thixoformability and the mechanical properties of thixoforming products were studied. The results show that the best thixoforming temperature is 600-620 degreesC and the liquid fraction 30%-50%. Reheating can turn the rosette-shaped grains into spheroids which are suitable for thixoforming. The best reheating microstructures can be obtained at about 580 degreesC and the holding time about 15-30 min, or near 600 degreesC and 5-15 min. The good thixoformability of the billet corresponds to 600 degreesC reheating for 15 min. The ultimate strength of products forged in mould is 357.9 MPa, and 468 MPa after T6 treatment. Therefore, Liquidus semi-continuous casting is an efficient way for semi-solid slurry making, and together with its thixioforming are very hopeful for industralization.

关 键 词：液相半连续铸造 液相比 二次加热 半固态触变成形 组织 性能 铝合金 

分 类 号：TG292[金属学及工艺—铸造] TG249.7