Na Wang Zhimin Zhou
材料科学技术（英文）
The semi-solid billet of 6061 aluminum alloy was prepared by the near-liquidus semi-continuous casting (LSC) with rosette or near-spheroide grains. The pre-deformation processing was applied before partial remelting to further improve the microstructure and properties of the semi-solid alloy. The effects of different processing parameters, such as holding temperature and holding time, on the semisolid microstructures during partial remelting have been investigated. It was found that the optimal partial remelting parameters should be 630°C and 10{15 min for 6061 alloy cold rolled with 60% reduction in height of pre-deformation. The coarsening rates were anasysed by Lifshitz-Slyozov-Wagner (LSW) theory. The pre-deformed 6061 alloy exhibits lower coarsening rate constants than that of the as-cast one, and also lower than other alloys processed by different method found in previous literature. It is because the coarsening rate is associated with the initial microstructure and composition of the alloy. The secondary phases in the alloy inhibit the migration of the liquid film grain boundaries. The microstructure obtained by using the combination of near-liquidus semicontinuous casting and pre-deformation treatment is better than that without pre-deformation processing, which demonstrates that the used method is promising for fabricating high quality semi-solid alloys.
关键词:
Semi-solid forming
,
Near-liquidus semi-continuous casting
,
6061 alloy
,
Pre-deformation
,
Partial remelting
,
Coarsening
王平
,
刘静
稀有金属材料与工程
采用金相显微镜和电子拉伸机,研究了6061合金半固态坯料的电磁半连续铸造、二次加热、触变模锻成形以及成形件热处理.结果表明:采用近液相线电磁半连续铸造技术制备的6061合金半固态坯料微观组织为均匀、细小非枝晶组织;低过热度浇铸时,临界晶核半径减小,此时在电磁场作用下,降低了熔体的温度梯度,促进了准固相原子团簇在熔体中形成,形核率增大;二次加热时,初生α-Al不断球化,淬火组织也呈圆整状,620士5℃、保温15 min,模具温度250～300℃,留模时间10～15 s,触变成形出表面光洁的成形件;经T5处理后,抗拉强度达到328 MPa,延伸率达到8％,大大高于压铸成形件的性能.半固态压铸成形由于成形速度高,溶体高速充型,造成成形件气孔率高,使成形件组织致密度不如半固态模锻成形件,这是半固态压铸件强度低、模锻件强度高的主要原因.
关键词:
6061合金
,
半连续铸造
,
重熔加热
,
触变模锻
,
性能
刘鑫刚
,
王国军
,
陈雷
,
孟冬凝
,
于琳琳
,
郭宝峰
,
毛天宏
材料热处理学报
借助DSC、SEM、EDS等手段分析了均匀化热处理工艺参数对6061铝合金组织与力学性能的影响规律.结果表明:铸态6061铝合金中析出相主要包括Mg2Si、β-Al5FeSi、β-Al5(FeMn) Si及少量的α-Al12(FeMn)3Si2.随均匀化加热温度升高,铸态合金枝晶网状组织变得不连续,且基体逐渐析出大量弥散相.当均匀化温度超过580℃时,基体出现复熔球,即合金出现过烧现象.加热温度在550 ～ 590℃范围内,合金的强度和塑性随均匀化加热温度的升高,呈先增大后减小的趋势,在575℃时达到最佳值;延长保温时间,合金的强度增大,而塑性则先减小后增大.
关键词:
6061铝合金
,
均匀化
,
显微组织
,
强度
,
塑性
