双金属履带板挤压铸造成形技术研究

Production of Bimetal Track Plate by Squeezing Casting

采用数值模拟,研究了不同成形温度和不同热处理工艺对双金属履带板挤压铸造成形的影响。研究表明,履带板首先凝固位置为钢骨架和模具接触位置,也是应力集中的位置,缩松等缺陷主要出现在最后凝固的厚大部位。挤压铸造可以完成双金属履带板钢铝复合成形,铸件没有观察到缩松和裂纹等缺陷;铸件组织为典型的近球形,分布均匀细小,钢铝界面处存在部分细晶区和混晶区,热处理后合金组织晶界平滑,晶间相消失;热处理后部分钢铝界面产生分离现象,分离距离为2～6μm;高强铝合金基体一级固溶热处理后硬度(HB)为165,二级固溶热处理后达到180。

The effects of different forming temperatures and different heat treatment processes on squeezing casting bimetal track plate were investigated by numerical simulation.The results reveal that the track plate is first solidified ahead at the contact position of the steel skeleton and mould,which is also the stress concentration position.The shrinkage defects,such as porosity,may appear in the thick and large position of the final solidification.The steel and aluminum composite forming of the bimetal track plate can be realized by squeezing casting with absence of defects such as shrinkage and crack.The microstructure of the squeezing castings presents typically near spherical structure with the uniform and fine distribution.There exist some fine grain regions and mixed crystal areas at the interface of the steel and aluminum.The grain boundary of the alloy is smooth after heat treatment and the intergranular phase disappears.After heat treatment,the interface of steel and aluminum is separated slightly with about 2~6μm.The Brinell hardness of high strength aluminum alloy after first stage solid solution reaches 165 HB,and it reaches 180 HB after the two-stage solid solution treatment.