ZTC4钛合金机匣构件离心铸造过程的数值模拟

采用数值模拟方法,研究ZTC4合金机匣离心铸造的充型和凝固过程,分析了离心转速、浇注温度和铸型预热温度对熔体充填过程流动场、凝固过程温度场和应力场的影响,并预测了缺陷的分布.结果表明,随离心转速提高,熔体充型速度无明显变化,但柯氏力作用更加明显,铸型中熔体流股变细；熔体过热度低于30℃时,铸件出现明显的浇不足缺陷；铸型预热温度是影响铸件残余应力的主要因素,而离心转速和熔体过热度的影响次之；铸件最后凝固的较厚部位容易出现缩松、缩孔缺陷,且其位置与X射线检测结果较吻合.

Numerical Simulation of Centrifugal Casting Process of ZTC4 Ti Alloy Case

Numerical simulation was employed to investigate the filling and solidification process of centrifugal casting ZTC4 case. Influences of pouring temperature of the melt, centrifugal rotational speed and preheating temperature of the mould on the flow fields during filling process and the temperature fields as well as stress fields during solidification process were analyzed. The formation of defects in centrifugal casting ZTC4 case was approached. The simulation results indicate that with the increase of the centrifugal rotational speed, although change of the mould filling rate can be ignored, the effect of Coriolis force on the melt becomes more significant, resulting in the thin of molten flow in the mould. When the superheat of the melt is lower than 30 ℃, the misrun can be observed. The factors influencing residual stress of the castings are as follows in importance: preheating temperature of mould, centrifugal rotation velocity, and melt super-heating. The shrinkage porosity (hole) defects are prone to easily appear in the thicker position of the castings, and their location is in accordance with the X-ray inspection results.