【摘要】 建立了描述近液相线半连续铸造过程的温度场模型和微观组织演变模型,通过固相率变化将介观尺度上的Cellu-lar Automaton(CA)计算和宏观尺度上的有限差分耦合起来,实现合金凝固组织演变的多尺度模拟。通过模拟和试验研究了6061合金在不同浇注温度和铸造速度下初生相的演变。结果表明,浇注温度对初生相形貌的影响最大,当浇注温度在液相线附近并且保温一段时间,初生相为理想的近球状组织;6061合金的最佳工艺条件是浇注温度为940K、铸造速度为0.02mm/s、冷却水强度为0.05m3/min,与试验吻合。更多还原

【Abstract】 This paper established the thermal field model and phase transformation model for near-liquidus casting process. The solid fraction was used to couple the macroscale and mesoscale calculations. The evolution of the morphology of primary phase of 6061 alloys was simulated and experimentally studied under different conditions, e.g. pouring temperature, casting velocity, cooling intensity etc. The results show that the pouring temperature has the largest effect on the morphology of primary phase. When isothermally holding a while and then pouring near the liquidus, the morphology of primary phase is ideal globular. It is shown that the desired semisolid structure of 6061 alloy can be obtained under the conditions of 940K pouring temperature, 0.05 m3/min cooling intensity and 0.002 m/s casting velocity.更多还原