基于流变学模型的铸钢试件凝固过程应力应变数值模拟

Stree strain Simulation of Cast Steel Test Bar by Rheological Model During Solidification

建立了铸件凝固过程热应力模拟的一维流变学本构方程，并且对一端受约束一端带热节的铸钢试棒进行了数值模拟，进而研究了热裂机理。模拟结果表明，随着凝固过程的进行，在热节处粘塑性（Ｂｉｎｇｈａｍ）体的应变急剧增大而弹性应变急剧减小。浇注温度和砂型初始温度越高，热节处粘塑性应变越大，而热应力越小。并且热节处表观粘度随凝固进行逐渐增大，在凝固末期急剧增大。因此粘塑性应变决定了热裂的产生，并且热裂发生在凝固末期。

The unidimensional constitutive equations of rheological model have been established and stress and strain fields of cast steel test bar with hot spot at one end was calculated. The simulation results show that plastic strain (strain of Bingham body) concentrates and elastic strain (strain of Hooke body) declines at the hot spot. The higher the pouring temperature and initial mold temperature are, the larger the plastic strain while the smaller the thermal stress is. They become server with the increase of pouring temperature and initial mold temperature. And the apparent viscosity at the hot spot increases with time and increases dramatically at the last period of solidification. Therefore, it is the plastic strain but not the thermal stress playing an important role in determination of the occurrence of hot tearing which develops during the last period of solidification.