Cast iron alloys with low production cost and quite good mechanical properties are widely used in the automotive industry.To study the mechanical behavior of a typical ductile cast iron(GJS-450)with nodular graphite,u...Cast iron alloys with low production cost and quite good mechanical properties are widely used in the automotive industry.To study the mechanical behavior of a typical ductile cast iron(GJS-450)with nodular graphite,uni-axial quasi-static and dynamic tensile tests at strain rates of 10^(-4),1,10,100,and 250 s^(-1)were carried out.In order to investigate the influence of stress state on the deformation and fracture parameters,specimens with various geometries were used in the experiments.Stress strain curves and fracture strains of the GJS-450 alloy in the strain rate range of 10^(-4)to 250 s^(-1)were obtained.A strain rate-dependent plastic flow model was proposed to describe the mechanical behavior in the corresponding strain-rate range.The available damage model was extended to take the strain rate into account and calibrated based on the analysis of local fracture strains.Simulations with the proposed plastic flow model and the damage model were conducted to observe the deformation and fracture process.The results show that the strain rate has obviously nonlinear effects on the yield stress and fracture strain of GJS-450 alloys.The predictions with the proposed plastic flow and damage models at various strain rates agree well with the experimental results,which illustrates that the rate-dependent plastic flow and damage models can be used to describe the mechanical behavior of cast iron alloys at elevated strain rates.The proposed plastic flow and damage models can be used to describe the deformation and fracture analysis of materials with similar properties.展开更多
30CrMnSiA合金钢的室温成形性能差,为探究30CrMnSiA材料电流辅助成形的可行性,基于不同试验参数的电流辅助拉伸试验,研究了温度及脉冲电流参数(电流密度、脉冲占空比和频率)对30CrMnSiA流动应力的影响规律。研究表明:30CrMnSiA的强度及...30CrMnSiA合金钢的室温成形性能差,为探究30CrMnSiA材料电流辅助成形的可行性,基于不同试验参数的电流辅助拉伸试验,研究了温度及脉冲电流参数(电流密度、脉冲占空比和频率)对30CrMnSiA流动应力的影响规律。研究表明:30CrMnSiA的强度及伸长率随温度及电流密度的升高而下降,受脉冲占空比和频率影响不大;脉冲电流能抑制动态应变时效的强化作用,并促进碳化物的析出,使材料塑性下降。基于Voce模型基础,建立了考虑应变速率、温度及脉冲电流参数影响的30Cr Mn Si A电流辅助流动应力模型。利用该模型计算的结果与试验值吻合较好,说明该模型能准确预测材料在电流辅助条件下的流动应力。展开更多
基金Supported by National Natural Science Foundation of China (Grant Nos.12202205,U1730101)the Federal Ministry of Economic Affairs and Energy (BMWi)via the German Federation of Industrial Research Associations‘Otto von Guericke’e.V. (AiF) (IGF-Nr.19567N)Forschungsvereinigung Automobiltechnik e.V. (FAT)。
文摘Cast iron alloys with low production cost and quite good mechanical properties are widely used in the automotive industry.To study the mechanical behavior of a typical ductile cast iron(GJS-450)with nodular graphite,uni-axial quasi-static and dynamic tensile tests at strain rates of 10^(-4),1,10,100,and 250 s^(-1)were carried out.In order to investigate the influence of stress state on the deformation and fracture parameters,specimens with various geometries were used in the experiments.Stress strain curves and fracture strains of the GJS-450 alloy in the strain rate range of 10^(-4)to 250 s^(-1)were obtained.A strain rate-dependent plastic flow model was proposed to describe the mechanical behavior in the corresponding strain-rate range.The available damage model was extended to take the strain rate into account and calibrated based on the analysis of local fracture strains.Simulations with the proposed plastic flow model and the damage model were conducted to observe the deformation and fracture process.The results show that the strain rate has obviously nonlinear effects on the yield stress and fracture strain of GJS-450 alloys.The predictions with the proposed plastic flow and damage models at various strain rates agree well with the experimental results,which illustrates that the rate-dependent plastic flow and damage models can be used to describe the mechanical behavior of cast iron alloys at elevated strain rates.The proposed plastic flow and damage models can be used to describe the deformation and fracture analysis of materials with similar properties.
文摘30CrMnSiA合金钢的室温成形性能差,为探究30CrMnSiA材料电流辅助成形的可行性,基于不同试验参数的电流辅助拉伸试验,研究了温度及脉冲电流参数(电流密度、脉冲占空比和频率)对30CrMnSiA流动应力的影响规律。研究表明:30CrMnSiA的强度及伸长率随温度及电流密度的升高而下降,受脉冲占空比和频率影响不大;脉冲电流能抑制动态应变时效的强化作用,并促进碳化物的析出,使材料塑性下降。基于Voce模型基础,建立了考虑应变速率、温度及脉冲电流参数影响的30Cr Mn Si A电流辅助流动应力模型。利用该模型计算的结果与试验值吻合较好,说明该模型能准确预测材料在电流辅助条件下的流动应力。
