摘要
True stress?true strain curves of Incoloy028alloy at high temperature and strain rate were investigated by hot compression test.These curves show that the maximum flow stress decreases with the increase in temperature and the decrease in strain rate.FEM simulation was employed to investigate the influence of temperature,extrusion speed and friction coefficient on the extrusion load,stress,strain and strain rate in the extrusion process.The increase of extrusion temperature results in decrease of load and deformation resistance,but has little influence on strain and strain rate.When extrusion speed changes between200and350mm/s,no obvious change about extrusion load can be found.Sharp peak value up to42500kN emerges in the extrusion load curve and the extrusion process becomes unstable seriously when extrusion speed rises up to400mm/s.Both stress and strain rate increase with the raise of extrusion speed.When friction coefficient is between0.02and0.03,deformation resistance is about160MPa and the strain rate can be limited below70s?1.Successful production of Incoloy028tube verifies the optimized parameters by FEM simulation analysis,and mechanical tests results of the products meet the required properties.
采用热压缩实验方法研究Incoloy028合金在高温和高应变速率下应力-应变曲线。应力-应变曲线表明,峰值应力随着温度的升高和应变速率的下降而降低。采用有限元模拟方法研究挤压过程中温度、挤压速度和摩擦因数对挤压载荷、应力、应变和应变速率的影响,提高挤压温度可以降低挤压载荷和变形抗力,但对应变和应变速率的影响较小。当挤压速度在200~350 mm/s之间变化时,挤压载荷没有发生明显变化;当挤压速度达到400 mm/s时,挤压突破力达到42500 k N,挤压过程极不稳定。随着挤压速度的增大,应力和应变速率增大。当摩擦因数在0.02~0.03之间变化时,变形抗力约为160 MPa,挤压过程中应变速率可以控制在70 s^(-1)以下。生产试验成功验证了采用有限元方法优化后的挤压工艺参数,产品的力学实验结果满足性能要求。
基金
Project(50925417)supported by the National Science Fund for Distinguished Young Scholars of China
