含4.35%铜抗菌不锈钢的热变形行为

Hot deformation behavior of antibacterial stainless steel containing 4.35%copper

含铜奥氏体不锈钢具有优异的抗菌性能而广泛应用在食品加工、医疗等领域,然而铜的加入会显著影响不锈钢的加工性能。用Gleeble-3800热模拟试验机对含铜4.35%奥氏体抗菌不锈钢进行了单道次等温热压缩试验,研究了不锈钢在变形温度为900~1150℃、应变速率为0.01~10 s^(-1)和变形量为50%下的高温变形行为,构建了反映其材料特性的本构方程,使用金相显微镜观察了热变形后的微观组织,分析了各变形工艺下的微观组织演化规律,为含铜不锈钢的加工成型工艺及组织优化提供了理论参考。结果表明,4.35%Cu-304L钢的流动应力对变形工艺是敏感的,应力随着变形温度的升高和应变速率的降低而减小。采用得到的应力应变曲线建立了一种基于Arrhenius的5阶多项式拟合的应变补偿本构模型,根据此模型计算了相关系数R和平均相对误差AARE分别为0.972和9.03%,这表明所构建模型可以准确地反映含铜不锈钢的流动行为。结合微观组织发现较高的温度和较快的应变速率有利于再结晶的发生,由于0.01 s^(-1)低应变速率提供的变形能低,在变形温度为1100℃、应变速率为0.01 s^(-1)时仍存在初始变形晶粒;在变形温度为900℃、应变速率为10 s^(-1)下的晶粒畸变严重,且存在明显的由位错塞积形成的变形带,该变形条件下易导致裂纹的发生;在变形温度为1150℃、应变速率为1和10 s^(-1)下晶粒细化且均为等轴晶,这表明发生了完全再结晶。因此,针对4.35%铜不锈钢应考虑以变形温度为1150℃、应变速率为1和10 s^(-1)作为其热加工范围。

Austenitic stainless steel containing copper has excellent antibacterial properties and is widely used in food processing,medical and other fields.However,the addition of copper will significantly affect the processability of stainless steel.The single pass isothermal compression test of 4.35%austenitic antibacterial stainless steel containing copper was carried out by Gleeble-3800 thermal simulation test machine.The high temperature rheological behavior of stainless steel at deformation temperature 900-1150℃,deformation rate 0.01-10 s^(-1)and deformation amount 50%was studied.The constitutive equation reflecting the material characteristics is constructed,the microstructure after hot deformation is observed by metallographic microscope,and the microstructure evolution law under each deformation process is analyzed,which provides a theoretical reference for the plastic forming process and microstructure optimization of copper containing stainless steel.The results show that the flow stress of 4.35%Cu-304 L steel is sensitive to the deformation process,and the stress decreases with the increase of deformation temperature and the decrease of strain rate.A strain compensated constitutive model based on Arrhenius fifth order polynomial fitting is established by using the stress-strain curve.According to this model the correlation coefficient(R)and average relative error(AARE)are calculated to be 0.972 and 9.03%respectively,indicating that the constructed model can accurately reflect the flow behavior of copper containing stainless steel.Combined with the microstructure,it is found that higher temperature and faster strain rate are conducive to the occurrence of recrystallization.Due to the low deformation energy provided by 0.01 s^(-1)low strain rate,there are still initial deformed grains at 1100℃/0.01 s^(-1).At 900℃/10 s^(-1),the grain distortion is serious,and there is an obvious deformation band formed by dislocation stacking,which is easy to lead to cracks.At the strain rates of 1150℃/1 s^(-1)and 10 s^(-1),the grains are refined and equiaxed,indicating complete recrystallization.Therefore,for 4.35%copper stainless steel,1150℃/1 s^(-1)and 10 s^(-1)should be considered as its hot working range.