新型核电用SIMP马氏体耐热钢热变形行为研究

Study on Thermal Deformation Behavior of a New Type SIMP Heat Resistant Martensitic Steel Used for Nuclear Power

为研究新型核电用SIMP马氏体耐热钢的热变形行为,采Gleeble-3500热模拟试验机在900~1200℃以0.1~10 s^(-1)的应变速率进行了压缩变形试验。压缩变形后检测了钢的显微组织,并根据热塑性变形理论和试验数据绘制了钢的真应力-真应变曲线。结果表明:变形温度和应变速率明显影响SIMP钢热变形过程中的动态回复和动态再结晶的发生;在900℃左右压缩变形的钢主要发生动态回复,在1000℃压缩变形的钢发生动态再结晶,高于1100℃压缩变形的钢发生了完全再结晶;变形温度较高时,钢的流变应力曲线有明显的峰值,变形温度较低时,流变应力曲线上没有明显的峰值;SIMP钢的最适合的塑性变形温度为1100℃,应变速率为10 s^(-1)。

In order to investigate its thermal deformation behavior,a new type SIMP martensitic heat⁃resistant steel for nuclear power was subjected to compression deformation tests at temperatures ranging from 900 to 1200℃and at strain rates ranging from 0.1 to 10 s^(-1)via a Gleeble⁃3500 thermal simulation test machine.After compression deformation,the microstructure of the steel was detected,and the true stress⁃true strain curves for the steel were plotted on the basis of both thermoplastic deformation theory and test data.The results showed that(a)occurrences of dynamic recovery and dynamic recrystallization in SIMP steel during thermal deformation were affected obviously by the deformation temperature and strain rate;(b)the dynamic recovery occurred mostly in the steel compression⁃deformed at about 900℃,and the dynamic recrystallization occurred in the steel compression⁃deformed at 1000℃,and the complete recrystallization occurred in the steel compression⁃deformed at temperatures higher than 1100℃;(c)the flow stress curve of the steel exhibited obvious peak when the deformation temperature was higher,and did not exhibit obvious peak when the deformation temperature was lower;and(d)the preferable plastic deformation temperature and the strain rate were correspondingly 1100℃and 10 s^(-1)for SIMP steel.