Study On Hot Deformation Behavior Of2Cr13Steel

With high strength and toughness, creep resistance, good high temperature oxidation resistance and corrosion resistance, the9%-12%Cr heat-resistant steel is becoming the major equipment and the updating material used in the thermal power plant. With the good integrated properties,2Cr13steel is a kind of heat-resistant martensitic stainless steel which is used widely to manufacture the blade of the steam turbine. However, there are lots of difficulties in the hot working of2Cr13steel. For example, the flow stress and deformation temperature of2Cr13steel is high and the processing temperature range is too narrow. Accordingly, the research of hot working processing of2Crl3steel with the method of thermal simulation test has important academic and engineering significance.In this thesis, the hot deformation behavior of2Cr13steel has been studied on a thermo-mechanical simulator and its microstructural evolution observed by different kind of microscopes. The following research results could be obtained.(1) The effect of hot working processing parameters on flow stress of2Cr13steel has been studied through the single-pass compression test. During the process of hot deformation, the flow stress of2Crl3steel increases with decreasing deformation temperature and increasing strain rate. Moreover, the influence of strain on flow stress is more complex, not a simple monotonic relationship. Besides, a mathematical model of flow stress for2Cr13steel has been established, which has a good fitting accuracy.(2) The law of occurrence of DRX has been revealed through the microstructure observation of single-pass compression samples under different deformation conditions. DRX is more likely to happen when deformation temperature is high and strain rate is low. Combined with electron microprobe it’s also found the law that the size and morphology of carbide precipitation in grain boundaries and the hardness after aging get changed with different aging temperatures.(3) A high temperature constitutive equation and flow stress equation have been established on the basis of Zener-Hollomon equation and the hot deformation activation energy of2Cr13steel has been calculated.(4) The volume fraction of static recrystallization for2Crl3steel (SRX) has been calculated through0.2%off-set method. The law of effect of hot working processing parameters on the rate of SRX has been analyzed. The deformation temperature, the strain rates and the stress is higher, the volume fraction of the static recrystallization is higher, The SRX kinetics equation has been established based on Avrami equation.(5) The basic theory of dynamic material model (DMM) has been studied. The hot processing maps for2Cr13steel with different strains have been established by the data from single-pass compression. The best hot working temperatures range from1050℃to1040℃and the strain rates range from0.01s-1to0.5s-1.