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采用Thermo-Calc软件对耐氯盐腐蚀高Cr钢(8.0%~11.0%)和中Cr钢(3.5%~6.5%)各相摩尔分数,N和Cr在各相中的质量分布进行了计算。结果表明,含N质量分数为0.03%~0.08%的高Cr钢在837~783℃时,析出Cr2N相且N几乎完全固溶其中,有7.8%Cr固溶于α中,0.7%Cr形成M23C6,剩余Cr形成Cr2N;Cr钢在870~773℃时,析出CrN相,645℃时CrN转变为Cr2N相,4%Cr固溶于α中,0.7%Cr形成M23C6,剩余Cr形成Cr2N。控制板条马氏体比例95%以上的条件是高Cr钢的临界冷速≥0.5℃/s,中Cr钢的冷速≥10℃/s。在10℃/s冷速下,中Cr钢中存在约3.5%的介于板条马氏体带之间的薄膜状残留奥氏体。为了减少中Cr钢混晶,采用单道次压缩热模拟试验,确立了实验钢的动态再结晶的临界条件,得出变形激活能和应力指数分别为234085 J/mol和1.79,并建立了实验钢的Z参数的表达式。
The mass fraction of N and Cr in each phase was calculated using Thermo-Calc software for the molar fraction of each phase of the chloride-resistant high Cr steel (8.0% ~ 11.0%) and the medium Cr steel (3.5% ~ 6.5%). The results show that the Cr2N phase is precipitated at 837 ~ 783 ℃ with N mass fraction of 0.03% ~ 0.08%. Almost completely dissolved and dissolved in the solution, 7.8% Cr dissolves in α and 0.7% Cr forms M23C6 , The remaining Cr to form Cr2N; Cr steel at 870 ~ 773 ℃, the precipitation of CrN phase, 645 ℃ CrN into Cr2N phase, 4% Cr solid solution in α, 0.7% Cr to form M23C6, the remaining Cr Cr2N. The condition of controlling the martensite ratio of the lath above 95% is that the critical cooling rate of the high Cr steel is not less than 0.5 DEG C / s and the cooling rate of the medium Cr steel is not less than 10 DEG C / s. At a cooling rate of 10 ° C / s, about 3.5% of the retained austenite in the film exists between the lath martensite bands in the medium Cr steel. In order to reduce the Cr content in Cr steel, the critical condition of dynamic recrystallization of experimental steel was established by single pass compression thermal simulation. The activation energy and stress exponent of deformation were respectively 234085 J / mol and 1.79, and the experiment Steel Z parameter expression.