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通过金相显微镜、扫描电镜、电子探针显微分析、透射电镜及热力学计算软件研究C和N含量对铸态及时效态18Mn18Cr高氮钢析出相特征及形成机制的影响.研究发现在铸态,随C/N质量比降低,析出相依次为Cr23C6相、σ相和Cr2N相.增加C或N含量可分别促进Cr23C6相和Cr2N相析出.C和N含量影响实验钢凝固模式及不稳定铁素体相共析分解产物.18Mn18Cr0.44N钢凝固模式为AF模式,不稳定铁素体相共析分解反应为δ→σ+γ2(0.025%C)和δ→γ2+Cr23(CxNy)6(x/y>1)(0.16%C);18Mn18Cr0.72N钢凝固模式为A模式,晶界处存在少量颗粒状Cr2N相.在固溶时效态,实验钢仅析出片层状的Cr2N0.39C0.61相.随C+N含量增加,片层状析出相体积分数和片层间隙增加,析出孕育时间减少.
The effects of C and N contents on the precipitation characteristics and formation mechanism of as-cast and aged 18Mn18Cr high nitrogen steel were studied by means of metallographic microscope, scanning electron microscopy, electron probe microanalysis, transmission electron microscopy and thermodynamic calculation software. , With the mass ratio of C / N decreasing, the precipitation phases are Cr23C6 phase, σ phase and Cr2N phase, respectively.The increase of C or N content can promote the precipitation of Cr23C6 phase and Cr2N phase, respectively.C and N content affect the solidification mode of experimental steel and unstable iron The eutectoid decomposition products of 18Mn18Cr0.44N steel were AF mode. The eutectoid decomposition reaction of unstable ferrite phase was δ → σ + γ2 (0.025% C) and δ → γ2 + Cr23 (CxNy) 6 ( x / y> 1) (0.16% C). The solidification mode of 18Mn18Cr0.72N steel is mode A, and a small amount of granular Cr2N phase exists in the grain boundary.In the solid solution aging state, only laminar Cr2N0.39C0 is precipitated in the experimental steel. 61. With the increase of C + N content, the lamellar precipitated phase volume fraction and lamellar space increased, precipitation incubation time decreased.