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研究了11Cr-6Co-Mo-V-Nb—N热强钢的高温强度和550℃、600℃蠕变性能,用透射电子显微镜观察了试验前后的显微组织,与不含Co的同类钢种进行了对比。低碳含Co的12％Cr钢(S/SAV)比不含Co的12％Cr钢具有较高的室温屈服强度、高温拉伸强度和550℃短时蠕变强度。强化的主要原因是低碳含Co钢中高位错密度促使细小的M_2X相析出引起的沉淀硬化作用。随试验时间增加M_2X转变为M_(23)C_6,S/SAV钢的抗蠕变性能逐渐降低到不含Co钢的水平。其600℃抗蠕变性能低于不含Co钢的原因,可能与Co降低钢的相变温度使基体晶格不稳定有关。
The high temperature strength and creep properties at 550 ℃ and 600 ℃ of 11Cr-6Co-Mo-V-Nb-N hot-rolled steel were studied. The microstructures before and after the test were observed by transmission electron microscopy. Made a contrast. Low-carbon Co-containing 12% Cr steel (S / SAV) has higher room temperature yield strength, high temperature tensile strength and short-time creep strength at 550 ℃ than non-Co 12% Cr steel. The main reason for strengthening is the precipitation hardening effect caused by the high dislocation density in the low-carbon Co-containing steel that precipitates the fine M 2 X phase precipitation. With the increase of M_2X to M_ (23) C_6, the creep resistance of S / SAV steel gradually decreased to the level of Co-free steel. Its creep resistance at 600 ℃ is lower than that of Co-free steel, which may be related to the fact that Co reduces the phase transformation temperature of the steel and makes the matrix lattice unstable.