中文摘要：

采用Themo—Calc热力学计算软件，对R5系泊链钢在400-1600℃存在的平衡析出相进行了热力学计算，并讨论了合金元素对平衡析出相的影响．结果表明，R5系泊链钢中平衡析出相主要为M23C6、M6C、MX和／kiN，其中M为Cr、Fe、Mn、Mo、Nb、Ni和V等，X为C、N和空位Va等．在此基础上讨论了合金元素C、Cr、Mo和Nb对M23C6相、M6C相及MX相的平衡摩尔含量和平衡析出温度的影响，优化了新型R5系泊链钢的合金体系及热处理工艺，提出新型R5系泊链钢的最佳热处理工艺为920±30℃淬火和600±30℃回火，其中金属元素Mo的质量分数以0．45％为佳．

英文摘要：

Equilibrium precipitated phases in R5 offshore mooring chain steel in the temperature range of 400 to 1 600 ℃ were calculated using thermodynamic software Thermo-Calc. The effects of alloying elements on these equilibrium precipitated phases were studied. The results show that main equilibrium precipitated phases in R5 offshore mooring chain steel at temperatures of 400 to 1 600℃ are M23C6, M6C, MX and/kiN, where M represents Cr, Fe, Mn, Mo, Nb, Ni and V, and X is C, N and vacancy. On this basis the influences of alloying elements C, Cr, Mo and Nb on the equilibrium mole fraction and initial precipitated temperature of M23C6, MrC and MX phases were discussed. The composition system and heat treatment condition of new R5 offshore mooring chain steel were optimized. The optimized heat treatment process is quenching at 920 ±30 ℃ and tempering at 600 ± 30℃, and the optimum content of metal element Mo is 4.3 %.