硼和钒添加对Cr-Mo低合金钢步冷脆化倾向的影响

Effect of Boron and Vanadium on Step Cooling Embrittlement Tendency of 2.25Cr1Mo Steel for Fast Reactor Evaporator

2.25Cr1Mo钢是我国四代先进钠冷快堆热交换器主体结构材料,因长期在中温环境服役,第二类回火脆性是其主要失效形式之一,因此掌握关键合金元素对该类钢种的第二类回火脆性影响是实现其铸件或变形部件国产化制造的关键环节。作者采用真空感应炉、450型双辊可逆轧机制备添加B、V的2.25Cr1Mo钢板,采用步冷处理试验方法研究了B、V添加对钢的第二类回火脆性倾向的影响。结果表明:P含量为0.05 wt.%~0.06 wt.%时,2.25Cr1Mo钢的第二类回火脆性倾向大,回火脆性程度敏感系数为达174℃。0.0048 wt.%B添加条件下,钢的回火脆性程度敏感系数为166.9℃,回火脆性倾向并未得到明显改善。0.46 wt.%V添加条件下,2.25Cr1Mo钢的热处理态冲击韧性和第二类回火脆性倾向均得到一定程度的改善,其中回火脆性程度敏感系数为134℃,较未添加试验钢降低幅度为23%。

2.25Cr1Mo steel is the main structural material of the fourth-generation advanced sodium cooled fast reactor heat exchanger in China.In this moderate temperature service environment,it is very susceptive to the secondary tempering brittleness to cause component failure.Therefore,mastering the functions of the key alloy elements in steel is important to realize the domestic manufacturing of casting and wrought components.The 2.25Cr1Mo steel plates containing B and V were refined with vacuum induction furnace and rolled with double-stick reversible rolling mill,and the effect of these two alloy elements on the second kind of temper brittleness tendency was studied by step cooling test.It showed that,the second type temper brittleness tendency of 2.25Cr1Mo steel is large,and the sensitivity coefficient of temper brittleness is 174℃when P content is 0.05wt.%-0.06 wt.%.Under the condition of 0.0048 wt.%B addition,the sensitivity coefficient of temper brittleness of steel is 166.9℃,and the temper brittleness tendency has not been significantly improved.While both the impact toughness and the second temper embrittlement tendency can be improved to a certain extent with 0.46 wt.%V addition,and the sensitivity coefficient of temper embrittlement is 134℃,which is 23%lower than that of the steel without V addition.