基于步冷试验的2.25Cr-1Mo-0.25V钢母材及焊缝回火脆化研究

对原始态、步冷态、脱脆态和脱脆步冷态2.25Cr-1Mo-0.25V钢母材及焊缝冲击试验结果进行分析,得到了母材和焊缝在不同状态下的韧脆转变温度vTr54.2和FATT以及脆化度ΔvTr54.2和ΔFATT。试验结果表明,步冷试验之后,母材发生较低程度脆化或脱脆现象,但是脆化度或脱脆度较低,表明母材具有良好的抗回火脆化性能;经脱脆试验后,母材和焊缝都发生较高程度的脱脆,表明材料的脆化主要是由于回火脆化引起的,脱脆试验使得材料的韧脆转变温度降低;脱脆步冷试验后,焊缝发生较高程度的脆化,焊缝对脱脆步冷试验的敏感性较高,脱脆步冷试验有效促进了焊缝的脆化。在相同脆化条件下,母材的脆化敏感性低于焊缝,焊缝更易发生脆化。

Study on Temper Embrittlement of 2.25Cr-1Mo-0.25V Steel Base Metal and Welded Joint Based on Step-cooling Test

The ductile-brittle transition temperature v T r54.2 and FATT,as well as the degree of embrittlementΔv T r54.2 andΔFATT were obtained by analyzing CVN impact test results of 2.25Cr-1Mo-0.25V steel base metal and welded joint under the as-received state,step-cooling state,de-embrittlement state and step-cooling state after de-embrittlement.The test results show that after step-cooling test,the base metal experienced a lower degree of embrittlement or de-embrittlement,but the degree of embrittlement or de-embrittlement was relatively low,indicating that the base metal has good capability to resist temper embrittlement.After de-embrittlement test,both base metal and welded joint experienced a high degree of de-embrittlement,which shows that the embrittlement of the material was mainly caused by temper embrittlement.The de-embrittlement test reduced the ductile-brittle transition temperature of the material.After the step-cooling test,the welded joint experienced a high degree of embrittlement,and the welded joint was more sensitive to step-cooling test,which effectively promoted the embrittlement of the welded joint.Under the same embrittlement conditions,the embrittlement sensitivity of the base metal was lower than that of the welded joint,which is more susceptible to embrittlement.