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研究了650℃时效1—1000h对Cr21 Ni6Mn9N钢组织和氢脆敏感性的影响。结果表明,时效过程中,晶界上析出M_3C_6型碳化物,晶界附近出现贫Cr区。随时效时间的延长,碳化物变大并相互连接。晶界附近的贫Cr程度则随时效时间的延长逐渐加剧,但在100h以后又趋于恢复,当时效达1000h时恢复到与时效1—2h的试样相近。钢的氢脆敏感性随时效时间的增加而提高,并不因贫Cr现象的减轻而下降。这表明晶界碳化物的出现是时效过程中钢的氢脆敏感性提高的主要原因。
The effect of aging at 1000 ℃ for 1h to 1000h on the microstructure and hydrogen embrittlement susceptibility of Cr21Ni6Mn9N steel was studied. The results show that during the aging process, M_3C_6 carbides are precipitated on the grain boundaries, and the Cr depletion zone appears near the grain boundaries. With the aging time, carbides become larger and connected to each other. The Cr level near the grain boundary gradually increases with the extension of the aging time, but tends to recover after 100 hours. When the aging reaches 1000 hours, the sample returns to the age of 1-2 hours. The hydrogen embrittlement susceptibility of steel increases with the aging time, and does not decrease due to the reduction of lean Cr. This indicates that the occurrence of grain boundary carbides is the main reason for the increased susceptibility to hydrogen embrittlement of steel during aging.