回火时间对T91钢625°C持久性能及组织演变的影响

Effect of Tempering Time on Stress Rupture Properties and Microstructure Development of T91 Steels at 625(°C)

研究了不同回火时间对T91钢625°C下持久性能及形变前后组织的影响.结果表明:回火时间对T91钢625°C持久寿命的影响与施加的持久应力水平有关;低于118 MPa的应力下,回火时间较长的试样具有更高的持久性能,而在较高应力下则反之;长时间回火对Laves相在后续低应力持久过程中的析出起到促进作用,但并未对持久性能造成不利影响,其原因可能是Laves相的析出阻滞了M23C6强化相的粗化.

The effect of tempering time on T91＇s rupture life is dependent on the stress applied on the specimen. When the stress is below 118 MPa, long tempering time results in better rupture life. While under a higher stress, the situation is reversed. Long tempering time may promote the precipitation of Laves phase during low-stress rupture. However, the precipitation of Laves phase has no negative impact on rupture life. The precipitation of Laves phase might delay the coarsening of M23C6.