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对低碳马氏体型超高强度钢25SiMaCzNiMoV在不同工艺条件下的组织结构变化规律进行了仔细观察。透射电镜研究表明此钢淬火态具有自回火ε相,组织以位错马氏体为主,板条间有时可能具有孪晶关系;部分残留奥氏体膜与两邻接的位错马氏体间可分别遵循K-S及N-W关系;钢中除位错马氏体外,也存在一定量含有内孪晶的位错马氏体,个别地点尚见孪晶马氏体。在500℃,2h回火后的脆性状态,孪晶仍然存在,此时不仅可见到有断续碳化物在部分马氏体板条界析出,这些碳化物同时也在孪生面析出。Si的加入增加了ε的稳定性,减缓了马氏体的分解,将TME推迟到500℃左右,但残留奥氏体开始分解似在250℃,没有见到Si对其有延迟作用。
The microstructure of 25SiMaCzNiMoV low carbon martensitic ultrahigh-strength steel under different technological conditions was carefully observed. Transmission electron microscopy showed that the quenched steel possesses self-tempering ε phase, and the structure is dominated by dislocation martensite. The lath may sometimes have twinning relationship. Some residual austenite films and two adjacent dislocation martensite Between the KS and NW can be followed respectively; in addition to the dislocation martensite in steel, there is also a certain amount of dislocation martensite containing twins within the twin, martensite twinned in some places. At 500 ℃, 2h after tempering brittle state, twins still exist, this time not only to see intermittent carbides in the martensite slab boundary precipitation, these carbides also appear in the twin surface precipitation. The addition of Si increased the stability of ε, slowed the decomposition of martensite, delayed the TME to about 500 ℃, but the residual austenite began to decompose at 250 ℃, and no delayed action of Si was observed.