缓慢加热条件下2.25Cr1Mo0.25V钢晶粒细化工艺研究

Research on Grain Refinement Process of 2.25Cr1Mo0.25V Steel under Slow Heating

针对加氢容器锻件热处理后易出现粗晶、混晶问题,结合大锻件的实际生产情况,研究了缓慢加热条件下(≤15℃/h) 2. 25Cr-1Mo-0. 25V钢晶粒细化工艺,试验结果表明,初始晶粒度为1. 0级时,不同奥氏体化温度一次正火后,晶粒度为混晶,不同奥氏体化温度连续退火后,组织为铁素体+碳化物,部分铁素体和碳化物呈条状。不同奥氏体化温度正火的试样与不同奥氏体化温度退火的试样再经过一次正火处理后(正火加热速度≤15℃/h),所有试样的晶粒都得到细化和均匀化,满足技术要求,但高倍下观察,局部存在尺寸相差很小的粗晶。

Regarding to rough grain and mischcrystal issues of hydrogenation vessel forgings after heat treatment, and combining with actual production condition of heavy forgings, grain refinement process of 2.25Cr-1Mo-0.25V steel under slow heating condition （ ≤ 15℃/h） has been researched. The test results showed that when initial grain size was 1.0, the grain size belonged to mischcrystal after each normalizing with different austenitizing temperatures, while the microstructure belonged to ferrite ＋ carbide after continuous annealing with different austenitizing temperatures, and some appeared as strip. Further both normalized specimens and annealized specimens with different austenitizing temperatures turned out grain refinement and uniformization after normalizing with one more time （ normalizing heating rate ≤ 15℃/h） , which satisfied technical requirements, but rough grain with lirde difference existed at local under micro- observation.