The isothermal tempering embrittlement test of 2. 25Cr-lMo alloy steel (% ： 0. 15C

2. 32Cr

0. 95Mo

0. 011S

0. 009P

0. 006 8As

0. 003 5Sb

0. 007 9Sn

0. 01V) for hydrogenation reactor with 146. 7 MPa applied stress at 468 ℃ for 125 h and 400 h has been carried out. Based on the relation curves of temperature and impact energy of hydrogenation reactor parent metal sample at 3 kinds of status - de-embrittling

embrittling and applied stress

the temper embritdement transition temperature VTr54.2(℃) value at each status and temper embrittlement damage ΔVTr54.2(℃) were obtained. The results showed that temperature and isothermal time were main factors led to material embrittlement while the influence of applied stress on temper embrittlement of 2. 25Cr-1Mo steel was not obvious.