Method for refining surface grains of 2Cr10NiMoVNb stainless steel forgings through quenching three times

The invention proposes a method for refining surface grains of 2Cr10NiMoVNb stainless steel forgings through quenching three times. A thermal treatment quenching procedure of refining grains twice is added before final thermal treatment quenching and tempering of spare parts; the twice quenching procedure is about 100 DEG C lower than the traditional quenching procedure in temperature, so that the grains are evenly refined. According to the method, aiming at uneven fineness of the grains in 2Cr10NiMoVNb alloy forging structures, the quenching collocation of combining middle temperature (about 150-250 DEG C over the austenite transformation temperature), low temperature (about 100-200 DEG C over the austenite transformation temperature), and high temperature (about 300 DEG C over the austenite transformation temperature) is adopted, so that the forgings are repeatedly subjected to austenite-martensite transformation, the large grains are gradually refined in the transformation process, and finally, the alloy s