Abstract: Non-magnetic drilling steel is 200 series austenitic stainless steel, its high strength characteristics are obtained by strengthening deformation, without heat treatment, resulting in poor grain uniformity after hot forging, can not meet the requirements of grain size difference within level 2. The effect of heating temperature and soaking time of intermediate billet on grain uniformity of non-magnetic drilling steel was studied by means of increasing the heating process of intermediate billet before strengthening deformation of non-magnetic drilling products. The results show that when the intermediate billet is heated at 1100 ℃ for 2-6 h before strengthening deformation, the grain size and uniformity are ideal, the grain size is above grade 3, and the grade difference is within level 2. Although the heating temperature of the intermediate billet is too high, it will make the grain size more uniform, but it will lead to the trend of mutual merging of grains resulting in coarse grains, and the heating temperature is too low, nucleation and static recrystallization energy is insufficient, and the purpose of grain uniformity cannot be achieved.

Key words: steel for non-magnetic drilling tools, grain uniformity, intermediate billet heating