Change in the mechanical properties of chromium-manganese-molybdenum steel during mechanical and heat treatments

Influence of mechano-thermal treatment on behaviour of low-alloyed steels 38-40 KhGNM and 38 KhA was studied. Changes in strength and plasticity of steels were analyzed after drawing with variable strains and the following thermal treatment (2-10 hours exposure at 200 deg - 700 deg C). In order to estimate the effect of mechano-thermal treatment conditions on plasticity of low-alloyed steels, the steels were gauged in the range of deformations from 0.080 to 0.440 and annealed as follows: the steels 38KhGNM and 40 KhGNM were heated to 690 deg C, kept for 4 hours, cooled to 300 deg C in the furnace and then in air; the steel 38 KhA was recrystallized at 720 deg C and kept for 4 hours (method 1), heated to 750 deg C, kept for 2 hours, cooled to 680 deg C, kept for 2 hours and then cooled in air (method 2). In course of drawing and the following 'relaxation' the 38 KhGNM steel undergoes deformation ageing which does not affect its behaviour during further recrystallization