METHOD FOR HEAT TREATMENT OF TWO-LAYER CASTINGS OF HIGH-ALLOYED CAST IRON

摘要

The invention relates to ferrous metallurgy. A method for heat treatment of two-layer castings of high-alloyed cast iron with chromium content of 16-18 % comprises the heating on austenitization to temperature 920-950 ºC with rate 20-30 ºC/hour with soaking at temperature 3-6 hours and further cooling of castings on air with rate 150-200 ºC/hour to temperature 50-100 ºC, two-stage tempering at which on each stage castings are heated with rate 20-30 ºC/hour with technological isothermal soakings through each 150-200 ºC duration 2-8 hours to temperature 520-540 ºC, at which the base isothermal soaking is carried out for 6-10 hours, then castings are cooled with rate 10-20 ºC/h to temperature 190-200 ºC after first cycle of soaking and to 70 ºC after the second one. Technical result: increasing of mechanical properties of two-layer castings of cast iron providing high durability of working layer metal of high-alloyed chromium cast iron.