The paper shows that high temperature heating (from 1 100 to 1 170 0C) for the subsequent quenching of high-chromium steels of a martensitic-carbide class 95X18 and X12MFL provides structure to the metal base, which consist of high-carbon containing martensite and residual metastable austenite with some carbides. The resulting structure has a high capacity for frictional hardening. Experiments with cold processing treatment of the analyzed steels also showed that after high-temperature quenching with subsequent cooling to -70 0C, sufficient cooling martensite is formed, which in combination with residual metastable austenite, provides an increase of abrasive wear resistance by 25 % compared to high temperature annealing.
Quality, reliability, and service durability of mill rolls are critical factors determining the quality of finished products and efficiency of rolling mills. The main problem that arises in the course of production of steel forged mill rolls is selection of reasonable conditions of heat treatment. As far as the size of the grain with an original structure and the pattern of distribution of separate structural components within the billet play a significant role in formation of final properties of the article, the objectives of this work are studying the heat treatment influence on the microstructure and hardness of steel mill rolls and development of reasonable process conditions on the basis of obtained data, in particular: determining the optimum conditions of primary heat treating the cold rolling mill rolls after their forging to reach the homogeneous structure and reduce the carbide grid score and carbide liquation; determining the optimum conditions of secondary thermal treatment of cold rolling mill rolls to provide the hardness within the range of about 300 HB, favorable structure for industrial frequency current hardening and reduction of carbide network score and carbide liquation; determining the hardening temperature, holding time and cooling rate to obtain the optimum structure and hardness within the range of 650-700 HB. Optimization of heat treatment conditions and analysis of steel microstructure have been performed with the application of cylindrical items (diameter 30 mm, height 20 mm) cut from the sample and template. Based on the study findings some microscopic images of steel microstructure after application of certain heat treatment conditions have been made and data on carbide network and current grain evaluation have been obtained
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