Process Parameter Control Of Water Quenching And Oil Cooling For Cold Work Roller

Rolling deformation process is an essential technology which has been widely applied in processing procedures of many materials. The performance of the roller has a considerable influence on rolling work quality. However, roller as the key component of the rolling mill has limited service life, since roller is often suffered from a variety of pressures, and these pressures have no regular direction and strength during operation. Roller life is determined by its surface hardness, effective quenching hardened layer depth and toughness. This paper investigate the hardness, toughness, strength and surface hardness of small size MC3 cold work roller which is mainly applied in stainless steel strip rolling. It should reach HRC60 to prevent roller invalid in working process. To meet the above properties, water quenching and oil cooling process in quenching process should be applied when cold work roller using whole hardening heat treatment process. However, the process parameters are largely depend on the anthropogenic impact, the instability of the MC3 cold work roller water quenching and oil cooling process parameter would result in the corresponding change in microstructure and properties of roller produce, coupled with damage from the parties to the pressure in production. Roller will soon be unable to work, which will lead to serious economic losses. Based on the above discussion, this study investigates the process parameters of cold work roller in water quenching and oil cooling.According to the feature of cold work roller of water quenching and oil cooling process, using scanning electron microscope(SEM), metallographic microscope, Rockwell and Vickers hardness tester and impact testing machine etc., the impact of various external and internal factors on service life of the roller is explored, by detecting the performance and organization of test blocks with the equipment. On this basis the solving scheme is put forward. At the same time, it also analyzes how the water quenching time can affect the performance of the material, and then improve the heat treatment process. The results of the study show that:(1) Hardness gradient of non normal failure rollers tend to steeper surrounding the hardened layer, and the microstructure change significantly, while hardness gradient of normal failure rollers tend to gentle, which is expectated for the heat treatment process design;(2) There is a certain proportional relationship between the proportion of dispersion carbide in materials and water quenching time, the same as the ratio of quenching formed lamellar marten site and quench hardening layer depth. In result, the hardness of steel increases, but the hardness gradient is not so obvious, and the curve of it tend to moderate;(3) With the increase of water quenching time, the impact properties of the test blocks decrease gradually, and with the increase of the distance from the surface, impact toughness of the same position downward trend is gradually increasing.After spheroidizing annealing at 870?, quenching and tempering treatment, water quenching by 210 seconds and oil cooling, and then 165 degrees tempering treatment, the surface hardness of the MC3 forging test block amounts to 61 HRC. Compared with the microstructure and properties of failure roller, test blocks obtain the excellent hardness, and also get gentle hardness gradient distribution and good core impact toughness, which proves that water quenching by 210 seconds and oil cooling is the proper heat treatment process parameters. The using requirements of cold roll stainless steel strip is reached in the study, and the theoretical basis is provided for the realization of the stability of the MC3 cold roller under the harsh and complex working conditions.