Experimental and Analytical Study of CBN Grinding of Welded Martensitic Aging Steel.

Abstract

Martensitic aging steels (Marging steels—MS) are high-alloyed low-carbon (0.03% C) structural steels based on the Fe–Ni and Fe–Cr–Ni systems, additionally doped with cobalt, molybdenumtitaniumetc. The article presents the results of studying of the grinding process of martensitic aging steels. The physical nature of the transformations occurring in the surface layer of the grinded surface under the influence of the contact grinding temperature is considered. The steels are heated for hardening up to temperatures approximately 1200 °C. At this temperature, the intermetallic compounds of the alloying elements (usually fine and solid) dissolve in the solid solution. With rapid cooling at rates above the critical hardening rates, a decarburized “soft” martensite is formed, in which the intermetallic compounds are dissolved. This is followed by aging at temperatures of about 480–520 °C. Under the effect of tempering temperature, the precipitation hardening of steel occurs, which consists in the fact that intermetallic compounds in a finely dispersed state are separated from a solid solution and block dislocation movement, because of which the steel acquires high mechanical properties. Under the action of contact grinding temperature 550–600 °C these properties can be lost. The dependence of the contact temperature on the modes of borazon grinding is shown. The research is aimed at creating a database of permissible grinding conditions, the use of which provides optimal contact temperatures and a defect-free surface layer.