Training Online Engineering if (document.getElementById("tester") != undefined) | Feedback | Advertising Excel App. Engineering News Engineering Book Store // -->, GD&T Training Geometric Dimensioning Tolerancing. Such components are characterised by their high surface hardness combined with a very tough core (since low-carbon content)! With case hardening, low-carbon steels are first enriched with carbon in the surface layer (carburisation) and then quenched! ulepszania). Tempering is carried out at temperatures of about 150-200 ℃. 60-65 Rc hardness in carbon product and 50-55 Rc in 440C stainless steel. Case-hardening is usually done after the part has been formed into its final shape, but can also be done … This property of carbon steel can be beneficial, because it gives the surface good wear characteristics but leaves the core tough. // --> Engineering Calculators Tempering is generally employed for a partial stress relief and improves resistance to cracking from grinding operations. else GD&T Training Geometric Dimensioning Tolerancing Chromium steels such as 15H, 17Cr3, 20H, or 28Cr4 also exhibit the same low parameters. ; A group of structural steel alloys for heat-chemical treatment, which after carburizing or cyaniding, and heat treatment are expected to obtain a hard and wear-resistant abrasive surface of the product while maintaining sufficiently high core ductility. The hardness and abrasion-resistant surface is obtained by saturating it with carbon to a depth of 0.8 - 1.5mm and heat treatment, which is followed by hardening and tempering. Home document.write(''); Turning inserts and grades for hardened steel. Among the aforementioned, in the environment exposed additionally to strong and variable overloads, and strikes, where the highest strength and ductility of the core is required, chromium-nickel grades are additionally supplemented by addition of tungsten or molybdenum as in 15HN, 12HN3A, 12H2N4A , 18H2N2, 20HN3A, 20H2N4A, 18H2N4WA, 26NiCrMo14-6, 1.6958 or 18H2N4MA. Generally, it is not necessary to normalize the carbon grades for fulfilling either dimensional or machinability requirements of parts made from the steel grades listed in the table, although where dimension is of vital importance normalizing temperatures of at least 50ºF above the carburizing temperatures are sometimes required. 20Cr4 - 1.7027 - AISI 5120 - Chromium steel. In addition to chromium, elements that improve and prevent degradation of properties are added, such as Titanium - Ti, Vanadium - V, Tungsten - W, and Boron - B. Chromium, nickel and manganese increase the toughness of the steel and the ductility of the core. The carburization process depending on the grade of steel is carried out in the temperature range of about 880 - 1050 ℃.