The shaft is the same dimensions as example 1 (30 x 500 mm). desired case hardness (Fig. The total case depth is the true depth of the case. Case depth measurements are important for quality control of surface-hardened steel parts and the heat treating process. In addition, by hardening too deep, the residual surface compressive stress may be reduced. Case-Depth and Concentration-Gradient for Carbonitriding of Steels: The case-depth depends on the type of steel, the temperature and time of carbonitriding as illustrated in Fig. This Case Hardening process will be applied to the final shaped machine components. It should be recognized that the relationship between case depths as determined by the different methods can vary extensively. 19,000 Pound double helical pinion shaft carburized to an effective case depth of 0.250" being quenched into 20,000 gallons of agitated, warm oil. The standard method of determining case depth is the micro- Pinion was heat treated vertically one of two Metlab 54" diameter by 180" deep pit furnaces. As John said the parts will grow by a few thousandths. Like case hardening, nitriding is one of the thermochemical diffusion treatment processes. There are several methods of case hardening for gears, including vacuum carburizing, atmosphere carburizing, and induction hardening. where the diffusivity constant, K, depends on temperature, the chemical composition of the steel, and the concentration gradient of a given hardening species. Although case Case hardening processes harden only the exterior of the steel part, creating a hard, wear resistant skin (the "case") but preserving a tough and ductile interior. In every instant, the chemical composition or mechanical properties, or both, are changed by the process. Alloy steels are normally case hardened to increase the metal characteristics. ADVERTISEMENTS: Case and surface-hardening methods such as carburising, nitriding, carbonitriding, cyaniding, induction and flame- hardening, result in a ‘depth of case’ which is substantially harder than the inside section of the component called the ‘core’. The depth of diffusion exhibits time-temperature dependence such that: Case depth ⃜ K vTime. Engineering Materials Applications & Design. The case-hardening depth is approximately 2 mm and the hardness is 57-62 HRC by single-shot hardening. 8620 is a low nickel - chromium - molybdenum medium hardenability, case hardening (carburizing) steel, generally supplied in the as rolled condition with a maximum brinell hardness of 280 (Rc30).Characterised by good core strength and toughness in small to medium sections with case hardness up to Rc62 when carburized, hardened and tempered.8620 can also be used (uncarburised) … Case Hardening is commonly carried out under controlled atmosphere sealed quench furnaces to medium carbon steels. Gear measures 12' in diameter by 12' tall and weighs approximately 24,000 pounds. 2), case depth (Fig. An accurate method to For highly alloyed case-hardening steels, the carbon content for 550 HV is typically in the range of 0.25-0.30%. 1.) Case Hardening On low carbon steel parts (1213, 12L14, 1117, 8620, etc.) Case hardening is a heat treatment technique in which the steel surface is processed by the addition of carbon. : Carburizing: Pack, salt or gas carburize at 900 o C - 950 o C, holding for sufficient time to develop the required case depth and carbon content, followed by a suitable hardening and tempering cycle to optimise case and core properties. Heat Treatment: Annealing: Heat to 830 o C - 850 o C, hold until temperature is uniform throughout the section and cool in furnace. Case hardening a gearbox components creates a hard outer-shell and a pliable inner layer. Case hardening is specified by hardness and case depth. *For modified grades of 52100 and work roll materials, please contact us at 1.800.245.5084 or 724.452.8750. Effective case depth (ECD) and total case depth (TCD) Effective Case Depth (ECD) Effective case depth or ECD is the perpendicular distance from the surface of a hardened case to the deepest point at which a specified level of hardness is maintained. 3. 1117 case hardens to a depth or .045" at 8 hours of carburizing at 1700 deg F. Back off to 4 hours and see what happens. The measured case depth may then be reported as either effective or total case depth on hardened specimens, and as total case depth on unhardened specimens. Case hardening will not work well with the thin section material described. 8.54, based on industrial data. case depth CaII meet the load capacity requirement for the actu-al application without reaching the maximum load capacity and can thereby decrease di tortion by hardening and reduce the need.for grinding. (In some cases, the depth to the hardness value There are fundamental differences between the two processes. Large gear for an industrial application nitrided to a 0.040" case depth. This is the optimum case depth. The most widely used alloy case-hardening steel, which may be carburized and hardened to produce a hard wear resistant case combined with core strength of the order of 125,000 psi (862 N/mm2). 3), the desired case profile, and cost. The depth follows a curve but is fairly proportional accordiing to time. The case depth can be specified in two ways: total case depth or effective case depth. Depth of 23 % and a pliable inner layer nitrided to a depth... 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