PURPOSE: To provide a case hardening steel consisting of specified amounts of C, Si, Mn, Ni and Mo and the balance Fe with impurities and having superior properties of preventing the formation of an abnormal surface layer during carburizing or carbonitriding CONSTITUTION: This case hardening steel consists of, by weight, 01W04% C, 002W015% Si and ≤2% Mn as essential components, 03W5% Ni and/or 005W 05% Mo and the balance Fe with impurities The steel has superior properties of preventing the formation of an abnormal surface layer during carburizing or carbonitriding, and case hardened parts having high quality and high fatigue strength can be obtd In order to improve the cold workability or to increase the strength furthermore, it is preferable to regulate the amounts of said impurities to ≤ about 0015% S, ≤ about 0015% P, ≤ about 001% N and ≤ about 0002% O COPYRIGHT: (C)1984,JPO&Japio

Case hardening steel

PURPOSE: To impart high resistance force against the formation of abnormal carburization structure to a case hardening steel by specifying the contents of C, Si, Mn, Cr, Al, and Cu in the basic components in the case hardening steel to be used for parts for structural purposes, etc. CONSTITUTION: The compsn. of the case hardening steel is specified, by weight, 0.1W0.4% C, <0.15% Si, ≤12% Mn, ≤1.5% Cr, ≤0.07% SolAl, 0.02W0.5% Cu, and the balance Fe and unavoidable impurities. If necessary, ≥1 kinds among ≤5.0% Ni, ≤2.5% Mo and ≤0.005% B and ≥1 kinds of ≤0.15% Nb and ≤0.15% V are incorporated therein. Since the case hardening steel having such compsn. is less forced with the abnormal carburization structure, the steel can impart a high degree of fatigue strength, rolling fatigue strength and wear resistance to parts for machine structural purposes when used under severe conditions. COPYRIGHT: (C)1988,JPO&Japio

Provided is a case hardening steel which allows effective inhibition of abnormal grain growth during carburizing treatment or the like and makes it possible to solve the problem of abnormal grain growth-induced reduction in characteristics. In the case hardening steel, a total amount of TiC, ZrC and AlN which are precipitate particles contained in 100 g of a steel material after subjecting the case hardening steel to hot rolling is 3.5×10−4 mole or less.

PURPOSE:To obtain a high strength carburizing steel for hardening for the cross pins of a driving shaft with improved fatigue strength by specifying the ratio of Ni/Cr, the amount of Cr+Mn+Ni and the ratio of sol. Al/N in a low C-Mn-Ni- Cr-Mo steel, and reducing the amount of O. CONSTITUTION:This steel is an alloy steel consisting of, by weight, 0.15-0.25% C, 0.10-0.35% Si, 0.60-1.50% Mn, 1.00-1.50% Cr, 3.50-4.50% Ni, 0.05-0.30% Mo, 0.015-0.030% sol. Al, 0.010-0.018% N, <=0.0020% O and the balance Fe with inevitable impurities while satisfying relations represented by equations 3.0<=Ni/Cr<=4.0, 5.5<=(Mn+Cr+Ni)<=7.0 and 1.1<=sol.Al/N<=2.0. The steel has high toughness and fatigue strength in spite of its high hardness, and the steel provides the most suitable performance to the cross pins of a driving shaft used under severe conditions.

High strength carburizing steel for hardening for cross pin of driving shaft

This steel material having low heat-treatment deformation comprises a machine structure steel used as components for motive power transmission such as gears or shafts used in automobiles, industrial machinery, or the like. The steel material comprising a machine structure steel containing, by mass%, 0.20-0.30% of C, 0.10-1.50% of Si, 0.10-1.20% of Mn, no greater than 0.030% of P, no greater than 0.030% of S, 1.30-2.50% of Cr, no greater than 0.30% of Cu, 0.008-0.300% of Al, no greater than 0.0030% of O, and 0.0020-0.0300% of N, the remainder comprising Fe and unavoidable impurities, has an Ms point of no greater than 460°C, a ratio (J9/J1.5) of the hardness (J9) at a distance of 9 mm from the quenched end of the steel material when measured by means of a Jominy end quenching method to the hardness (J1.5) at a distance of 1.5 mm of 0.70-0.85, and a ratio (J11/J1.5) of the hardness (J11) at a distance of 11 mm from the quenched end of the steel material to the hardness (1.5) at a distance of 1.5 mm of 0.67-0.78.

Machine structure steel material having low heat-treatment deformation

PURPOSE:To manufacture a steel material for gears which is less in heat treatment strain and of a stable property in addition to the same hardenability as the conventional ones by regulating the amounts of Al and N present in the steel material within a specifically proper range. CONSTITUTION:A steel material, containing 0.10-0.50% C, <0.50% Si, 0.30- 1.70% Mn, and at least one of <5.00% Ni, <2.00% Cr, and <1.00% Mo, together with 0.015-0.055% Al and 0.010-0.040% N, is used as a material gears. The crystal grain size of the steel material is refined by regulating Al/N ratio to 0.5-2.5, lowering the oxygen content of the steel by deoxidation with Al, and existing N together. Thus, because no strain occurs in the steel material during such heat treatments as carburizing, hardening, tempering, etc., gears having excellent shape accuracy can be easily manufactured.

Yoshimura Tsuneo

Papers

Lowwheat treated strained steel for gear