Abstract: PURPOSE:To manufacture the titled tough parts having a uniform bainite structure by heating spherical graphite cast iron having an Ms point lowered by regulating the composition, quenching the cast iron, and austempering it CONSTITUTION:Spheroidal graphite cast iron consisting of, by weight, 30-40% C, 20-40% Si, 002-01% Mg, 05-20% Mn, at least one of 05-30% Ni and 03-20% Cu, and the balance essentially Fe is cast and worked to form spheroidal graphite cast iron parts The parts are heated at 830-1,000 degC for <=5hr and quenched to 170-210 degC Since the Ms point of the cast iron is low, the austenitized matrix is not transformed into a matrix having a martensite structure by the quenching The parts are then austempered by holding at 220-420 degC for <=5min and air-cooled

Abstract: PURPOSE: To provide the titled spheroidal graphite cast iron having improved wear resistance in addition to strength and toughness by adding slightly an adequate amt. of ≥1 kind among Zr, V, Ti, W, B and Nb to the specifically composed basic component consisting of C, Si, Mn, Mg and Fe. CONSTITUTION: At least ≥1 kind among 0.05W1.0% Zr, 0.05W0.3% V, 0.05W 0.3% Ti, 0.01W0.3% W, 0.002W0.015% B and 0.04W0.3% Nb are added to the basic component consisting of 3.0W4.5wt% C, 1.5W3.0% Si, 0.2W1.0% Mn, 0.02W 0.10% Mg and the balance substantially Fe, by which a spheroidal graphite cast iron for austempering having improved wear resistance in addition to strength and toughness is obtd. The Zr, V, Ti, W, B, Nb, etc. added to the spheroidal graphite cast iron are dispersed and precipitated as carbide and carbonitride by austempering and these fine and hard particles are held by the matrix having high strength and high toughness, by which the wear resistance of the above- mentioned cast iron is improved. COPYRIGHT: (C)1985,JPO&Japio

Abstract: PURPOSE: To reduce the Mo and Ni contents of spheroidal graphite cast iron without deteriorating the heat treatability, to enable normal austempering, and to reduce the production of a strain by regulating the amounts of Mn and Cu in the cast iron to proper values. CONSTITUTION: Spheroidal graphite cast iron consisting of, by weight, 3W4% C, 1.5W3% Si, 0.3W0.8% Mn, 0.3W2% Cu, 0.005W0.2% graphite spheroidizing agent and the balance Fe is cooled from a temp. at which austenite is stable to the bainite forming temp. at a cooling rate at which no pearlite structure is precipitated. Though little Mo and Ni are contained as mentioned above, extremely superior spheroidal graphite cast iron for austempering is obtd. The cast iron is especially suitable for use as the material of thick-walled parts to be austempered, and when the cast iron is subjected to austempering by making use of upper bainite or to austempering followed by air cooling, a high strength product can be obtd. at a low cost. COPYRIGHT: (C)1985,JPO&Japio

Abstract: PURPOSE: To obtain the titled cast iron having superior mechanical properties and corrosion resistance by austempering high Si spheroidal graphite cast iron having a specified composition contg. C, Si, Mn and Mg to form a bainite structure contg. a large amount of a retained austenite structure. CONSTITUTION: High Si spheroidal graphite cast iron consisting of, by weight, 3.0W4.5% C, 3.0W5.5% Si, 0.2W1.0% Mn, 0.02W0.10% Mg and the balance essentially Fe is austempered to adjust the amount of a retained austenite structure in the matrix to 30W80vol% and the amount of a bainite structure 70W 20vol%. High Si spheroidal graphite bainite cast iron having superior mechanical properties such as hardness, tensile strength, yield strength and elongation and superior corrosion resistance is obtd. COPYRIGHT: (C)1985,JPO&Japio

Abstract: Hardened surface camshafts are cast from an alloyed flake graphite iron and subjected to an austenitising treatment followed by an interrupted quench and austempering The alloy content of the iron is low and the composition range given is:- Carbon 30% to 36% Silicon 175% to 26% Manganese 05% to 09% Chromium 01% to 04% Tin 01% maximum Sulphur 01% maximum Phosphorus 02% maximum Iron & the balance Impurities Other alloying elements of Copper, Titanium and Molybdenum may be included The camshafts are austenitised at 850 DEG -920 DEG C, followed by austempering at 320 DEG - 400 DEG C and then air cooling to produce a structure of bainite with a significant proportion (eg 30%) of retained austenite

Abstract: PURPOSE:To obtain spherical graphite cast iron high in tenacity and tensile strength provided with easy machinability such as cutting after heat treatment, by converting the base structure of spherical graphite cast iron to a two-phase mixed structure consisting of bainite and ferrite. CONSTITUTION:Spherical graphite cast iron has a composition consisting of, on the weight basis, 1.9-2.7% C, 1.8-3.0% Si, below 0.5% Mn, 0.01-0.04% Mg and the remainder Fe and having an Si/C ratio exceeding 0.9 and comprises a two-phase mixed structure consisting of ferrite and bainite in which graphite is uniformly dispersed. This spheroidal graphite cast iron is prepared as described hereinafter. That is, a molten metal is cast according to a usual method and the obtained base material having a ledeburite structure constituted by uniformly dispersing fine graphite particles in a cast structure is used to be heated at about 900-1,000 deg.C for about 0.5-5hr in first stage heat treatment. In the next step, the heat treated base material is heated at a temp. directly below an A1 transformation point for about 0.5-5hr and, after this second stage heat treatment, heated to the coexisting temp. of the aforementioned two- phase and subjected to austempering treatment wherein the final heat treated base material is rapidly cooled to about 220-420 deg.C and held at this temp. for about 0.1-3hr to obtain the product.

Abstract: Hardened-surface camshaft castings particularly suitable for highly stressed service are manufactured from compacted graphite iron. A low alloy content and interrupted austempering treatment are used to develop a wear resistant bainitic microstructure containing retained austenite on the surface of the castings and the sections adjacent thereto. The preferred composition range of the compacted graphite iron is:- Carbon 3.2% to 3.6% Silicon 2.0% to 2.6% Manganese 0.5% to 0.9% Copper 0.15% Magnesium 0.02% to 0.04% Titanium 0.05% to 0.1% Sulphur 0.02% Phosphorus 0.05% Iron & Impurities the balance y

Abstract: PURPOSE:To perform surface hardening heat treatment for providing necessary characteristics to steel for a high load gear, etc. in a short-time heat cycle by carbonitriding the steel under specified conditions, austempering it by quenching in a hot bath, and carrying out cooling. CONSTITUTION:Steel is carbonitrided at 800-900 deg.C, austempered by quenching in a hot bath at 230-300 deg.C, and isothermally held for a time enough to transform the base part to lower bainite and not enough to cause the transformation of the surface layer. Thus, the lower bainite transformation is finished in the base part, and the surface layer becomes the state of supercooled austenite. The steel is then cooled to cause martensite transformation only in the surface layer, thereby giving high surface hardness, large surface residual compressive stress and high base hardness such as >=about 600Hv.

Abstract: PURPOSE:To subject a steel material easily to softnitiding and austempering without using any salt bath agent, by cooling the steel material quickly to a softnitriding temp. from the austenitizing temp. thereof, holding the same at said temp., and subjecting the material to austempering and softnitriding simultaneously. CONSTITUTION:Steel materials 2 are introduced with a meashed belt type conveyor 4 into a heating furnace 1 kept in a non-oxidative atmosphere where the materials are heated to the austenitizing temp. thereof, and are then charged into a powder fluidized layer 5A in a cooling tank 3. The layer 5A is constituted of powder of Al2O3, etc. and is kept fluidized by non-oxidative gases 6 introduced through a blow pipe 9 from the outside so that the materials 2 are quickly cooled from the austenitizing temp. to a softnitriding temp. and are held at said temp. The materials 2 are introduced with a meshed belt type conveyor 7 into a gas softnitriding furnace 8A, where the materials are held at a softnitriding temp. in an atmosphere of gaseous ammonia or the like. The softenitrided mateials 2 are discharged to the outside of the furnae with a meshed belt type conveyor 10.