A nozzle for gas-shielded arc welding, having a support ring (4) engaged with a welding torch (2), a cylindrical nozzle member (6) engaging a support ring (4), and a means (8) for fixing the nozzle member (6) to the support ring (4). The nozzle member (6) is made of a heat-resisting non-conductive material, and spatter is rarely deposited on the nozzle member (6). The nozzle member (6) is formed so that it can be fixed under pressure to the support ring (4), and this member can be manufactured easily. This nozzle can be used effectively, especially, as a nozzle for carbon dioxide arc welding.

Nozzle for gas-shielded arc welding

A high-quality bearing steel contains 0.70 to 1.10% by weight of C, 0.15 to 1.60% by weight of Si, 0.15 to 1.15% by weight of Mn, 0.010% by weight or less of P, 0.002% by weight or less of S, 0.50 to 1.60% by weight of Cr, 0.015% by weight or less of Al, 0.0050% by weight or less of N, 0.0006% by weight or less of O, 0.0015% by weight or less of Ti, and the remainder of Fe together with impurities. The steel can further contain 0.05 to 0.50% by weight of Mo or a member or members selected from a group consisting of 0.05 to 0.30% by weight of V and 0.05 to 0.30% by weight of Nb. the bearing steel has an excellent durability life and cold workability.

Bearing steel and method of manufacturing the same

It is an object of the invention to provide a solid railway wheel and a method of manufacturing the wheel which satisfies both of wear resistance and heat-crack resistance good for use in a high-speed railway vehicle. In the wheel of the invention, the chemical composition of a base steel comprises: 0.4% to 0.75%C; 0.4% to 0.95%Si; 0.6% to 1.2%Mn; and less than 0.2%Cr. Especially, the content of Cr is preferably 0.05% to less than 0.2% and more preferably 0.07% to less than 0.15%. It is characterized in that the wheel has pearlitic structure in a region of at least 50 mm in depth from the tread surface of the wheel. Since the relatively high Si content and the relatively low Cr content are combined, the base steel has proper hardenability as a steel for a wheel. Therefore, the stable pearlitic structure, in which hardness is high and uniform and structure does not change even when heat is generated by application of the brakes, can be formed in a wide region such as a region from the tread surface to a depth of 50 mm or deeper. The method of manufacturing the wheel of the invention is characterized by combination of the chemical composition of the base steel and a quenching process to the tread portion of the wheel. That is, when the tread of the wheel made of the steel of the above chemical composition is quenched, for example, the following cooling process is used. An operation to interrupt or weaken a cooling operation is performed at a stage before the temperature of the tread of the wheel drops to a pearlitic transformation start temperature in a continuous cooling transformation curve diagram. Thus, the pearlitic structure can be obtained without causing martensitic or bainitic transformation. The wheel having the pearlitic structure can be stably manufactured with good productivity in a commercial scale.

Railway wheel and manufacturing method of the railway wheel

There is provided steel for wheel having a chemical composition consisting of, by mass percent, C: 0.65 to 0.84%, Si: 0.02 to 1.00%, Mn: 0.50 to 1.90%, Cr: 0.02 to 0.50%, V: 0.02 to 0.20%, and S: 0.04% or less, in which 34 ≤ 2.7 + 29.5 × C + 2.9 × Si + 6.9 × Mn + 10.8 × Cr + 30.3 × Mo + 44.3 × V ≤ 43, and 0.76 × exp (0.05 × C) × exp (1.35 × Si) × exp (0.38 × Mn) × exp (0.77 × Cr) × exp (3.0 × Mo) × exp (4.6 × V) ≤ 25, the balance being Fe and impurities, and the impurities containing P: 0.05% or less, Cu: 0.20% or less, and Ni: 0.20% or less. This steel for wheel is excellent in balance between the wear resistance, rolling contact fatigue resistance and the spalling resistance, and can give a long life to the wheel.

Steel for wheel

PURPOSE: To produce a steel material for machine structure of superior toughness without performing any heat treatment by hot-working steel contg. specific range of amts. of C, Si, Mn, N and a limited amt. or below of V or Nb. CONSTITUTION: Steel contg. 0.30W0.60% C, 0.10W2.0% Si, 0.20W1.70% Mn, 0.005W0.020% N, and ≥1 kind of ≤0.50% V, and ≤0.50% Nb, and consisting substantially of the balance Fe is heated to ≥950°C, after which its hot working is started and the hot working is executed in such a way that its end temp. is below 800°C; thereafter, it is cooled at 1W100°C/min rates, whereby structural steel is obtained. The respective elements mentioned above are added at the amts. limited for the purpose of assuring strength and for deoxidation effect. The high strength is achieved by adding ≥1 kind of ≤3.50 Ni, ≤2.0% Cr, and ≤0.70% Mo in addn. to the above, and it is possible to include some amts. of Cu, Pb, etc. in order to improve weather resistance and machineability. COPYRIGHT: (C)1982,JPO&Japio

Production of structural steel

PURPOSE: Raw material steel for forging is added with V, and after forging the products are subjected to a specificaly adjusted cooling, thereby producing high- strength, high-toughness forged steel products without using refining process. CONSTITUTION: Forging steel includes, C: 0.30 to 0.60%, Si<0.50%, Mn: 0.60 to 2.0%, V: 0.30 to 0.20%, sol Al: 0.02 to 0.06%, N: 0.008 to 0.02%, and if required Cr<0.50% or one or more of specific amount of S, Pb, Bi, Te, Se, Ce, and Ca, Mn%/C% being adjusted to more than 2. The steel material is, immediately after hot forging, adjustably cooled to a temperature just above the A 3 , at a cooling rate of 0.7 to 15°C/sec. After starting modification, the material is cooled to 500°C at a rate of 0.2 to 15°. Such cooling process hinders the growing of austenite granules, precipitating V carbide and V nitride in modifying period, which function as nucleus for ferrite modification to produce very fine structure of ferrite plus pearlite, thereby providing high-strength, toughness, and malleability to as-forged products without using refining process. COPYRIGHT: (C)1979,JPO&Japio

Production of nonrefined forged steel products

PURPOSE:To perfectly spherodize metal carbides in the structure of a high carbon Cr-Mo bearing steel by repeatedly annealing the steel under specific conditions CONSTITUTION:A high carbon Cr-Mo steel contg C; 080-120%, Si; 010-080%, Mn<20%, Cr; 1-2% and Mo; 01-10% is refined in a high frequency furnace or the like and cast into an ingot The ingot is forged and drawn to a bearing round bar of uniform pearlite structure The bar is then heated to a temp from the Acid point (742 degC of the steel to the Acie point (776 degC), held for about 1hr, slowly cooled from the Arib point (710 degC) to the Arie point (660 degC) at a very slow cooling rate of 10 degC/hr, and held at 650 degC for 1hr The annealing is repeated 4 times or more By the treatment metal carbides in the structure are spheroidized and become few spherical carbides of large diameter, and hence the wear resistance and hardenability of the bearing steel are enhanced

Spheroidizing heat treatment method for high carbon- chromium-molybdenum bearing steel

PURPOSE:To enhance the wear resistance and cracking loss resistance of the titled steel and to make the steel suitable for a railroad wheel in a nonrefined state by preparing a high carbon steel contg. Si, Mn, Cr and a very small amount of Nb and/or V. CONSTITUTION:This steel for a railroad wheel has a composition consisting of 0.60-0.80% C, 0.4-1.00% Si, 0.6-1.0% Mn, 0.15-0.80% Cr, 0.03-0.15% in total of V and/or Nb, and the balance essentially Fe. This steel is rolled into a wheel and used as rolled without carrying out heat treatment.

Steel for railroad wheel with superior wear resistance

PURPOSE:To obtain steel with enhanced wear resistance and superior cracking loss resistance by specifying the composition of a steel for a railroad wheel used after hardening and tempering the tread. CONSTITUTION:This steel consists of 0.55-0.80% C, 0.40-1.20% Si, 0.60-1.20% Mn, 0.20-0.70% Cr and the balance essentially Fe. This steel has high strength (hardness, yield strength, tensile strength and fatigue strength) and is remarkably superior to an in-use steel in wear resistance. In addition, it has rather increased toughness and ductility (elongation, reduction of area, impact value and rupture toughness) and is superior to the in-use steel in cracking loss resistance. The lower limit of C is decided with respect to the wear resistance and strength, and more than the upper limit of C deteriorates the heat check resistance. The lower limit of Si is decided with respect to the wear resistance, and more than the upper limit of Si reduces the toughness. The lower limit of Mn is decided to prevent embrittlement due to S and to enhance the strength and toughness, and the upper limit of Mn is decided to enhance the hardenability and to prevent the formation of a structure other than pearlite. The lower limit of Cr is decided to strengthen the pearlite structure and to enhance the wear resistance, and the upper limit of Cr is decided to prevent the formation of a structure other than pearlite and the reduction of the toughness.

Kazuo Nakase

Papers

Production of nonrefined forged steel products

Spheroidizing heat treatment method for high carbon- chromium-molybdenum bearing steel

Steel for railroad wheel with superior wear resistance

Steel for railroad wheel with superior wear resistance and cracking loss resistance