From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Journal article describing the properties, heat treatment, and applications of different grades of steel.
| Identifier | ExFiles\Box 154a\1\ scan0007 | |
| Date | 21th October 1911 | |
| MOTOR TRACTION. OCTOBER 21ST, 1911. 351 water at the same temperature; the vertical lines on the charts, with the temperatures given in Centigrade at the top, represent the drawing, or tempering, temperatures. At each of these tempering temperatures the physical properties are shown by the intersection Fig. 2.—Chart showing the properties developed by heat-treatment of grade B .30 % carbon “Y” steel. of the lines marked with the respective property represented, and the temperature line. Any other properties may be obtained which are shown by the lines, by interpolating between the two temperatures within which it lies, and then by drawing to that temperature. The scales at the side show the tensile strength and elastic limit in lbs. per square inch, and the percentage of elongation and the reduction of area. The drawing temperatures apply only to specimens of the size given; for larger sizes and shapes they would be less, whilst for smaller sections they would be slightly greater. Thus for 1½in. rounds, the drawing temperature should be about 25° Centigrade less; whilst for a large section, such as an 8in. diameter axle with a 2in. hole drilled through lengthwise, it should be about 250° less. It is impossible to give the drawing temperature for all sizes, but with the charts as a basis a manufacturer of heat-treated materials can pick out what is best adapted to his needs. Uses of “Y” Steel. “Y” steel may be used in any place where carbon steel is employed, and it can be supplied in any grade or shape in which carbon steel is now furnished. In the natural or heat-treated condition it machines well up to a tensile strength of about 125,000 lbs. per square inch, and about 12% elongation in 2in. It is used for any purpose, from rivets and bolts up to rails and springs, and gives in every case a superior result as compared with carbon steel, whilst it may be furnished in any grade desired as regards carbon and manganese content. The three grades A, B, and C, are most widely used, and are particularly adapted to heat-treated parts of motor vehicles where severe strains and shocks are met with, and a high resistance to fatigue and alternately applied stresses is essential. Grade A.{Mr Adams} This is a mild steel, and analyses as follows: Carbon ............ .15 to .25% Manganese ............ .50 to .80% Phosphorus ............ Not over .03% Sulphur ............ Not over .04% Silicon ............ Not over .20% Nickel ............ 1.20 to 1.60% Chromium ............ .25 to .50% This grade is particularly adapted to case-hardening, cold rolled sheets, cold pressed forms, seamless tubes, small drop forgings, structural shapes, bolts, high tensile rivets, or to any purpose where a mild tough steel is desired. It responds quite readily to heat treatment (see fig. 1). In the case-hardening process it takes about 25% deeper case than a carbon steel in the same time, or the same depth in less time. To secure the best results, the treatment after case-hardening should be as follows: First cool to a black heat in daylight, then reheat to 810° C. and quench in oil or water. Again re-heat to 730° C. and quench as before. This will give a fine silky core and a hard close-grained case capable of withstanding great assistance and continued wear. Grade B. This steel contains .25% to .35% of carbon, with the same percentages of manganese, phosphorus, sulphur, silicon, nickel, and chromium as contained in grade A steel. It responds quite readily to the heat treatment, giving it considerable strength with a high degree of ductility and toughness. It is principally used for automobile and carriage axles, crankshafts, driving-shafts, drop forgings, or forgings of any nature, and is, in fact, an all-round steel, being the most widely used grade. The properties developed by heat treatment of this steel are shown by the chart given in fig. 2. Grade C. This steel is in the higher carbons, and may be used for a heavier class of work. It contains .35% to .45% of carbon, and the same percentages of manganese, phosphorus, sulphur, silicon, nickel, and chromium as in grades A and B. It is largely used for heavy motor vehicle axles, locomotive driving and car axles, forgings requiring great strength, such as connecting rods, piston rods, heavy crankshafts, driving-shafts, motor vehicle steering knuckles, or other parts which are subsequently heat-treated, oil and water tempered automobile transmission gears, other gears and pinions, and for all purposes of a similar nature. The chart given in fig. 3 shows the properties developed by heat treatment for the .40% carbon steel. By varying the carbon and manganese, any grade desired may be obtained. Thus with .90% to 1.05% carbon and about .40% manganese, a superior spring steel is obtained, having a higher elastic limit and a greater resistance to fatigue and shock than a carbon steel of the same grade. In the heat-treated condition this steel shows properties far superior to those which can be obtained from carbon steels, and approximates those of the high grade 3½% nickel steels. “Y” steel can be supplied in square or round merchant bars, or in 4in. by 4in. billets. It may be described as a natural alloy steel, and is stated to be beyond question vastly superior to steel made with the alloys injected into it. Fig. 3.—Chart showing the properties developed by heat-treatment of grade C .40 % carbon “Y” steel. | ||