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Aviation History
1917
1917 - 1248.PDF
If t"< MANUFACTURE.—3. («) The steel shall be manufactured, or at least finished by the open-hearth, electric furnace, or crucible process. (b) A sufficient discard shall be made from each ingot to secure freedom from piping and undue segregation. (c) The billets from which the bars are made are to be rough turned or chipped to remove all surface defects which might produce seams in the finished bar or forging. No under- cutting in chipping will be allowed. Heat Treatment.—(d) The manufacturer shall state the heat treatment recommended to give physical properties specified. (e) If the bars are delivered in the heat-treated condition, and the physical tests show that the heat treatment has not been correct, the bars may be re-treated at the option of the purchaser. WORKMANSHIP AND FINISH.—4. (a) The bars are to be sound, commercially straight, free from pipes, laps, cracks, twists, seams, voids, and damaged ends, and are to have a workmanlike finish. They are to be uniform in quality, within the stipulated margins of manufacture, capable of being turned and threaded readily and of taking a good finish. (b) Any article may be rejected because of injurious efects or faults in manufacture at any time, notwithstanding ^hat it has previously passed the physical and chemical tests ; it shall be returned to the manufacturer at the latter's expense. This clause shall not be taken to apply to materials fabri- cated after export. PHYSICAL PROPERTIES AND TESTS.—;. The bars shall have the following physical properties : Tensile Test.—(a) Minimum tensile strength, 80,000 lbs. per sq. in. (56.24 kg. per sq. mm.) ; minimum yield point 60,000 lbs. per sq. in. (42.18 kg. per sq. mm.) ; minimum elonga- tion in 2 in. (50.8 mm.) or proportional gauge length 22 per cent. ; minimum reduction of area, 45 per cent. Impact Test.—(b) In all cases in which impact testing machines of the pendulum type are available, tests may be carried out to determine the specific impact work of rup- ture in ft.-lbs. (or kilogram-metres). Results markedly lower than the average for this type of material will be sufficient cause for further investigation (or reheat treatment) of the material. SELECTION OF TEST SPECIMENS.—6. Three bars of each size rolled from a heat shaTl be taken and test pieces pre- pared in accordance with the I.A.S.B. standards. Each test piece and the bar from which it is cut shall be stamped with an identifying number. Should any of the test pieces, after being heat treated in the manner recommended by the steel manufacturer, fail to show the prescribed physical properties, new test pieces similarly identified shall be made from the same three bars. At the option of the purchaser the steel manufacturer may prescribe a different heat treat- ment for the second set of test specimens, and to that end he may make such tests as he desires from the remainder of the three bars taicen for the tests. Should any of the three specimens taken for the final tests fail to show the required physical properties, the bars of that heat of the size repre- sented by the specimens shall be rejected. Where bars are purchased in the heat-treated condition, test specimens shall be cut from the heat-treated bar. DIMENSIONS AND TOLERANCES.—7. The dimensions and tolerances shall be those given in the specification 3S11. DELIVERY, PACKING AND SHIPPING.—8. (a) The bars may bs delivered in the annealed or in the heat-treated condition. (b) The bars, shall, in general, be grouped in bundles weighing not more than 250 lbs. (113.4 kg.) unless otherwise agreed between manufacturer and purchaser. The heat and the I.A.S.B. steel serial numbers shall be plainly marked on a metal tag attached to each bundle. If bars are not so grouped and bundled, each bar shall be plainly marked with the heat number and the I.A.S.B. steel and serial number. 3S3—Specifications for Alloy Steel Bars and Billets.(100,000 lb. sq. in. Tensile Strength.) GENERAL.—1. The general specifications, 1G1, shall form,according to their applicability, a part of these speci- fications. f MATERIAL.-^. The material for these bars shall be chosenfrom among the I.A.S.B. standard alloy steels listed below. The composition chosen shall be stated by the manufactureror contractor, and is further limited as follows : Carbon, not over 0.35 per cent.MANUFACTURE.—3. (a) The steel shall be manufactured or at least finished by the open-hearth electric furnace orcrucible process. (b) A sufficient discard shall be made from each ingot tosecure freedom from piping and undue segregation. - NOVEMBER 29, 1917* (c) The billets from which the bars are made are to berough turned or chipped to remove all surface defects, which might produce seams in the finished bar. No undercuttingin chipping will be allowed. Heat Treatment.—[d) The steel manufacturer shall statethe heat treatment recommended to give the physical proper- ties specified.(e) If the bars are furnished in the heat treated condition and the physical tests show that the heat treatment has notbeen correct, the bars may be re-treated at the option of the purchaser. W'ORKMANSHIP AND FINISH.—4. (a) The bars are to besound, commercially straight, free from pipes, laps, cracks, twists, seams and damaged ends, and are to have a work-manlike finish. They are to be uniform in quality, within the stipulated margins of manufacture, capable of being turnedand threaded readily, and of taking a good finish. [b) Any article may be rejected because of injurious defectsor faults in manufacture at any time, notwithstanding that it has previously passed the physical and chemical tests ;it shall be returned to the manufacturer at the latter's expense. This clause shall not be taken to apply to materialsfabricated after export. PHYSICAL PROPERTIES AND TESTS.—5. (a) The bars shallhave the following physical properties : Tensile Test.— b) Minimum tensile strength, 100,000 lbs.per sq. in. (70.30 kg./mm.2); minimum yield point, 80,000 lbs. per sq. in. (56.24 kg./mm.2) ; minimum elongation in 2 in.(50.8 mm.) (or proportional gauge length), 20 per cent. ; minimum reduction of area, 50 per cent.Impact Test.— (c) When impact-testing macliines of the pendulum type are available tests shall be carried o«it ifrequired to determine the specific impact work of rupture in foot-pounds (or kilogram-metres). Results markedlylower than the average for this type of material will be sufficient cause for further investigation (or reheat treatment)of the material. Selection of Test Specimens.— d) Three bars of each sizerolled from a heat shall be taken and test pieces prepared in accordance with the I.A.S.B. standards. Each test pieceand the bar from Which it is cut shall be stamped with an identifying number. Should any of the test pieces, afterbeing heat treated in the manner recommended by the steel manufacturer, fail to show the prescribed physicalproperties, new test pieces similarly identified shall be made from the same three bars. At the option of the purchaser thesteel manufacturer may recommend a different heat treat- ment for the second set of test specimens, and to that end hemay make such tests as he desires from the remainder of the three bars taken for the tests. Should any of the three speci-mens taken for the final tests fail to show the required physical properties, the bars of that heat of the size repre-sented by the specimens shall be rejected. When bars are purchased in the heat-treated condition, test specimens shallbe cut from the heat-treated bar. DIMENSIONS AND TOLERANCES.—6. The dimensions andtolerances shall be those given in the Specification 3S11. DELIVERY, PACKING AND SHIPPING.—7. (a) The barsmay be delivered in the annealed or in the heat-treated condition.(b) The bars shall in general be grouped in bundles weighing not more than 250 lbs. (113-4 kgs.), unless otherwise agreedbetween manufacturer and purchaser. The heat number and the I.A.S.B. steel serial number shall be plainly markedon a metal tag attached to each bundle. If bars are not so grouped and bundled, each bar shall be plainly markedwith the heat number and the I.A.S.B. steel serial number. Chemical Composition of Standard Alloy Steels. NICKEL STEELS. Phos- Sul-phorus, phur, Carbon. Manganese, maxi- maxi- Nickel. Chromium.mum. mum. 0.15-0.25 0.30-0.25 0.040 0.045 3.25-3.75 0.20-0.30 0.50-0.80 0.040 0.045 3.25-3.75 .. • 0.25-0.35 0.50-0.80 0.040 0.045 3.25-3.75 NICKEL-CHROMIUM STElS.S. 0.15-1.25 0.30-0.60 0.040 0.045 1.00-1.50 0.45-0.75 0.25-0.35 0.50-0.80 0.040 0.045 1.00-1.50 0.45-0.75 0.25-0.35 0.30-0.60 0.040 0.045 1.50-2.00 0.90-1.25 0.10-0.20 0.30-0.60 0.040 0^)45 2.75-3.25 0.70-0.95 0.25-0.35 0.45-0.75 0.040 0.045 2.75-3.25 0.70-0.95 0.10-0.20 0.30-0.60 0.040 0.045 3.25-3.75 1.25-1.75 0.25-0.35 0.30-0.60 0.040 0.045 3.25-3.75 1.25-1.75 Number. 2320.. 2325 .. 2330.. 3120 3230 .. X33I5X3330 3315 • • 3330 .. 124?
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