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This specification covers seamless stainless tubing for use in mechanical applications where corrosion-resistant or high-temperature strength is needed. The steel may be cast in ingots or may be strand cast. When steel of different grades is sequentially strand cast, identification of the resultant transition material is required. The tubes shall be made by a seamless process and by either cold working or hot working as specified. Seamless steel tubing is a tubular product made without a welded seam. It is usually manufactured by hot working steel and then cold finishing the hot-worked tubing to produce the desired shape, dimensions and properties All austenitic tubes shall be furnished in the annealed condition. An analysis of each heat of steel shall be made to determine the percentages of the elements specified. If secondary melting processes are employed, the heat analysis shall be obtained from one remelted ingot or the product of one remelted ingot of each primary melt.
Область применения1.1 This specification covers seamless stainless tubing for use in mechanical applications where corrosion-resistant or high-temperature strength is needed. The grades covered are listed in Table 1, Table 2, and Table 3.
(A) For small diameter or thin wall tubing or both, where many drawing passes are required, a maximum of 0.040 % carbon is necessary in grades MT-304L and MT-316L. Small outside diameter tubes are defined as those under a 0.500 in. [12.7 mm] outside diameter and light-wall tubes as those under a 0.049 in. [1.2 mm] average wall thickness (0.044 in. [1.1 mm] min wall thickness).(B) Iron shall be determined arithmetically by difference of 100 minus the sum of the other specified elements.(C) The range of (Al + Ti) shall be within 0.85–1.20 %. (A) MT446-2 is a lower carbon version of MT446-1, that has a lower tensile strength but improved ductility and toughness.(B) Carbon plus nitrogen = 0.025 max %. (A) Maximum, unless a range or minimum is indicated. Where ellipses (…) appear in this table, there is no requirement and analysis for the element need not be determined or reported.(B) % Cr + 3.3 X % Mo + 16X % N ≥ 40.1.2 This specification covers seamless cold-finished mechanical tubing and seamless hot-finished mechanical tubing in sizes up to 123/4 in. [325 mm] in outside nominal diameter (for round tubing) with wall thicknesses as required.
1.3 Tubes shall be furnished in one of the following shapes, as specified by the purchaser: round, square, rectangular, or special.
1.4 Optional supplementary requirements are provided and when desired, shall be stated in the order.
1.5 The values stated in inch-pound units are to be regarded as the standard. Within the text, the SI units are shown in square brackets. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other.