1、* 1. SCOPE SUPERSEDING MIL-S-6598A 10 July 1952 , MILITARY SPECIFICATION. STEEL BAR (LOW EXPANSION, FREE CUTTING, 36 PERCENT NICKEL) This specification is mandatory for use by all Depart- ments and Agencies of the Department of Defense. 1.1 Scope - This specification covers the requirements for a lo
2、w coefficient of expansion, free cutting, steel bar. 1.2 Classification - Bars shall be of the following finishes, as. specified (see 6.2). Hot finished - Scale not removed Cleaned - Pickled or blast cleaned Centerless ground - Round bars only 2. APPLICABLE DOCUMENTS 2.1 . The following documents of
3、 the .issue in effect on date of invitation for bids or request for proposal, form a part of this specification to the extent specified herein: STANDARDS ./ Federal Fed. Test Method Metal; Test Methods Std. No. 151 FED-STD-183 Continuous Identification Marking of Iron and Steel Products Military MIL
4、STD-163 Steel Mill Products, Preparation for Shipment and Storage Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MILS-16598B S. (Copies of specifications, standards, drawings, and publications required by suppliers in connection with specific procur
5、ement functions should be obtained kom the procuring activity or as directed by the contracting officer. ) * 2.2 Other publications - The following documents form a part of this specification to the extent specified herein. Unless othe.rwise indicated, the issue in effect on date of invitation for b
6、ids or request or proposal shall apply. American Society For Testing and Materials (ASTM) A 317 Macroetch Testing and Inspection of Steel Forgings E 8 Tension Testing of Metallic Materials (Application for copies should be addressed to the American Society for Testing and Materials, 1916 Race Street
7、, Philadelphia, Pennsylvania 19103. ) 3. REQUIREMENTS * 3.1 Material - The steel shall be manufactured by the crucible or the electric-furnace process. 3.1.1 Process - Unless otherwise specified, the steel bars shall be hot rolled or forged. * 3.2 Chemical composition - The chemical composition shal
8、l con- form to the composition of Table I. TABLE I CHEMICAL COMPOSITION i Carbon (max. ) (max. ) (max. ) Silicon Manganese Nickel Selenium Iron Percent Per cent Percent Percent Percent Percent .O. 15 Remainder - 1/ O. 15-0.25 35.0-36.5 O. 35 O. 50 1/ Incidental elements must not be present in such p
9、roportions as will modify the low expansivity characterisitcs, reduce the strength or add to the difficulty of machining. 3.3 Mechanical properties - The mechanical properties of the steel shall conform to the requirements of Table II. 2 Provided by IHSNot for ResaleNo reproduction or networking per
10、mitted without license from IHS-,-,-MILS-16598B 3.4 TABLE II MECHANICAL PROPERTIES Yield strength Tensile (min. ) (min. ) -of area - in 2 inches offset) strength Reduction Elongation ,(O. 2% (min. ) (min. ) psi percent percent psi 75,000 40 30 45,000 Finish - Hot finished bars shall be furnished as
11、forged or rolled. Bars specified in the cleaned finish shall be free from scale. Centerless ground bars shall be bright and free from pits, scratches, or other injurious defects (see 1.2). - * 3.5 Macrostructure - Visual examination of deep acid etched bars shall show no more than slight pitting and
12、 no evidence of change in structure from .the surface to the center (see 4.6). * 3.6 Tolerances - Variations from nominal dimensions shall be within the permissible limits shown in Tables III to VI inclusive. TABU III HOT-FINISHED BARS: ROUNDS AND EQUARES Diameter or distance across flats Inches 5/1
13、6 and less Over 5/16 to 7/16 inclusive Over 7/16 to 5/8 inclusive Over 5/8 to 7/8 inclusive Over 7/8 to 1 inclusive . Over 1 to 1-1/8 inclusive Over 1-1/8 to 1-1/4 inclusive Over 1-1/4 to 1-3/8 inclusive Over 1-3/8 to 1-1/2 inclusive Permissible variations “+r Minus O. 005 ,006 ,007 .O08 . O09 . O10
14、 . o11 .o12 .O14 -0.005 .O06 .O07 .O08 . O09 . O10 . o11 . o12 .O14 Out of round - 1/ or square Inch O. 008 . O09 . O10 .o12 .O13 .O15 .O16 ,018 .o21 0 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIGS-16598B TABLE III (Continued) Diameter or di
15、stance across flats Inches Over 1-1/2 to 2 inclusive Over 2 to Z-I/Z inclusive Over 2-1/2 to 3-1/2 inclusive Over 3-1/2 to 4-1/2 inclusive Over 4-1/2 to 5-1/2 inclusive Over 5-1/2 to 6-1/2 inclusive Over 6-1/2 to 8 inclusive Permissible variations P lus Minus Inch . Inch .O16 .O16 .O31 O .O47 o .O63
16、 .o .O78 O .125 O .156 O Out of round II/ or square Inch . .O23 .O23 .O35 b 046 .O58 .O70 . * .O85 I/ Out of round is the difference between the maximum and minimum diameters of the bar, measured at the same cross section. Out of square is the difference in the two dimensions at the same cross secti
17、on of a square bar, each dimension being the distance between opposite faces, the adjacent sides forming approximately 90- degree angles, TABLE N HOT-FINISHED BARS: HEXAGONS AND OCTAGONS Inches 1/2 and less Over 1/2 to 1 inclusive Over 1 to 1-1/2 inclusive Over 1-1/2 to 2 inclusive Over 2 to 2-1/2 i
18、nclusive Over 2-1/2 to 3-1/2 inclusive 4 /c . 1 . l- -. Permissible variations Maximum difference Plus Inch O. 007 .o10 . o21 .O31 .O47 .O63 3 measurements Minus (for hexagons only) O. 007 . O10 . o21 .O31 .O47 .O63 o. o11 .O15 .O25 .O31 .O47 .O63 Provided by IHSNot for ResaleNo reproduction or netw
19、orking permitted without license from IHS-,-,-MIL-S-16578B 95 9979706 0117023 7 MILS-1 6398B Ordered width TABLE V HOT-FmTISHED BARS:. FLATS Inches L and less Over 1 to 2 inclusive Over 2 to 4 inclusive Over 4 to 6 inclusive Over 6 to 8 inclusive Over 8 to 10 inclusive Permissible variations Width I
20、 Plus Inch 1/64 1 /32 1/16 3/32 1/8 5/32 1/8 inch to inclusive (2) .1/64 1/32 1/32 1/16 3/16 5/32 O. 008 . o12 .O15 .O15 .O16 . o21 Thickness Over 1/2-inch to inclusive (2) inclusive (?I 2 inches thick 1-inch thick Over 1 inch to Inch o. 010 Inch .O15 .O47 .O31 .O31 .O25 ,031 .o20 .O31 .o20 O. 031 T
21、AB= VI CENTERLESS-GROUND BARS: ROUNDS ONLY Permissible variations Minus Diameter Less than 1 1 to 1-1/2 exclusive 1-1/2 to 4 inclusive o. 002 .O03 .O03 ,0025 .O025 o. O02 from 3.7 Length - The bars shall be commercially straight and free twist and damaged ends (see 6.2, 6.2.1). * 3.7.1 Exact lengths
22、 - Bars may be ordered to exact lengths or in lengths expressed as a multiple of a definite unit. A tolerance of plus one eighth inch will be allowed on material so ordered. 3.7.2 Mill lengths - Unless otherwise specified, material shall be furnished in full lengths of 6 to 20 feet. Not more than 10
23、 percent of lengths shorter than 10 feet will be accepted. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-Lb598B 95 m 9999906 OLL70L4 9 I * MIL- S 165 98B 3. 8 Identification of product - Each piece shall be identified in accordance with FED-S
24、TD-183, and the markings shall include the number of the heat of metal, the manufacturers identification, .condition, and designation of this specification. * 3.8.1 Bars of the same size and smaller than 1/2 inch dianieter of- 3/8 inch width of flat shall be properly marked or tagged at each end and
25、 bundled. An extrg marking or tag shall be attached to each bundle. -. * 3.9 Workmanship - The steel bars furnished under this specification shall be uniform in quality and condition, smooth, free from pipes, laps, cracks, twists, seams, flakes, heat checks, slag hard spots, porosity, slivers, scabs
26、, rolled-in scale, fissures, gas cavities, sponginess, excessive segregation, or any other defects which due to their nature, degree, or extent will be detrimental to the performance of parts fabricated from the metal. 4. QUALITY ASSURANCE PROVISIONS * 4.1 Responsibilityfor inspection - Unless other
27、wise specified in the contract or purchase order, the supplier is responsible for the performance of all inspection requirements as specified herein. Except as otherwise specified in the contract or order, the supplier may use his own or any other facilities suitable for the performance of the inspe
28、ction requirements specified herein, unless disapproved by the Government. The Government reserves the right to perform any of the inspections set forth in the specification where such inspections are deemed necessary to assure supplies and services conform to prescribed requirements. * 4.2 . Classi
29、fication of inspection - Inspection of the steel is class- ified as quality conformance inspection (see 4.3 through.4.6.3). * 4.3 Examinations - * 4.3.1 Sampling for examination of dimensions, finish, workmanship, packaging, and identification marking - Units of prqduct shall be randomly selected sa
30、me nominal dimensions, and offered for acceptance at one time. . in accordance with Table VII to represent each lot of material of one heat, the * . 4.3.2 Exmination of preparation for delivery - Preparation for delivery shall be examined for conformance to Section 5. 4.4 Chemical analysis - Provide
31、d by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIES-16598B . TA B LE V II SAMPLING FOR EXAMINATION OF PRODUCT Lot size. Sample size .Acceptance no. 1 to 4 1 o .5 to 110 5 O 111 to 500 7 O 501 to 800 10 0- 801 to 1200 15 o Over 1200 25 O ._ * 4.4.1 Size of
32、lot - For the purpose of sampling for chemical analysis a lot shall consist of all material made from the same heat or melt of steel. If the heat or melt cannot be identified, a lot shall be limited to 500 pounds of bars of each size and configuration. * * 4.4.2 Sampling - Unless otherwise specified
33、, the sample shall repre- sent material from the topmost portion of an ingot. If unable to identify the melt, a sample shall be taken from each of two bars in the lot and analysed separately. Drillings may be taken from broken test specimens. Drillings shall be fine, clean, and free from oil, dirt,
34、grit, surface scale, or other foreign matter, and shall consist of not less than 2 ounces. 4.4.3 . Test method - Chemical analysis shall be made in accordance with Method No. 111.2 or 112.2 of Fed. Test Method Std. No. 151 on samples selected as specified in 4.4.2 to determine compliance with 3.2. I
35、n the event of disputes, the analysis of Method No. 111.2 shall be the basis for acceptance or rejection. 4.5 Tensile test - 4.5.1 Size of lot - For the purpose of sampling for mechanical tests a lot shall consist of all bars of the same size produced from the same heat or melt of steel and offered
36、for delivery at the same time. If the heat or melt cannot be identified, a lot shalI be limited to 500 pounds of bars of each size and configuration. 4.5.2 Sampling - Not less than 2 bars nor more than 2 percent of the bars in each lot shall be selected or tension test specimens. From each bar selec
37、ted a single tension test specimen shall be prepared. Extra length shall be provided on bars from which test specimens are to be taken. Material shall be provided for possible extra tests. The test specimens should be located in that part of the bar nearest the uppermost part of the ingot as cast, u
38、nless otherwise specified. 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MILS-16598B * 4.5.3 Test method - The tensile test shall be performed in accordance with ASTM Method E 8 on samples selected.as specified in 4.5.2 to determine compliance wi
39、th 3.3. Wherever practicable , bars shall be tested in full size, the cross section of the specimen being the full cross section of the material. If full size specimens are not practicable, the Standard O. 500 in. (12.5 mm) Round Tension Test specimen with 2 in. (50 mm) Gage Length or the Standard S
40、heet- Type, 1/2 in. Wide Rectangular Tension Test Specimen shall be machined and tested as indicated in ASTIyI Method E 8. The Standard Round Tension Test Specimen shall be machined from any point at mid-radius of the bar. “ 4.6 Macroetch test - * 4.6.1 Size of lot - For the purpose of sampibg for m
41、acroetch examination, a lot shall consist of all bars of the same size produced from the. same ingot of steel. In case it is impracticable to identify the material by ingots, a lot shall be limited to 500 pounds of bars of each size and configuration. a * 4.6.2 Sampling - .Unless otherwise specified
42、, a specimen for the macroetch test shall be taken from the uppermost end of the top bar in each ingot as cast. If unable to identify the ingot, specimens shall be taken from each of two . bars in the lot. -. * 4.6.3 Test method - The macroetch test shall be performed in accordance with ASTM Method
43、A 317 on samples selected as specified in 4.6.2. Specimens for the macroetch test shall consist of pieces approximately one-half inch thick cut from the end of the bar. The faces representing the cross-section of the bar shall be finished smooth and flat by a fine machine cut or by grinding. The. et
44、ching solution shall be a 1 to 1 solution of concentrated hydrochloric acid and water. The specimens shail be immersed in the solution at 160 Bo F for 15 to 20 minutes. After etching, the specimens shall be washed in running water or- steam and scrubbed to remove any cIoaking deposits. The specimens
45、 shall then be examined for compliance with 3.5. * 4.7 Rejection and resubmission - If any sample or specimen fails to conform to the requirements of this specification, the lot represented shall be rejected. At the discretion of the contractor/supplier, retest will be permitted. A retest sample of
46、five specimens, one each from five bars in the lot, shall be tested to replace each failed specimen of the original sample. If one of the retest specimens fails, the lot shall be rejected and no further retesting permitted. 5. PREPARATION FOR DELIVERY -. 5.1 Preservation, packaging and packing (see
47、6.2) - Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-16598B L: L:;. tion, conditions and size when prepared for. delivery. The steelbars shall be t:. preserved, packaged, and packed in accordance with MILSTD-163. I: -pl ; . I:. 5.1.2 Level C
48、- Materials shall be prepared for delivery in accordance . . E;:. , . r: . “ Ei . E: 1;: 1.;: L. * v. 5.1.1 Level A - The material shall be properly separated by composi- 1; .- . i: , C . with commercial practice. . * . 5.2 Markings for shipment - Marking andlabeling shall be in , C. accordance with
49、 MIGSTD-163. ,The heat number shall be included in the identification. Iff: . , . i . 1; “ .- 6. NOTES 6.1 Intended use - The material covered by this specification is intended for use in the manufacture of machined parts in which it is necessary to have little change in size with temperature change. The low expansivity characteristics of this material are applicable over a limited range of
