Standard Specification for Tool Steels Alloy 1

Transcription

1 Designation: A68 8 Standard Specification for Tool Steels Alloy This standard is issued under the fixed designation A68; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon ( ) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense.. Scope. This specification covers the chemical, mechanical, and physical requirements for available wrought alloy tool steel products..2 These products, which ude hot or cold finished bar, plate, sheet, strip, rod, wire, or forgings, are normally fabricated into tools, dies, or fixtures. The selection of a material for a particular application will depend upon design, service conditions, and desired properties.. The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 2. Referenced Documents 2. ASTM Standards: 2 A Test Methods and Definitions for Mechanical Testing of Steel Products A6 Practice for Macroetch Testing of Tool Steel Bars A6 Specification for Tool Steel High Speed A Practices for Packaging, Marking, and Loading Methods for Steel Products for Shipment E Guide for Preparation of Metallographic Specimens E Test Methods for Chemical Analysis of Steel, Cast Iron, Open-Hearth Iron, and Wrought Iron E4 Test Methods for Determining the Inclusion Content of Steel E9 Practice for Sampling Steel and Iron for Determination of Chemical Composition E2 Practice for Numbering Metals and Alloys in the Unified Numbering System (UNS) 2.2 Military Standard: This specification is under the jurisdiction of ASTM Committee A on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A.29 on Tool Steels. Current edition approved Oct., 28. Published October 28. Originally approved in 9. Last previous edition approved in 2 as A68. DOI:.2/A For referenced ASTM standards, visit the ASTM website, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards volume information, refer to the standard s Document Summary page on the ASTM website. Withdrawn. The last approved version of this historical standard is referenced on MIL-STD-6 Steel Mill Products, Preparation for Shipment and Storage 4 2. Federal Standards: Fed. Std. No. 2 Marking and Shipment (Civil Agencies) 4 Fed. Std. No. 8 Continuous Identification Marking of Iron and Steel Products Other Standards: SAE J86 Recommended Practice for Numbering Metals and Alloys (UNS). Classification. Material in accordance with this specification is classified by chemical composition. Types correspond to respective AISI designations... Hot Work Tool Steels, Identification H:... Types H to H9 are characterized by a controlled chromium content along with other alloying elements. The first four, containing molybdenum, offer excellent toughness and high hardenability and are frequently used in cold work applications requiring toughness at relatively high hardness levels....2 Types H2 to H26 are characterized by a controlled tungsten content along with other alloying elements. These steels offer greater resistance to the softening effect of elevated service temperatures but exhibit a lower degree of toughness.... Types H4 to H4 are low-carbon modifications of molybdenum high speed tool steels (Note ) and have characteristics similar to the tungsten types. NOTE High-speed tool steels are covered in Specification A6...2 Cold Work Tool Steels, Identification A Types A2 to A cover a wide range of carbon and alloy contents but all have high hardenability and may be hardened in air. The low carbon Types A8 and A9 have less wear resistance but offer greater toughness than others in this group. Type A, with high carbon and vanadium, offers exceptional wear resistance but at a very low level of toughness... Cold Work Tool Steels, Identification D Types D2 to D are characterized by high carbon and high chromium 4 Available from the Standardization Documents, Order Desk, Bldg. 4, Section D Robbins Ave. Philadelphia, PA 9-94 Attn: NPODS. Available from the Society of Automotive Engineers, 4 Commonwelth drive, Warrendale, PA 96. Copyright ASTM International, Barr Harbor Drive, PO Box C, West Conshohocken, PA , United States. Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2

2 A68 8 contents and exhibit high resistance to abrasion. The types containing molybdenum may be hardened in air and offer a high degree of dimensional stability in heat treatment...4 Cold Work Tool Steels, Identification O Types O to O are low-alloy types that must be hardened by quenching in oil. Sizes over about 2 in. ( mm) in cross section usually exhibit lower interior hardness... Shock-Resisting Steels, Identification S Types S to S vary in alloy content but are intended for shock-resisting applications...6 Special-Purpose Tool Steels, Identification L Types L2 to L6 are low-alloy steels with a wide range of carbon content. The low-carbon types are generally used for structural applications requiring good levels of toughness, while the high-carbon types may be used for short-run tools... Special-Purpose Tool Steels, Identification F Types F to F2 are high-carbon steels with varying tungsten content used primarily for relatively short-run fine edge cutting tools...8 Mold Steels, Identification P:..8. Types P2 to P6 are very low-carbon steels and must be carburized after machining or hubbing Types P2 and P2 are usually supplied in the prehardened condition and can be placed in service directly after machining. 4. Ordering Information 4. Orders for material under this specification shall ude the following information, as required to describe adequately the desired material: 4.. Class of material (hot work tool steel, etc.), 4..2 Type (H, D2, etc.), 4.. Shape (sheet, strip, plate, flat bar, round bar, square bar, hexagon bar, octagon, special shapes), 4..4 Dimensions (thickness, width, diameter, length), 4.. Finish (hot rolled, forged, blasted or pickled, cold drawn, machined, ground, precision ground and polished), 4..6 Condition (annealed, hardened and tempered, etc.), 4.. ASTM designation and year of issue, and 4..8 Special requirements.. Materials and Manufacture. Unless otherwise specified, material covered by this specification shall be made by an electric melting process. It shall be made from ingots or slabs that have been reduced in cross section in such a manner and to such a degree as to ensure proper refinement of the solidification structure. 6. Chemical Composition 6. An analysis of each heat of steel shall be made by the manufacturer to determine the percentage of the elements specified, and these values shall conform to the requirements for chemical composition specified in Table. If requested or required, the chemical composition shall be reported to the purchaser or his representative. 6.2 Analysis may be made by the purchaser from finished bars and forgings by machining off the entire cross section and drilling parallel to the axis of the bar or forging at any point midway between the center and surface in accordance with the latest issue of Practice E9. The chemical analysis of the drilling chips shall be made in accordance with the latest issue of Test Methods E. The chemical composition thus determined shall not vary from the limits specified in Table.. Hardness Requirements Hardness Requirements. Annealed hardness values shall be obtained in accordance with the latest issue of Test Methods and Definitions A, and shall not exceed the Brinell hardness values (or equivalent Rockwell hardness values) specified in Table 2..2 Specimens for determination of minimum response to hardening shall be -in. (6.4-mm) thick disks cut so as to represent either the full cross-sectional area or that midway between the center and outer surface of the material. If the material form or size does not lend itself to accurate hardness determination on -in. thick cross-sectional disks, then longitudinal specimens may be used for hardness testing. Examples are round bars less than in. (2. mm) in diameter or sheet. In this case, the specimen shall be a minimum of in. (6 mm) in length and parallel flats shall be ground on the original mill surfaces. The specimens shall be heat treated as prescribed in Table..2. The hardness of the specimen after the specified heat treatment shall meet the minimum hardness value for the particular type of steel shown in Table. Rockwell C tests should be used where possible but light load tests may be necessary on thin specimens. These tests should be specified by agreement between the seller and the purchaser. The hardness value shall be obtained in accordance with the latest issue of Test Methods and Definitions A, and shall be the average of at least five readings taken in an area midway between the center and surface of the largest dimension of the crosssectional specimen or along the parallel surfaces of the longitudinal specimen. 8. Macrostructure 8. Specimens for the determination of the macrostructure shall represent the entire cross-sectional area in the annealed condition and be prepared in accordance with the latest issue of Practice A6. Material supplied to this specification shall be capable of exhibiting a structure free of excessive porosity, segregation, slag, dirt or other nonmetallic usions, pipe, checks, cracks, and other injurious defects. 8.2 Macroetch severity levels for center porosity and ingot pattern, illustrated photographically in Practice A6, shall not exceed the ratings specification in Table 4 for the appropriate material size and composition. More stringent requirements are available by agreement between seller and purchaser. 9. Decarburization 9. Specimens for the determination of decarburization shall represent a cross section of the material and be prepared in accordance with the latest issue of Guide E. Material supplied to this specification shall be capable, when examined at 2 times or greater magnification, of not exceeding the values given in Tables -8 for the appropriate size and shape of material. Lower limits of decarburization may be specified by agreement between the seller and purchaser. Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2 2

3 TABLE A68 8 Chemical Requirements, % A UNS Carbon Manganese C Phosphorus, Sulfur, Designation min max min max max Type Silicon Chromium Vanadium Tungsten Molybdenum max min max min max min max min max min max T28 H T28 H T282 H T28 H T284 H T289 H Co T282 H T2822 H T282 H T2824 H T282 H T2826 H26.4. E T284 H4.6. E T2842 H42.. E T284 H4..6 E T2 A T A T4 A T A T6 A T A T8 A T9 A Ni.2. T A Ni. 2. T42 D T4 D T44 D T4 D Co 2.. T4 D T O T2 O T6 O T O T49 S T492 S T494 S T49 S T496 S T49 S T622 L T62 L Nickel T626 L T66 F T662 F T62 P T6 P T64 P T6 P T66 P T62 P T62 P2 F A Chemistry limits ude product analysis tolerances. Unless otherwise specified, nickel plus copper equal. % max for all types. B New designation established in accordance with Practice E2 and SAEJ86. C Manganese limit is. % max for H resulfurized. D Where specified, sulfur may be.6 to. % to improve machinability. E Available in several carbon ranges. F Also contains..2 % aluminum. 9.2 Material ordered as ground and polished or ground finished or machine finished shall be free of scale and decarburization.. Permissible Variations for Dimensions. Permissible variations for dimensions shall not exceed the applicable limits stated in Tables Workmanship, Finish, and Appearance. All alloy tool steels shall be free of heavy scale, deep pitting, laps, porosity, injurious segregations, excessive nonmetallic usions, seams, cracks, checks, slivers, scale marks, dents, soft and hard spots, pipes, or any defects that would Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2

4 A68 8 TABLE 2 Type Maximum Brinell Hardness in Annealed or Cold-Drawn Condition Annealed BHN Cold Drawn BHN Type Annealed BHN Cold Drawn BHN H O H O H O H O 24 2 H H S H S H S H S H S H S H L H L 2 24 H L H F 2 24 A F A A P2... A P 4... A P4... A P... A P A P2 A... P2 A... D D D D D A Normally furnished in prehardened condition. detrimentally affect the suitability of the material after removal of the recommended stock allowance. 2. Sampling 2. Each particular shipment of a heat of steel by type, size, and shape shall be considered a lot and must conform to the provisions of this specification.. Inspection. Unless otherwise specified in the contract or purchase order, the supplier is responsible for the performance of all inspection requirements as specified herein. The supplier may utilize his own facilities or any other acceptable to the purchaser..2 When specified in the purchase order, the inspector representing the purchaser shall have access to the material subject to inspection for the purpose of witnessing the selection of samples, preparation of test pieces, and performance of the tests. For such tests, the inspector shall have the right to indicate the pieces from which samples will be selected. Otherwise the seller shall report to the purchaser, or his representative, the results of the chemical analysis and the physical and mechanical property tests made in accordance with this specification.. The purchaser may perform any of the inspections set forth in this specification on the as-received material where such inspections are deemed necessary to ensure that supplies and services conform to the prescribed requirements. 4. Rejection and Rehearing 4. Unless otherwise specified, any rejections based on tests made in accordance with this specification shall be reported to the seller within days from the date of receipt of the material. 4.2 Material that shows injurious defects subsequent to its acceptance by the purchaser shall be rejected and the seller notified. 4. Samples tested in accordance with this specification that represent rejected material shall be preserved for days from the date of the test report. In case of dissatisfaction with the results of the test, the seller may make claim for a rehearing within that time.. Packaging, Loading, and Package Marking. Packaging and Loading:.. Unless otherwise specified, shipments shall be packaged and loaded in accordance with Practices A...2 When specified in the contract or order, and for direct procurement by or direct shipment to the government, when Level A is specified, preservation, packaging, and loading shall be in accordance with the Level A requirement of MIL-STD Markings:.2. Shipments shall be properly marked with the name or brand of manufacturer, purchaser s name and order number, designation (ASTM A68), heat number, grade or type, and where appropriate, the size, length, and weight. Unless otherwise specified, method of marking is at the option of the manufacturer..2.2 When specified in the contract or order, and for direct procurement by or direct shipment to the government, marking for shipment, in addition to any requirements specified in the contract or order, shall be in accordance with MIL-STD-6 for military agencies, and in accordance with Fed. Std. No. 2 for civil agencies..2. For government procurement by the Defense Supply Agency, steel shall be continuously marked for identification in accordance with Fed. Std. No Keywords 6. alloy; cold work tool steels; decarburization; hardness; hot work tool steels; macrostructure; tool steel Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2 4

5 TABLE Heat-Treating Requirements NOTE The austenitizing temperatures are stipulated for the response to hardening test only. Other combinations of austenitizing and tempering temperatures may be used for particular applications. NOTE 2 Preheating temperature may be 62 F (4 C), but austenitizing and tempering temperatures shall be 6 F (.6 C). If samples are austenitized in salt, the sample shall be at the austenitizing temperature for the minimum time shown. If a controlled atmosphere furnace is used, the sample shall be at the austenitizing temperature for to min ( to 2 min for D types). The time at temperature is the time after the sample reaches the austenitizing temperature. This range of time is given because of the difficulty in determining when the sample reaches temperature in some types of controlled atmosphere furnaces. NOTE Those steels tempered at 4 F (24 C) shall have a single 2-h temper, while those tempered at 9 (), 2 (2), or 2 F (649 C) shall be double-tempered for 2 h each cycle. NOTE 4 The P types shall not be tested for response to heat treatment since P2 to P6 are used in the carburized condition and P2 are normally furnished in the prehardened condition. NOTE Specimens as described in.2 shall be capable of producing the specified minimum hardness when the stipulated heat treating parameters are used. Type Preheat Temperature, F ( C) Austenitizing Temperature, F ( C) Salt Bath Controlled Atmosphere Furnaces A68 8 Austenitizing Time (minutes) Quench Medium Tempering Temperature, F ( C) Minimum Hardness, RC H 4 (88) 8 () 8 (24) Air 2 (2) H 4 (88) 82 (996) 8 () Air 2 (2) H2 4 (88) 82 (996) 8 () Air 2 (2) H 4 (88) 82 (996) 8 () Air 2 (2) 2 H4 4 (88) 9 (8) 92 (2) Air 2 (2) H9 4 (88) 2 () 2 (9) Air 2 (2) H2 4 (88) 2 () 2 (9) Air 2 (2) 2 H22 4 (88) 2 () 2 (9) Air 2 (2) H2 (86) 22 (246) 2 (26) Oil 2 (649) 42 H24 4 (88) 22 (24) 222 (28) Air 2 (2) H2 4 (88) 22 (22) 22 (246) Air 2 (2) 44 H26 (84) 22 (246) 2 (26) Air 2 (2) 8 H4 4 (88) 22 (6) 2 () Air 2 (2) 6 H42 4 (88) 2 (9) 22 (24) Air 2 (2) 6 H4 4 (88) 2 () 2 (9) Air 2 (2) 8 A2 4 (88) 2 (94) (94) Air 4 (24) 6 A 4 (88) (968) 8 (982) Air 4 (24) 6 A4 2 (6) (84) (8) Air 4 (24) 6 A6 2 (649) 2 (829) (84) Air 4 (24) 8 A (86) (94) (968) Air 4 (24) 6 A8 4 (88) 82 (996) 8 () Air 9 () 6 A9 4 (88) 82 (996) 8 () Air 9 () 6 A 2 (649) 4 (82) (86) Air 4 (24) 9 D2 (86) 82 (996) 8 () 2 Air 4 (24) 9 D (86) (94) (968) 2 Oil 4 (24) 6 D4 (86) 8 (982) 82 (996) 2 Air 4 (24) 62 D (86) 82 (996) 8 () 2 Air 4 (24) 6 D (86) 92 (2) 9 (66) 2 Air 4 (24) 6 O 2 (649) 4 (88) 4 (82) Oil 4 (24) 9 O2 2 (649) 4 (88) 4 (82) Oil 4 (24) 9 O (88) 4 (82) Oil 4 (24) 9 O 2 (649) (8) 6 (8) Oil 4 (24) 62 S 2 (6) 2 (94) (94) Oil 4 (24) 6 S2 2 (6) 62 (88) 6 (899) Brine 4 (24) 8 S4 2 (6) 62 (88) 6 (899) Oil 4 (24) 8 S 2 (6) 62 (88) 6 (899) Oil 4 (24) 8 S6 4 (88) (92) 2 (94) Oil 4 (24) 6 S 2 (6) 2 (94) (94) Air 4 (24) 6 L2 2 (649) (8) 6 (8) Oil 4 (24) A L 2 (649) 2 (829) (84) Oil 4 (24) 62 L6 2 (649) (86) 2 (829) Oil 4 (24) 8 F 2 (649) 2 (829) (84) Brine 4 (24) 64 F2 2 (649) 2 (829) (84) Brine 4 (24) 64 A.4. % carbon type. Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2

6 Bar Size, A68 8 TABLE 4 Macroetch Standards (Maximum Allowable Rating) A Low-Alloy Tool Steels B High-Alloy Tool Steels C Porosity Ingot Pattern Porosity Ingot Pattern Up to 2 (.8), to (.8 to 6), to 4 (6 to 2), to (2 to 2), to 6 (2 to 2), (2) As negotiated between seller and purchaser. A Refer to macroetch photographs in Practice A6. B Low-alloy tool steels ude H-, A2-6, A8-, AO,S,L,F, and P types. C High-alloy tool steels ude H4-4, D2-, and A. TABLE Maximum Decarburization Limits (Rounds, Hexagons and Octagons Maximum Limit Per Side) NOTE The recommended minimum allowance for machining prior to heat treatment is 2 % greater than the maximum decarburization allowed. Ordered Size, Hot Rolled Forged Cold Drawn Up to (2.),. (.).... (.) to (2. to 2.4),.2 (.64)....2 (.64) to 2 (2.4 to.8),.8 (.9).8 (.4).8 (.96) 2 to (.8 to 6),. (.2). (.9). (.2) to 4 (6 to 2),. (.8).96 (2.44). (.8) 4 to (2 to 2),.9 (2.29).6 (2.9)... to 6 (2 to 2),.2 (.).6 (.4)... 6 to 8 (2 to 2),....6 (4.6)... 8 to (2 to 24),....6 (4.6)... TABLE 6 Maximum Decarburization Limits (Hot Rolled Square and Flat Bars Maximum Limit Per Side) NOTE The recommended minimum allowance for machining prior to heat treatment is 2 % greater than the maximum decarburization allowed. Specified Thickness, to ( to 2.), to(2.to 2.4), to 2 (2.4 to.8), 2 to (.8 to 6), to 4 (6 to 2), to ( to 2.) to (2. to 2.4), to2 (2.4 to.8), 2to (.8 to 6), Specified Widths, to4 (6 to 2), 4to (2 to 2), to6 (2 to 2), 6to (2 to 8), to8 (8 to 2), 8to9 (2 to 229), 9to2 (229 to 4), A B.2 (.).2 (.).24 (.6).28 (.).2 (.8).6 (.9).4 (.2).44 (.2).48 (.22).48 (.22).48 (.22).2 (.).26 (.66).2 (.8).8 (.9).44 (.2).4 (.).62 (.).66 (.68).8 (.98).82 (2.8).96 (2.44) A....6 (.9).6 (.9).6 (.9).4 (.2).44 (.2).2 (.2).6 (.42).6 (.2).6 (.2).6 (.2) B....6 (.9).42 (.).46 (.).6 (.42).64 (.6).82 (2.8).9 (2.29).98 (2.49).2 (2.9).8 (2.4) A (.2).2 (.2).6 (.42).6 (.42).6 (.2).6 (.2).64 (.6).68 (.).2 (.8) B (.2).6 (.42).6 (.2).2 (.8).86 (2.8).98 (2.49).2 (2.84).8 (.).22 (.) A (.6).64 (.6).68 (.).68 (.).2 (.8).2 (.8).8 (2.).8 (2.) B (.6).2 (.8).82 (2.8).94 (2.9). (2.9).22 (.). (.).6 (.4) A (2.).8 (2.).86 (2.8).92 (2.4).94 (2.9). (2.4). (2.4) B (2.).9 (2.29). (2.4).2 (.).2 (.).2 (.). (.8) Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2 6

7 A68 8 TABLE Maximum Decarburization Limits (Forged Square and Flat Bars Maximum Limit Per Side) NOTE The recommended minimum allowance for machining prior to heat treatment is 2 % greater than the maximum decarburization allowed. Specified Thickness, to 2 (2.4 to.), 2 to (.8 to 6), to 4 (6 to 2), 4 to (2 to 2), Specified Width, to 6 (2 to 2), 6 to (2 to 8), to 8 (8 to 2), 8 to 9 (2 to 229), 9 to 2 (229 to ), to, (2. to A.8 (.9).42 (.).48 (.2).2 (.2).6 (.42).62 (.).66 (.68).2 (.8).8 (2.) 2.4), B.48 (.22).6 (.42). (.8).8 (2.).94 (2.9). (2.9).2 (.).2 (.).2 (.) to 2, (2.4 to A.8 (.4).62 (.).66 (.68). (.8).4 (.8).8 (.88).84 (2.).94 (2.9).6 (2.69).8), B.8 (.4).66 (.68).8 (.98).86 (2.8). (2.4).4 (2.9).2 (.).2 (.).2 (.) 2 to (.8 to A....8 (2.).84 (2.).88 (2.24).92 (2.4).98 (2.49).6 (2.69).4 (2.9).26 (.2) 6), B....8 (2.).92 (2.4).98 (2.49).6 (2.69).8 (.).6 (.4).6 (.4).6 (.4) to 4 (6 to A (2.9).6 (2.69).2 (2.84).2 (.).2 (.).4 (.6).8 (4.) 2), B (2.9).6 (2.69).2 (2.84).2 (.).2 (.).4 (.6).8 (4.) 4 to (2 to A (.2). (.).8 (.).46 (.).6 (.96). (4.2) 2), B (.2). (.).8 (.).46 (.).6 (.96). (4.2) to 6 (2 to A (.8).8 (4.).66 (4.22).6 (4.4).88 2), B (.8).8 (4.).66 (4,22).6 (4.4).88 6 to (2 to A (4.4).86 (4.2).86 (4.2).98 (.) 8) B (4.4).86 (4.2).86 (4.2).98 (.) TABLE 8 Maximum Decarburization Limits (Cold Drawn Square and Flat Bars Maximum Limits Per Side) NOTE The recommended minimum allowance for machining prior to heat treatment is 2 % greater than the maximum decarburization allowed. Specified Thickness, to ( to 2.), to (2. to 2.4), Specified Width, to 2 (2.4 to.8), 2 to (.8 to 6), to 4 (6 to 2), 4 to 2 to 2), to ( to 2.), A.2 (.).2 (.).24 (.6).28 (.).2 (.8).6 (.9) B.2 (.).26 (.66).2 (.8).8 (.9).44 (.2).4 (.) to (2. to 2.4), A....6 (.9).6 (.9).6 (.9).4 (.2).44 (.2) B....6 (.9).42 (.).46 (.).6 (.42).64 (.6) to 2 (2.4 to.8), A (.2).2 (.2).6 (.42)... B (.2).6 (.42).6 (.2)... Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2

8 A68 8 TABLE 9 Hot-Rolled Bars (Rounds, Squares, Octagons, Quarter Octagons, Hexagons Size Tolerance) Specified Sizes, Size Tolerances, Under To (2.),. (.).2 (.) to (2. to 2.4),. (.).6 (.4) to (2.4 to 8.),.6 (.).2 (.) to 2 (8. to.8),.8 (.2).2 (.64) 2 to 2 (.8 to 6.),. (.2). (.6) 2 to (6. to 6.2),. (.2).4 (.2) to 4 (6.2 to.6),.2 (.). (.2) 4 to (.6 to 9.),. (.8).6 (.2) to 6 (9. to 6.),.8 (.46). (2.4) 6 to 8 (6. to 2.2),.2 (.). (.8) TABLE Forged Bars (Rounds, Squares, Octagons, Hexagons Size Tolerances) A Specified Sizes, Size Tolerances, Under to 2 (2.4 to.8),. (.6).6 (.2) 2 to (.8 to 6),. (.6).8 (2.) to (6 to 2),.6 (.2).2 (.8) to (2 to.8).2 (.8).8 (4.) to 9 (.8 to 229),.8 (4.).2 (.92) A Out-of-section tolerances to be three fourths of the total tolerance. TABLE Rough-Turned Round Bars (Size Tolerance) A Specified Sizes, B Size Tolerance, Under to (9. to 8.),.. (.24) to (8. to.8),.. (.8) to 4 (.8 to.2),.. (.9) 4 to 6 (.2 to 4),..62 (.6) 6 to (4 to 2.6),..94 (2.4) Please consult producer A Out-of-round tolerances to be one half of the total tolerance. B Consult producer for oversize allowance and decarburization limits for all sizes. TABLE 2 Cold-Drawn Bars (Rounds, Octagons, Quarter Octagons, and Hexagons Size Tolerances) A Size Range, Tolerance, Plus and Minus to (6.4 to 2.), excl.2 (.) to (2. to 2.4), excl.2 (.6) to2 (2.4 to 69.8),. (.8) A Out-of-round tolerances to be one half of the total thickness. Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2 8

9 A68 8 TABLE Centerless Ground Bars Rounds (Diameter Tolerances) A Diameter Range, Tolerance, Under to (6.4 to 2.), excl. (.8). (.8) to (2. to.8), excl.2 (.).2 (.) to 4 (.8 to.2), excl. (.8). (.8) A Out of round tolerances to be of the total tolerance. Specified Widths, TABLE 4 Hot-Rolled Flat Bars (Width and Thickness Tolerances Width Tolerances) A Specified Widths, Width Tolerances, Under To (2.4),.6 (.4). (.9) to (2.4 to 6),. (.9).4 (.9) to (6 to 2),.4 (.9).6 (.6) to (2 to 8),.6 (.6).94 (2.9) to (8 to 24),.8 (.98).2 (.8) to 2 (24 to ),.94 (2.9).6 (.96) To, to (6.4 to 2.), Thickness Tolerances for Specified Thicknesses, to (2. to 2.4), to 2 (2.4 to.8), 2 to (.8 to 6), to 4 (6 to 2), Under Under Under Under Under Under To (2.4),.6 (.). (.2).8 (.2).2 (.). (.2).6 (.4) to 2 (2.4 to.8),.6 (.).4 (.6).8 (.2).6 (.4). (.2).2 (.).2 (.).24 (.6) to (.8 to 6),.6 (.).8 (.46).8 (.2).2 (.). (.2).24 (.6).2 (.).2 (.69).26 (.66).4 (.86) to 4.8 (.2).2 (.). (.2).22 (.6). (.).24 (.6).24 (.6). (.6).2 (.8).42 (.).4 (.2).48 (.22) (6 to 2), 4 to. (.2).2 (.).2 (.).24 (.6). (.8). (.6).2 (.69). (.89).2 (.8).42 (.).42 (.). (.2) (2 to 2), to 6.2 (.).2 (.).4 (.6). (.6).8 (.46). (.6). (.6). (.89).6 (.9).46 (.).44 (.2).4 (.) (2 to 2), 6 to.4 (.6).2 (.69).6 (.4).2 (.8).8 (.46). (.89). (.6).4 (.2).6 (.9).48 (.22).46 (.).6 (.42) (2 to 8), to.8 (.46). (.6).2 (.). (.89).24 (.6).4 (.2). (.89).4 (.4).4 (.2).4 (.).2 (.2).64 (.62) (8 to 24), to 2.2 (.). (.89).2 (.64).4 (.2). (.6).4 (.4).4 (.2). (.2).46 (.).6 (.2).6 (.42).2 (.8) (24 to ), A Out of square tolerance to be of total width tolerance max. Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2 9

10 Specified Widths, TABLE Forged Flat Bars (Width Tolerances) Width Tolerances, Specified Widths, Under to (2.4 to 6),. (.9).8 (.98) to (6 to 2),.62 (.).2 (.8) to (2 to 8),.2 (.8).8 (4.) to 9 (8 to 229),.8 (4.).2 (.92) To (2.4), to (2.4 to 6), A68 8 Thickness Tolerances for Specified Thicknesses, to (6 to 2), to (2 to 8), to 9 (8 to 229), Under Under Under Under Under to (2.4 to.6 (.4). (.9). (.9).8 (.98) ), to (6 to. (.9).62 (.).4 (.9).94 (2.9).62 (.).2 (.8) ), to (2 to.4 (.9).94 (2.9).62 (.).2 (.8).8 (.98).6 (.96).2 (.8).8 (4.) ), to 9 (8 to.62 (.).2 (.8).8 (.98).6 (.96).94 (2.9).8 (4.).6 (.96).29 (.6).8 (4.).2 (.92) 229), TABLE 6 Cold Drawn Square and Flat Bars (Size Tolerances) Tolerance, Size Range, Plus and Minus to (6.4 to 9.),.2 (.) to (9. to 8.),. (.8) (8.).4 (.) TABLE Drill Rod, Rounds, Polished or Ground (Size Tolerances) A NOTE Out-of-round to be of total tolerance maximum. Specified Size, Standard Manufacturing Tolerance,, plus and minus Precision Tolerance,, plus and minus Up to.24 (.),. (.8).2 (.).2 to.499 (.8 to 2.),. (.).2 (.6). to. (2. to 8.),. (.2). (.) A Out-of-round tolerances to be one half of the total tolerance. TABLE 9 Precision Ground Square and Flat Bars (Thickness and Width Tolerances ) NOTE Surface Finish, µin. (.89 µm) rms maximum. Free of decarburization. Thickness, Tolerance, Under Thickness Up to (.8),. (.). (.) to 2 (.8 to.8),.2 (.).2 (.) Width to 4 (2. to.6),.. (.) TABLE 2 Hot-Rolled or Forged Bars and Billets (Tolerances for Machine Cut Lengths) Specified Sizes Apply to Rounds, Squares, Hexagons, Octagons, and Width of Flats, Tolerances for Specified Lengths, 4 ft (4.2 m) max, Under To 9 (229), (9.) 9 to 2 (229 to ), (2.) 2 to 8 ( to 4), (9.) 8 (4) (2.4) TABLE 8 Drill Rod, Shapes Other than Rounds, Cold Drawn (Size Tolerances) A Tolerances,, Specified Size, plus and minus Up to, excl. (.) to (6.4 to 9.), excl. (.2) to (9. to 2.4),. (.8) A Out-of-round tolerances to be one half of the total tolerance. Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2

11 TABLE 2 A68 8 Straightened Hot-Rolled Annealed Bars or Cold- Finished Bars (Straightness Tolerances ) This table does not apply to flat bars having a width to thickness ratio of 6 to or greater. Measurement is taken on the concave side of the bar with a straightedge. Bars are furnished to the following straightness tolerances: Hot rolled bars: in. in any ft, but may not exceed in. (no. of ft in length/) The foregoing formula applies also to bars under ft in length. (.2 mm in any.4 m, but may not exceed.2 mm (no. of m in length/.4). The foregoing formula applies also to bars under.4 m in length.) Cold finished bars: in. in any ft, but may not exceed in. (no. of ft in length/) The foregoing formula applies also to bars under ft in length. (.6 mm in any.4 m, but may not exceed.6 mm (no. of m in length/.4). The foregoing formula applies also to bars under.4 m in length.) TABLE 22 Forgings, Disks, Rings and Rectangular Blocks (Allowances for Machining; Tolerances Allowances) NOTE Unmachined tool steel forgings are furnished to size and surface allowances for machining and tolerances over allowances. Experience indicates that the allowances and tolerances in the tabulation below are satisfactory for many applications. When width and thickness differ, each dimension carries its individual allowance and tolerance in accordance with the tabulation; also, the ID and OD take their respective allowances and tolerances. NOTE 2 When forgings are ordered, the purchaser should state whether the sizes are the forged or the finished sizes. The minimum sizes ordered for forgings should be the finished sizes plus allowances for machining; and the ordered forged sizes are subject to applicable tolerances. Finished Size Diameters or Dimensions of Blocks, Diameters of Disks and Rings and Dimension of Blocks Allowance for Machining Finished Size, Tolerance the Allowance, Plus Minus Up to (6), (.2) (.2) to (6 to 2), to (2 to 8), to (8 to 24), to 2 (24 to ), (9.) (9.) 2 to ( to 8), (.) (.) to 8 (8 to 4), (2.) (2.) 8 to 24 (4 to 6), (.9) (2.) 24 to 2 (6 to 8), (9.) (2.) 2 to 4 (8 to 6), (22.2) (2.) Ring forgings: for the OD, use the same allowances and tolerances shown in the above tabulation; for the ID, double the tolerances shown in the above tabulation. Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2

12 2 Finished Diameter, Up to (6), (.2) to (6 to 2), (.2) to (2 to 8), to (8 to 24), to 2 (24 to ), 2 to ( to 8), to 8 (8 to 4), 8 to 24 (4 to 6), 24 to 2 (6 to 8), 2 to 4 (8 to 6), Finished Diameter, Up to (6), to (6 to 2), to (2 to 8), to (8 to 24), to 2 (24 to ), (.) 2 to ( to 8), (2.) to 8 (8 to 4), (2.) 8 to 24 (4 to 6), (2.) 24 to 2 (6 to 8), 9 (4.) 2 to 4 (8 to 6), 9 (4.) TABLE 2 Forgings, Disks, Rings, and Rectangular Blocks (Allowances for Machining: Tolerances Allowances) Thickness of Disks and Ring Forgings Up to (6), to (6 to 2), Finished Thickness, to (2 to 8), to (8 to 24), to 2 (24 to ), (.2) (.2) 2 to (4 to 8), (.2) (.2) (9.) (9.) (.2) (.2) (9.) (9.) to 8 (8 to 4), (9.) (9.) (9.) (9.) (9.) (9.) (.) (.) Finished Thickness, A (.) (.) 8 to 24 (4 to 6), (9.) (9.) (9.) (9.) (9.) (9.) (9.) (.) (.) (2.) (2.) (9.) (.) (.) (2.) (2.) 24 to 2 (6 to 8), (9.) (.) (.) (.) (2.) (2.) (9.) (.) (.) (.) (2.) (2.) 2 to 4 (8 to 6), Allowance Tolerance Plus Minus Plus Minus Plus Minus Plus Minus Plus Minus Allowance Tolerance Plus Minus Plus Minus Plus Minus Plus Minus Plus Minus (.) (2.) (2.) (2.) 9 (4.) 9 (4.) (2.) (2.) (.9) (.9) (2.) (2.) (.9) (.9) (.9) (.9) (9.) (9.) (.9) (.9) (9.) (9.) (9.) (9.) (9.) (9.) (9.) (22.2) A Forgings processed to the above allowances are free of decarburization and surface defects when machined or ground to the finished size by removal of equal amounts from opposite surfaces. (9.) (22.2) A68 8 Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2

13 A68 8 TABLE 24 Hot Rolled Sheet and Plate (Tolerances for Thickness and Minimum Allowances for Machining) Thickness, Thickness Tolerance, A,B Machining Allowance, C,D Up to.2 (.64)..6 (.). (.).2 to.62 (.64 to.6)..2 (.). (.).62 to.9 (.6 to 2.4)..6 (.4). (.8).9 to.2 (2.4 to.2)..2 (.). (.8).2 to.8 (.2 to 4.8)..28 (.).8 (.46).8 to.2 (4.8 to 6.4).. (.2).2 (.8).2 to. (6.4 to 9.)..6 (.2). (.89). to. (9. to 2.).. (.8). (.89). to. (2. to 2.4).. (2.4).6 (.6). to. (2.4 to 8.)..2 (.8).6 (.6). to 2. (8. to.8)..2 (.8). (.9) 2. to 4. (.8 to.6)..2 (6.).94 (2.6) A Thickness is measured along the longitudinal edges of the sheet or plate at least in. (9. mm), but not more than. in. (6.2 mm) from the edge. B All tolerances are over the specified thickness. C Maximum decarburization limits are 8 % the allowance per side for machining. D Additional cleanup for deviations from flatness may be added. Consult with producer. TABLE 2 Hot Rolled Trimmed Sheet and Plate (Tolerances for Width and Length) A Thickness, Tolerance, B Width Length Up to.8..2 (.8).2 (6.).8 to. (4.8 to 9.).8 (4.6).2 (6.). to 4. (9. to.6).2 (6.).2 (6.) A Tolerances shown are for all trimming methods. B All tolerances are on the plus side of the specified width or length. TABLE 26 Hot Rolled Sheet and Plate (Tolerances for Flatness) Thickness, Tolerances, A Up to.2 (.8).. (9.).2 to. (.8 to 2.).. (2.). to. (2. to 8.).. (9.2). to 4. (8. to.6)..2 (6.) A Maximum deviation from a horizontal flat surface in any ft (. m). TABLE 2 Hot Rolled Trimmed Sheet and Plate (Tolerances for Camber) NOTE Camber is the deviation of a side edge from a straight line. Measurement is taken by placing a ft(.2 m) straight edge on the concave side and measuring the greatest distance between the sheet or plate edge and the straight edge. Maximum camber =.2 in. in any ft (.8 mm in any.2 m) Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2

14 TABLE 28 Machined Square and Flat Bars (Size, Straightness and Squareness Tolerances, ) NOTE Bars shall be free of surface imperfections and decarburization and furnished oversize as shown. Surface finish shall be 2 µin. (.8 µm) rms maximum for ground bars, and 2 µin. (6.6 µm) rms maximum for machined (milled) bars. Specified Thickness Thickness A Width A Machined or Plate Machined Cut From Plate size Tolerance size Tolerance size Tolerance to 4, (2. to.6). (.8) +.2, (.). (.8) +.2, (.). (.8) +.62, (.9) 4 to 6, (.6 to 2.4).62 (.9) +., (.9).62 (.9) +., (.9).62 (.9) +.62, (.9) Straightness Tolerances in. in any ft, but may not exceed in. no. of ft in length/ The foregoing formula applies also to bars under ft in length..6 mm in any.4 m, but may not exceed.6 mm no. of m in length/.4 The foregoing formula applies also to bars under.4 m in length. Squareness Tolerances The width and thickness dimensions specified must be attainable when surfaces are subsequently made to be parallel and square. Closer limits of squareness may be agreed upon between seller and purchaser. A For larger widths and thicknesses than shown, refer to producer. A68 8 SUPPLEMENTARY REQUIREMENTS One or more of the following supplementary requirements shall apply only when specified by the purchaser in the inquiry, contract, and order. Details of these supplementary requirements shall be agreed upon by the seller and the purchaser. S. Ultrasonic Quality S. Material shall be ultrasonically tested at appropriate stages of the manufacture to ensure the quality, when and as agreed upon between seller and purchaser. S2. Cleanliness S2. In special situations such as where the surface finish of the part requires optimum polishing characteristics, the cleanliness of the steel shall be ascertained in accordance with the latest issue of Test Methods E4. The permissible limits shall be agreed upon between seller and purchaser. ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentioned in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility. This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. This standard is copyrighted by ASTM International, Barr Harbor Drive, PO Box C, West Conshohocken, PA , United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above address or at (phone), (fax), or service@astm.org ( ); or through the ASTM website ( 4 Copyright by ASTM Int'l (all rights reserved); Wed Sep 29 4:2: EDT 2