1、AEROSPACE MATERIAL SPECIFICATION AMS6378 REV. G Issued 1961-07 Reaffirmed 2010-05 Revised 2014-08 Superseding AMS6378F Steel Bars 1.0Cr - 0.20Mo - 0.45Se (0.39 - 0.48C) (4142H Modified) Die-Drawn, 130 ksi (896 MPa) Yield Strength Free Machining (Composition similar to UNS K11542) RATIONALE AMS6378G
2、results from a Five Year Review and update of this specification that revises macrostructure, decarburization and reporting. 1. SCOPE 1.1 Form This specification covers a free-machining, low-alloy steel in the form of round bars 3.50 inches (88.9 mm) and under in nominal diameter. 1.2 Application Th
3、ese bars have been used typically for parts, such as shafts, axles, pins, fasteners, gears, and screw machine parts, 0.50 inch (12.7 mm) and under in nominal section thickness at time of heat treatment, which are normally used at hardness of 30 to 36 HRC and which do not require a high degree of duc
4、tility, but usage is not limited to such applications. 2. APPLICABLE DOCUMENTS The issue of the following documents in effect on the date of the purchase order forms a part of this specification to the extent specified herein. The supplier may work to a subsequent revision of a document unless a spe
5、cific document issue is specified. When the referenced document has been cancelled and no superseding document has been specified, the last published issue of that document shall apply. 2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877
6、-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AMS2251 Tolerances, Low-Alloy Steel Bars AMS2259 Chemical Check Analysis Limits, Wrought Low-Alloy and Carbon Steels _ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state
7、 of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five year
8、s at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2014 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, e
9、lectronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE va
10、lues your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AMS6378G SAE INTERNATIONAL AMS6378G Page 2 of 6 AMS2370 Quality Assurance Sampling and Testing, Carbon and Low-Alloy Steel, Wrought Products and Forging Stock AMS2806 Identification, Bar
11、s, Wire, Mechanical Tubing, and Extrusions, Carbon and Alloy Steels and Corrosion and HeatResistant Steels and Alloys AS1182 Standard Stock Removal Allowance, Aircraft-Quality and Premium Aircraft-Quality Steel Bars and Mechanical Tubing 2.2 ASTM Publications Available from ASTM International, 100 B
12、arr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM A 370 Mechanical Testing of Steel Products ASTM E 112 Determining Average Grain Size ASTM E 350 Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and Wroug
13、ht Iron ASTM E 381 Macroetch Testing Steel Bars, Billets, Blooms, and Forgings ASTM E 384 Knoop and Vickers Hardness of Materials 3. TECHNICAL REQUIREMENTS 3.1 Composition Shall conform to the percentages by weight shown in Table 1, determined by wet chemical methods in accordance with ASTM E 350, b
14、y spectrochemical methods, or by other analytical methods acceptable to purchaser: TABLE 1 - COMPOSITION Element min max Carbon 0.39 0.48 Manganese 0.70 1.10 Silicon 0.15 0.35 Phosphorus - 0.040 Sulfur - 0.040 Chromium 0.75 1.20 Molybdenum 0.15 0.25 Selenium 0.03 0.06 Nickel - 0.25 Copper - 0.35 3.1
15、.1 Check Analysis Composition variations shall meet the applicable requirements of AMS2259. 3.2 Condition Bars shall be elevated-temperature die-drawn. 3.2.1 Temperatures for die drawing shall be selected significantly above room temperature but below the transformation range to produce a uniform st
16、ructure of deformed pearlite and ferrite providing good machinability. SAE INTERNATIONAL AMS6378G Page 3 of 6 3.3 Properties Bars shall conform to the following requirements; tensile and hardness testing shall be performed in accordance with ASTM A 370: 3.3.1 Macrostructure Visual examination of tra
17、nsverse full cross-sections from bars and billets, etched in hot hydrochloric acid in accordance with ASTM E 381, shall show no pipe or cracks. Porosity, segregation, inclusions, and other imperfections shall be no worse than the macrographs of ASTM E 381 shown in Table 2. TABLE 2 - MACROSTRUCTURE L
18、IMITS Section Size Square Inches Section Size Square Centimeters Macrographs Up to 36, incl Up to 232, incl S2 - R1 - C2 Over 36 to 133, incl Over 232 to 858, incl S2 - R2 - C3 Over 133 Over 858 Note 1 Note 1 Limits for larger sizes shall be agreed upon by producer and purchaser. The purchaser shall
19、 have written approval of the agreement from the cognizant engineering organization. 3.3.2 Average Grain Size Shall be ASTM No. 5 or finer determined in accordance with ASTM E 112 . 3.3.3 Decarburization 3.3.3.1 Bars ordered ground, turned, or polished shall be free from decarburization on the groun
20、d, turned, or polished surfaces. 3.3.3.2 Decarburization of bars to which 3.3.3.1 is not applicable shall be not greater than shown in Table 3. TABLE 3A - MAXIMUM TOTAL DEPTH OF DECARBURIZATION LIMITS, INCH/POUND UNITS Nominal Diameter Inches Total Depth of Decarburization Inch Up to 0.375, incl 0.0
21、10 Over 0.375 to 0.500, incl 0.012 Over 0.500 to 0.625, incl 0.014 Over 0.625 to 1.000, incl 0.017 Over 1.000 to 1.500, incl 0.020 Over 1.500 to 2.000, incl 0.025 Over 2.000 to 2.500, incl 0.030 Over 2.500 to 3.000, incl 0.035 Over 3.000 to 3.500, incl 0.040 TABLE 3B - MAXIMUM TOTAL DEPTH OF DECARBU
22、RIZATION LIMITS, SI UNITS Nominal Diameter Millimeters Total Depth of Decarburization Millimeters Up to 9.52, incl 0.25 Over 9.52 to 12.70, incl 0.30 Over 12.70 to 15.88, incl 0.36 Over 15.88 to 25.40, incl 0.43 Over 25.40 to 38.10, incl 0.51 Over 38.10 to 50.80, incl 0.64 Over 50.80 to 63.50, incl
23、0.76 Over 63.50 to 76.20, incl 0.89 Over 76.20 to 88.90, incl 1.02 SAE INTERNATIONAL AMS6378G Page 4 of 6 3.3.3.3 Decarburization shall be measured by the metallographic method or by a traverse method using microhardness testing in accordance with ASTM E 384. The microhardness method shall be conduc
24、ted on a hardened but untempered specimen protected during heat treatment to prevent changes in surface carbon content. Depth of decarburization, when measured by the microhardness method, is defined as the perpendicular distance from the surface to the depth under that surface where there is not fu
25、rther increase in hardness. Such measurements shall be far enough away from any adjacent surface to be uninfluenced by any decarburization on the adjacent surface. In case of dispute, the depth of decarburization determined using the microhardness traverse method shall govern. 3.3.3.3.1 When determi
26、ning the depth of decarburization, it is permissible to disregard local areas provided the decarburization of such areas does not exceed the above limits by more than 0.005 inch (0.13 mm) and the width is 0.065 inch (1.65 mm) or less. 3.3.4 Tensile Properties Specimens, cut from the center of bars 1
27、.50 inches (38.1 mm) and under in nominal diameter and at mid-radius on sizes larger than 1.50 inches (38.1 mm), shall conform to Table 4. TABLE 4 - MINIMUM TENSILE PROPERTIES Property Value Tensile Strength Yield Strength at 0.2% Offset Elongation in 4D Reduction of Area 150 ksi (1034 MPa) 130 ksi
28、( 896 MPa) 5% 20% 3.3.4.1 Mechanical property requirements for product outside the size range covered by 1.1 shall be agreed upon between producer and purchaser. 3.3.5 Hardness Shall be 302 to 341 HB, or equivalent, (See 8.2) but bars shall not be rejected on the basis of hardness if the tensile pro
29、perties are acceptable, determined on specimens taken from the same sample as that with nonconforming hardness or from another sample with similar nonconforming hardness. 3.4 Quality Bars, as received by purchaser, shall be uniform in quality and condition, sound, and free from foreign materials and
30、 from imperfections detrimental to usage of the bars. 3.4.1 Bars ordered as die drawn, or ground, turned, or polished shall, after removal of the standard stock removal allowance in accordance with AS1182, be free from seams, laps, tears, and cracks open to the machined, ground, turned, or polished
31、surface. 3.5 Tolerances Bars shall conform to all applicable requirements of AMS2251, except that tolerances for diameter shall be as shown in Table 5. TABLE 5A - DIAMETER TOLERANCES, INCH/POUND UNITS Nominal Diameter Inches Tolerance, Inch Minus Only Up to 0.375, incl 0.003 Over 0.375 to 1.500, inc
32、l 0.005 Over 1.500 to 2.500, incl 0.006 Over 2.500 to 3.500, incl 0.007 SAE INTERNATIONAL AMS6378G Page 5 of 6 TABLE 5B - DIAMETER TOLERANCES, SI UNITS Nominal Diameter Millimeters Tolerance, Millimeter Minus Only Up to 9.52, incl 0.08 Over 9.52 to 38.10, incl 0.13 Over 38.10 to 63.50, incl 0.15 Ove
33、r 63.50 to 88.90, incl 0.18 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection The vendor of bars shall supply all samples for vendors tests and shall be responsible for the performance of all required tests. Purchaser reserves the right to sample and to perform any confirmatory testi
34、ng deemed necessary to ensure that the bars conform to specified requirements. 4.2 Classification of Tests All technical requirements are acceptance tests and shall be performed on each heat or lot as applicable. 4.3 Sampling and Testing Shall be in accordance with AMS2370. 4.4 Reports The producer
35、of the product shall furnish with each shipment a report showing the producer identity and country where the metal was melted (e. g., final melt in the case of metal processed by multiple melting operations), results of chemical composition and macrostructure for each heat and for tensile properties
36、 and hardness of each lot, and stating that the product conforms to the other technical requirements. This report shall include the purchase order number, heat and lot numbers, AMS6378G, size, and quantity. 4.5 Resampling and Retesting Shall be in accordance with AMS2370. 5. PREPARATION FOR DELIVERY
37、 5.1 Sizes Except when exact lengths or multiples of exact lengths are ordered, straight bars will be acceptable in mill lengths of 6 to 20 feet (1.8 to 6.1 m), but not more than 10% of any shipment shall be supplied in lengths shorter than 10 feet (3 m). 5.2 Identification Shall be in accordance wi
38、th AMS2806. 5.3 Protective Treatment Bars ordered as die drawn, ground, turned, or polished shall be protected from corrosion prior to shipment. 5.4 Packaging Bars shall be prepared for shipment in accordance with commercial practice and in compliance with applicable rules and regulations pertaining
39、 to the handling, packaging, and transportation of the bars to ensure carrier acceptance and safe delivery. SAE INTERNATIONAL AMS6378G Page 6 of 6 6. ACKNOWLEDGMENT A vendor shall include this specification number and its revision letter in all quotations and when acknowledging purchase orders. 7. R
40、EJECTIONS Bars not conforming to this specification, or to modifications authorized by purchaser, will be subject to rejection. 8. NOTES 8.1 A change bar (|) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been ma
41、de to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, nor in documents that contain editorial changes only. 8.2 Hardness conve
42、rsion tables for metals are presented in ASTM E 140. 8.3 Terms used in AMS are clarified in ARP1917. 8.4 Dimensions and properties in inch/pound units and the Fahrenheit temperatures are primary; dimensions and properties in SI units and the Celsius temperatures are shown as the approximate equivalents of the primary units and are presented only for information. 8.5 Purchase documents should specify not less than the following: AMS6378G Size or bars desired Quantity of bars desired. PREPARED BY AMS COMMITTEE “E”
