1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state 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 there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2010 SAE International All rights reserved. No part of this publication m
3、ay be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, 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 U
4、SA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AMSH6875B AEROSPACE MATERIAL SPECIFICATION AMS-H-6875 REV. B Issued 1998-11 Reaffirmed 2006-0
5、4 Revised 2010-11 Superseding AMS-H-6875A Heat Treatment of Steel Raw Materials RATIONALE AMS-H-6875B results from clarifying furnace class per AMS2750. NOTICE The initial SAE publication of this document was taken directly from U.S. Military Standard MIL-H-6875H, Amendment 2. This SAE Standard may
6、retain the same part numbers established by the original military document. Any requirements associated with Qualified Products Lists (QPL) may continue to be mandatory for DoD contracts. Requirements relating to QPLs have not been adopted by the SAE for this standard and are not part of this SAE do
7、cument. 1. SCOPE 1.1 Scope This specification covers the requirements for heat-treatment of four classes of steel (See 1.2) and the requirements for furnace equipment, test procedures and information for heat-treating procedures, heat-treating temperatures and material (See 6.3) test procedures. Thi
8、s specification is applicable only to the heat treatment of raw material (See 6.3.1); it does not cover the requirements for the heat treatment of steel parts (See 3.4 and 6.3.2). This specification also describes procedures that, when followed, will produce the desired properties and material quali
9、ties within the limitations of the respective alloys tabulated in Tables 1A, 1B, 1C and 1D. Alloys other than those specifically covered herein may be heat treated using all applicable requirements of this specification. 1.1.1 Limitations Unless otherwise specified, this specification is not applica
10、ble to heating or to intermediate (non-final) heat treatment, of raw material, e.g., for hot working. Processes not covered include deliberate surface heat-treating and specialized heat-treating, such as induction hardening, flame hardening, carburizing, nitriding; however, this specification may be
11、 referenced for equipment and controls. Austempering, ausbay quenching and martempering may be used when specified by the cognizant engineering organization. SAE AMS-H-6875B Page 2 of 22 1.2 Classification Steels covered by this specification are classified into the following four classes. Unless ot
12、herwise specified, the process and equipment requirements in this specification refer to all classes of steel tabulated in Tables 1A, 1B, 1C, and 1D, respectively. Class A - Carbon and low alloy steel Class B - Martensitic corrosion-resistant steel Class C - Austenitic corrosion-resistant steel Clas
13、s D - Precipitation-hardening and maraging steel 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 specific
14、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 Commonweath Drive, Warrendale, PA 15096-0001, Tel: 877-606-73
15、23 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AMS2418 Plating, Copper AMS2424 Plating, Nickel, Low-Stressed Deposit AMS2750 Pyrometry AMS2759 Heat Treatment of Steel Parts, General Requirements AMS2759/3 Heat Treatment, Precipitation-Hardening Corrosion-Resistant and Maragin
16、g Steel Parts AMS-QQ-N-290 Nickel Plating (Electrodeposited) 2.2 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM A 262 Detecting Susceptibility to Intergranular Attack in Austenitic Sta
17、inless Steels ASTM A 370 Mechanical Testing of Steel Products ASTM C 848 Youngs Modulus, Shear Modulus, and Poissons Ratio for Ceramic Whitewares by Resonance ASTM D 3520 Quenching Time of Heat Treating Fluids (Magnetic Quenchometer Test) ASTM E 3 Metallographic Specimens, Preparation of ASTM E 8 /
18、E 8M Tension Testing of Metallic Materials SAE AMS-H-6875B Page 3 of 22 ASTM E 10 Brinell Hardness of Metallic Materials ASTM E 18 Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials ASTM E 384 Knoop and Vickers Hardness of Materials 3. REQUIREMENTS 3.1 Equipment 3.1.1 Furnace
19、Media and Protective Coatings 3.1.1.1 Atmosphere for Classes A, B, C and D Steel Parts The gaseous medium for heat treating Classes A, B, C and D steel parts above 1250 F shall be air/products of combustion, argon, helium, hydrogen, nitrogen, or blends of these gases, vacuum, exothermic, endothermic
20、, nitrogen based, or dissociated ammonia conforming to the requirements shown in Table 1. Supplementary protective coatings, in accordance with 3.3.1.3, may be used where necessary. TABLE 1 - FURNACE ATMOSPHERE REQUIREMENTS Atmosphere Class A 1/ Class B 1/ Class C 1/ Class D 1/ Air/Products of Combu
21、stion X 2/ X 2/ X X Argon 3/ X X X X Helium 3/ X X X X Hydrogen 3/ X X 7/ X X 5/ Nitrogen 3/ 6/ X 8/ X X X10/ Vacuum X X X X11/ Exothermic 4/ X X X No Nitrogen based or endothermic 4/ X 8/ X No No Dissociated Ammonia 3/ 9/ No No X No 1/ X - Denotes atmosphere acceptable for use on that designated cl
22、ass of steel with or withoutlimitations. 2/ Unless otherwise specified, an air/product of combustion atmosphere shall be limited toprecipitation hardening, tempering, stress relieving and 1400 F transformation treatments. An air/product of combustion atmosphere may be used for treatment above 1400 F
23、 for Classes Aand B material that will have a minimum of 0.020 inch metal removed from all surfaces afterheat treatment or that have been protected by electroplates. 3/ Dew point shall be not higher than -40 F at the exit of the working zone. 4/ Atmosphere shall be refined or blended to avoid a chan
24、ge in carbon content at the surface ofthe material as specified in 3.3.3. A product of combustion at -40 F maximum dew point (e.g.,endothermic) may be used for class A material that allows 0.003 inch maximum partial decarburization at the surface. Exothermic atmosphere permissible only for heat trea
25、tment ofclass A mill products. 5/ Acceptable up to 1950 F. 6/ Nitrogen atmosphere does not include nitrogen from dissociated ammonia 7/ Only acceptable when tempered at 1000 F or above. Acceptable for annealing. 8/ Class A steels may be fine grain copper plated 0.002 to 0.005 inch thick in accordanc
26、e with AMS2418 or nickel plated per AMS2424 or AMS-QQ-N-290 or equivalent as a supplementary surface protection. Other supplementary protective coatings may be used if approved by thecognizant engineering organization. 9/ Permissible only for annealing of mill products providing residual ammonia at
27、the outlet of thegenerator does not exceed 15 ppm. 10/ The use of a nitrogen atmosphere shall be limited to heat treating temperatures of 1400 F andbelow. A nitrogen atmosphere may be used for heat treatment above 1400 F provided aminimum of 0.020 inches of metal is subsequently removed from all sur
28、faces of heat treatedmaterial. 11/ Nitrogen is not permitted as a partial pressure above 1400 F. Nitrogen may be used as a backfill quench for vacuum heat treatments performed at or below 1925 F. SAE AMS-H-6875B Page 4 of 22 3.1.1.2 Atmospheres for Mill Products Furnaces for mill products shall be s
29、upplied with gases of a consistent analysis such that the product meets the requirements of the appropriate material specification. Furnaces, gases, and gas generators shall be controlled. Ducts and working zones shall be sealed to prevent contamination by outside gases. Vacuum furnaces shall have a
30、 calibrated recording instrument for sensing the vacuum in the vacuum chamber. All atmosphere furnaces and gas supply lines shall be purged with the designated and approved atmosphere gas for the specific steel to be heat treated. 3.1.1.3 Salt Baths Salt baths may be used for the heat treatment of C
31、lasses A and B steels. Salt baths shall be tested initially and at least once each week and shall be adjusted to assure that part surfaces shall be free from general corrosion, carburization and decarburization or intergranular attack in excess of limits specified in 3.3.3. Additives used for adjust
32、ments shall be limited to salts in bath and rectifiers recommended by the salt manufacturer. 3.1.1.4 Temperature Uniformity The design and construction of heating equipment shall be such that the temperature at any point in the furnace working zone or work load shall comply with AMS2750. 3.1.1.5 Tem
33、perature Range and Set Temperature The set temperature on the furnace control instrument shall be such that the load temperature falls within the specified range, taking into account the temperature uniformity of the furnace. In continuous furnaces used to anneal and normalize mill products, a therm
34、al head may be used. The temperature of the mill product shall not exceed the maximum processing temperature. 3.1.2 Pyrometry and Furnace Temperature Control The requirements and procedures for control and testing of furnaces, ovens, salt baths, vacuum furnaces, refrigeration equipment and allied py
35、rometric equipment used for heat treatment shall be in accordance with AMS2750. 3.1.2.1 All furnaces shall be instrumented to a minimum of Type D Instrumentation in accordance with AMS2750. Unless the material specification temperature tolerance or range requires a different furnace class or otherwi
36、se indicated herein, furnace class requirements per AMS2750 are shown in Figure 1: FIGURE 1 - FURNACE CLASS REQUIREMENTS AMS-H-6875 Process AMS2750 Furnace Class Tempering (after hardening) of - D6AC and 9Ni-4Co (Class A) alloy steels - other (Class A) low alloy steels - 220 ksi (1517 MPa) UTS and h
37、igher Class 2 (10 F/6 C) Aging of (Class D) PH stainless steels at 1025 F (552 C) and below Class 2 (10 F/6 C) Aging of (Class D) PH stainless steels above 1025 F (552 C) Class 3 (15 F/8 C) All Other Processes Class 5 (25 F/14 C) 3.1.3 Quenching Equipment 3.1.3.1 Quench Baths Quench baths shall perm
38、it complete immersion of material, provide for adequate circulation of the media or agitation of material, provide a means for indicating the temperature of the media and for cooling and heating, as applicable. Baths shall be adequate to produce the required properties in the most massive material t
39、o be quenched. SAE AMS-H-6875B Page 5 of 22 3.1.3.1.1 Oil-Quenching Baths The oil-quenching medium shall be between 60 F and 160 F at the beginning of the quenching operation and shall not exceed 200 F at any time during the quenching operation, unless otherwise approved by the cognizant engineering
40、 organization. The temperature of the oil quenching media shall not exceed the manufacturers recommended operating range. Quench oil used in integral quench vacuum furnace systems, where the quench chamber is below atmospheric pressure, shall be vacuum degassed at approximately the maximum recommend
41、ed temperature for the quenchant initially and after each major addition of oil. 3.1.3.1.2 Aqueous Polymer Quenchants Aqueous polymer quenchants may be used as permitted in Tables 1A through 1D. The temperature of the aqueous polymer quenchant baths shall not exceed the manufacturers recommended ope
42、rating range. These baths shall also be adequately circulated to assure homogeneity of the aqueous polymer quenchant media. 3.1.3.1.3 Quenching from Salt Bath Furnaces Water-quenching baths employed in cooling steel parts that have been heated in salt-bath furnaces should be provided with an inflow
43、of fresh water to prevent a concentration of dissolved salts in the tanks. Polymer quenching baths when used in conjunction with salt bath furnaces shall be monitored weekly so that the salt content of the bath shall not exceed 6% by weight of the bath. All salt residues shall be removed from parts
44、processed in salt-bath furnaces or quenched in brine, during or immediately following quenching. 3.1.3.1.4 Alternative Quenchants In lieu of the stated methods in Tables 1A through 1D, steam, air, water sprays, inert gases, polymers, molten salts or other commercial quenching media or processes may
45、be used when approved by the cognizant engineering organization, providing equivalence with respect to mechanical properties and corrosion resistance, as applicable to the material and its application, can be substantiated. Equivalence tests shall be as specified by the cognizant engineering organiz
46、ation. Where air quenching is permitted in Tables 1A through 1D, argon and helium may be used; other inert gases may be substituted when approved by the cognizant engineering organization. 3.1.3.2 Location of Quenching Equipment Quenching equipment shall be located in such a manner and handling faci
47、lities shall function with sufficient speed to prevent the initiation of transformation or sensitization prior to quenching. 3.1.4 Miscellaneous Equipment Suitable jigs, fixtures, trays, hangers, racks, ventilators, and so on, shall be employed as necessary for the proper handling of the work and fo
48、r maintenance of the major items of equipment. The use of heat-treating fixtures or fixture materials where the contact with or proximity to the material could contaminate the material or reduce the heating, cooling or quenching rates to less than required for complete transformation or through-hard
49、ening of the material shall not be permitted. 3.1.5 Cleaning Equipment Equipment shall be provided to clean material in accordance with 3.3.1.1. Where toxic or harmful cleaners are employed, they shall be used in compliance with the applicable health and safety regulations. SAE AMS-H-6875B Page 6 of 22 3.2 Thermal Treatment 3.2.1 Rate of heating Heating rates shall be controlled to prevent damage to the
