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 therefr
2、om, 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 2008 SAE International All rights reserved. No part of this publication may
3、 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: 724-776-4970 (outside USA) F
4、ax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AMS2753CAMS2753CAEROSPACEMATERIALSPECIFICATIONIssued 1985-01 Revised 2008-08 Superseding AMS2753B (
5、R) Liquid Salt Bath Ferritic Nitrocarburizing Non-Cyanide Bath RATIONALEClarified definitions of compound zone and compound layer. 1. SCOPE 1.1 Purpose This specification covers the requirements for an epsilon-iron nitride case on ferrous parts produced by immersion in a low-temperature, agitated, f
6、used salt bath. 1.2 Application Nitrocarburized surfaces have been used typically for increasing the resistance to wear and fatigue on ferrous alloys including carbon steels, low-alloy steels, tool steels, and corrosion-resistant steels, cast irons, and ferrous powder metal products, but usage is no
7、t limited to such applications. 1.2.1 This process is not recommended for use on parts that have been plated with silver, copper, zinc, or cadmium or on parts having copper alloy inserts. 1.3 Safety - Hazardous Materials While the materials, methods, applications, and processes described or referenc
8、ed in this specification may involve the use of hazardous materials, this specification does not address the hazards which may be involved in such use. It is the sole responsibility of the user to ensure familiarity with the safe and proper use of any hazardous materials and to take necessary precau
9、tionary measures to ensure the health and safety of all personnel involved. 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
10、document unless a specific 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.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproductio
11、n or networking permitted without license from IHS-,-,-SAE AMS2753C - 2 -2.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AMS2759 Heat Treatment of Steel Par
12、ts, General Requirements ARP1820 Chord Method of Evaluating Surface Microstructural Characteristics SAE J423 Methods of Measuring Case Depth SAE J864 Surface Hardness Testing with Files 2.2 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken,
13、PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM D 1193 Reagent Water ASTM E 140 Hardness Conversion Tables for Metals (Relationship Between Brinell Hardness, Vickers Hardness, Rockwell Hardness, Rockwell Superficial Hardness, and Knoop Hardness) ASTM E 384 Microhardness of Materials ASTM E 407
14、Microetching Metals and Alloys 2.3 ASM Publications Available from ASM World Headquarters, 9639 Kinsman Road, Materials Park, OH 44073, Tel: 440-338-5151, www.asminternational.org.ASM Handbook, Metallography and Microstructure, 9th Edition 3. TECHNICAL REQUIREMENTS 3.1 Processing Equipment 3.1.1 Nit
15、rocarburizing salts shall consist primarily of a mixture of alkali metal cyanates and carbonates. 3.1.2 Salt Bath The cyanate content of the bath shall be controlled within the range 34 to 38% by weight, determined as cyanate ion. 3.1.3 Parts shall be processed in a salt bath retort-type furnace.3.1
16、.4 Furnace pyrometry shall conform to AMS2750 furnace class 3, instrumentation type D, as a minimum.3.1.5 Thermocouples When load thermocouples are required, they shall be sheath protected to prevent deterioration due to immersion in nitrocarburizing salts. Copyright SAE International Provided by IH
17、S under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AMS2753C - 3 -3.1.6 Agitation The bath shall be agitated by aeration or mechanical means in order to ensure optimum uniformity over the treated surfaces. If aeration is used, it shall bewit
18、h clean, dry, oil-free compressed or plant air equipped with a desiccant air dryer, a flowmeter for measuring air flow, a gauge for air pressure, and a sparging ring as required equipment. The air flow and pressure shall be in accordance with the salt producers recommendations. 3.2 Pretreatment 3.2.
19、1 Hardening Parts requiring core hardening prior to nitrocarburizing, shall be heat treated in accordance with AMS2759, or other procedure acceptable to the cognizant engineering organization, to the required core hardness. Tempering for the specified core hardness shall be performed at a temperatur
20、e not less than 20 Fahrenheit (11 Celsius) degrees above the highest nitrocarburizing temperature to be used. 3.2.2 Surface Condition Prior to nitrocarburizing, parts shall be clean and free of scale, oxide, entrapped sand, mold or core material, metal particles, oil, or grease. Parts must be comple
21、tely dry. Surfaces to be nitrocarburized shall be mechanically or chemically cleaned subsequent to stress relieving and prior to nitrocarburizing. 3.2.3 Stress Relief Steel parts having a hardness of 40 HRC or higher and in which residual stresses may have been introduced by prior mechanical working
22、 or other causes and consequently may crack or change dimensionally during nitrocarburizing shall be stress relieved prior to final part machining. Stress relief shall be performed in accordance with AMS2759 at a temperature not lower than 20 Fahrenheit (11 Celsius) degrees above the nitrocarburizin
23、g temperature. 3.3 Procedures 3.3.1 Preheating Parts shall be preheated in air to a temperature not higher than 900 F (482 C), to ensure drying, to maintain bath temperature, and to avoid thermal shock upon immersion in the nitrocarburizing salt. 3.3.2 Nitrocarburizing Parts shall be immersed and he
24、ld at temperature in the agitated, fused cyanate-based salt bath for a time sufficient to produce the specified depth of total case or compound layer, as determined by the cognizant engineering organization. Total case consists of the combination of compound layer and diffusion zone. Compound layer
25、consists of epsilon iron nitride and, under microscopic examination, appears as a continuous white layer when etched in accordance with ASTM E 407. See 8.5.3.3.2.1 Nitrocarburizing temperature shall be at least 20 Fahrenheit (11 Celsius) degrees below final tempering temperature or precipitation har
26、dening temperature to maintain base material hardness but shall not be lower than 1000 F (538 C) unless otherwise specified by the cognizant engineering organization. 3.3.3 Quenching Following nitrocarburizing, parts shall be intermediate quenched in a fused salt bath in a temperature range of 750 t
27、o 850 F (399 to 454 C) or in water. After parts have stabilized at the bath temperature set point, parts shall be water rinsed or air cooled. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AMS27
28、53C - 4 -3.4 Properties Nitrocarburized parts shall conform to the following requirements, determined on parts or on test specimens. See 4.3.1. 3.4.1 Compound Layer Hardness The layer shall be equivalent of 55 HRC or greater, determined in accordance with SAE J 864 for file hardness. Light load micr
29、ohardness testing of the surface shall be performed when specified. See 8.7. 3.4.2 Depth of compound layer shall conform to drawing or customer requirements, and shall be determined in accordance with procedures of SAE J423, microscopic method at not less than 500X magnification. See 8.6 for suggest
30、ed compound layer thicknesses 3.4.3 Quality of Compound Layer 3.4.3.1 Not less than three fields shall be examined at 500X magnification employing acceptable quantitative metallographic procedures of line intercept or grid analysis (as described in ASM Handbook, 9th Edition, Metallography and Micros
31、tructure, pages 123 to 134). The upper half of the total compound-thickness, as in 3.4.2, shall not contain more than 50% residual porosity and oxides in any one field viewed. The compound layer at the substrate interface and the lower quarter of the total compound thickness shall not exhibit residu
32、al porosity and oxides exceeding 5% for steel and corrosion-resistant steel components and 15% for cast iron components.3.4.3.2 For parts treated in liquid ferritic nitrocarburizing baths using sulfur bearing salts, the resultant compound layer shall be free of sulfur. Quantitative surface analysis
33、shall be performed to verify the absence of sulfur. 3.4.4 Case hardness shall be as shown in Table 1, determined by microhardness measurements at a depth not greater than 0.001 inch (0.025 mm) below the compound layer in accordance with ASTM E 384 or by the chord method of ARP1820 on prepared cross
34、sections of the nitrocarburized case using Knoop or other appropriate hardness tester acceptable to the cognizant engineering organization.3.4.4.1 For corrosion resistant steels, microhardness measurement shall be taken at the mid-point of the total case, as measured in accordance with procedures SA
35、E J423 microscopic method at not less than 500X magnification. TABLE 1 - CASE HARDNESS MaterialHardness, minimum HK100 or equivalent Carbon Steels 300 Low-Alloy Steels 460 Tool a heat treatment load shall be all parts of the same part number treated simultaneously in the same set of solutions and pr
36、esented for processors inspection at one time.4.3.1 Not less than one part, or sample (when permitted), shall be processed for evaluation for each test requirement: 4.3.2 Sample Configuration Test pins or specimens of the same nominal composition and heat treat condition as the parts may be processe
37、d with the heat treatment load when permitted by the cognizant engineering organization for destructive tests. 4.4 Approval 4.4.1 The process and control factors or a preproduction part, or both, whichever is specified, shall be approved by the cognizant engineering organization before production pa
38、rts are supplied. 4.4.2 The processor shall make no significant change to materials, processes, or control factors from those on which the approval was based, unless the change is approved by the cognizant engineering organization. A significant change is one which in the judgment of the cognizant e
39、ngineering organization could affect the properties or performance of the parts. 4.4.3 The processor shall have a copy of the procedure available for review by purchasers cognizant quality assurance organization. It shall include a full description of all equipment and procedures used to process par
40、ts. 4.5 Reports The heat treating processor shall furnish, with each shipment of parts, a certified quality assurance report, traceable to the heat treat control number(s), stating that the parts were processed in accordance with the requirements of this specification AMS2753C (or other applicable s
41、pecification). The report shall include: purchase order number, part number or product identification, alloy, temper/strength designation, quantity of parts in the shipment, identification of furnace(s) used, actual thermal processing times and temperatures used. Additionally, when applicable, the r
42、eport shall also include actual test results, (e.g., hardness, conductivity, tensile, shear) and a statement of their conformance/nonconformance to requirements. This data shall be reported in accordance with the heat treaters documented procedures. Copyright SAE International Provided by IHS under
43、license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE AMS2753C - 6 -4.6 Resampling and Retesting If any specimen used in the above tests fails to meet the specified requirements, disposition of the parts may be based on the results of testing three ad
44、ditional specimens for each original nonconforming specimen. Failure of any retest specimen to meet the specified requirements shall be cause for rejection of the parts represented. Results of all tests shall be reported. 4.6.1 If any acceptance test fails to meet specified test requirements, the pa
45、rts in that load may be retested. Alternatively, all parts in the load may be inspected for the nonconforming attribute, and the nonconforming parts may be reprocessed as defined herein, and retested. After reprocessing, parts shall meet the dimensions on the drawing.4.6.2 If the result of any perio
46、dic test fails to meet specified test requirements, the process is nonconforming. No additional parts shall be treated until the process is corrected and new specimens are treated and tested. Results of all tests shall be recorded and, when requested, reported. Purchasers shall be notified of all pa
47、rts treated since the last acceptable test.5. PREPARATION FOR DELIVERY 5.1 Parts shall be handled and packaged to ensure that the required physical characteristics of the nitrocarburized parts are preserved. 5.2 Packages of nitrocarburized parts shall be prepared for shipment in accordance with comm
48、ercial practice and in compliance with applicable rules and regulations pertaining to the handling, packaging, and transportation of the parts to ensure carrier acceptance and safe delivery. Packaging shall conform to carrier rules and regulations applicable to the mode of transportation.6. ACKNOWLE
49、DGMENT A processor shall mention this specification number and its revision letter in all quotations and when acknowledging purchase orders. 7. REJECTIONS Parts on which the compound layer does not conform to this specification, or to modifications authorized by the cognizant engineering organization, will be subject to rejection. 8. NOTES 8.1 A change bar (|) located in the left margin is for convenience of the user in locating areas where technical revi
