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 revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2013 SAE International All rights reserved. No part of this p
3、ublication may 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: +1 724-776-497
4、0 (outside USA) 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/AMS2649D AEROSPACE MATERIAL SPECIFICATION AMS2649 REV. D Issued 1987-07 Revised 2
5、013-12 Superseding AMS2649C Etch Inspection of High Strength Steel Parts RATIONALE This revision results from a Five Year Review. Glass bead is added as acceptable media for use in surface activation, and alkaline clean solution is added as a rinse solution in lieu of sodium hydroxide solution. 1. S
6、COPE 1.1 Purpose This specification establishes the requirements for etch inspection of steel parts to detect overheating (rehardening or overtempering) caused by abusive machining or grinding, or to detect localized discontinuous carburization. 1.2 Application This process has been used typically f
7、or carburized parts and for bare low-alloy steel parts having tensile strength of 180 ksi (1241 MPa) and higher, but usage is not limited to those applications. The process can also be used to detect abusive grinding or machining in heat treatable steels of lower core hardness. This process may remo
8、ve 0.0001 to 0.0005 inch (2.5 to 12.7 micrometers) from the surface of the part. 1.3 Classification Etchants used in this specification are classified as follows: Type 1 - Nitric acid in water or alcohol with an anti-smut additive Type 2 - Nitric acid in water or alcohol Type 3 - Ammonium persulfate
9、 in water 1.3.1 Type 1 and Type 2 etchants may be used interchangeably. Type 1 immersion or Type 3 swabbing method shall be used when the part cannot be hydrogen embrittlement relieved. 1.3.2 Type 3 etchant shall be applied by swabbing and only used when authorized by the cognizant engineering organ
10、ization. Type 3 is not as sensitive for detecting grinding burns as Type 1 or Type 2. SAE INTERNATIONAL AMS2649D Page 2 of 7 1.4 Safety - Hazardous Materials While the materials, methods, applications, and processes described or referenced in this specification may involve the use of hazardous mater
11、ials, this specification does not address the hazards that 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 precautionary measures to ensure the health and safety of all personne
12、l 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 processor may work to a subsequent revision of a document unless a specific document issue is specified. When th
13、e 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: 877-606-7323 (inside USA and Canada) or 724-7
14、76-4970 (outside USA), www.sae.org. AMS2759/9 Hydrogen Embrittlement Relief (Baking) of Steel Parts ARP1923 Qualification and Certification of Etch Inspectors 2.2 U.S. Government Publications Available from DLA Document Services, Building 4/D, 700 Robbins Avenue, Philadelphia, PA 19111-5094, Tel: 21
15、5-697-6396, http:/quicksearch.dla.mil/. MIL-PRF-16173 Corrosion Preventive Compound, Solvent Cutback, Cold-Application MIL-PRF-32033 Lubrication Oil, General Purpose, Preservative (Water-Displacing, Low Temperature) 3. TECHNICAL REQUIREMENTS 3.1 Preparation 3.1.1 Parts to be etch inspected shall be
16、cleaned to remove contaminants that will prevent wetting of the etching solution. The part to be etched shall have a water-break-free surface when held vertically for 30 seconds. Cleaned parts shall not be touched with bare hands prior to inspection. 3.1.2 Surface activation shall be performed as fo
17、llows: 3.1.2.1 When blasting is performed, glass bead, aluminum oxide or silicon carbide media shall be used to produce a matte appearance. Parts that can be damaged by blasting or may trap the blasting media shall not be cleaned by blasting. 3.1.2.2 When sanding or abrading is performed, 180 grit o
18、r finer bonded abrasive shall be used to produce a matte appearance. 3.1.2.3 Alternative methods of surface activation may be used when acceptable to purchaser. 3.2 Solutions 3.2.1 Type 1 Etchant shall be a 3 to 5% by volume solution of 40 Be nitric acid in water or alcohol mixed with an anti-smut a
19、dditive. The etch solution shall be maintained at 60 to 80 F (16 to 27 C). 3.2.1.1 The anti-smut additive shall be chemicals that, when mixed with the etchant, prevent the formation of smut on the surface of etched steel parts (See 8.3). SAE INTERNATIONAL AMS2649D Page 3 of 7 3.2.2 Type 2 Etchant sh
20、all be a 3 to 5% by volume solution of 40 Be nitric acid in water or alcohol. The solution shall be maintained at 60 to 80 F (16 to 27 C). 3.2.2.1 De-Smut shall be 4 to 6% by volume solution of 22 to 23 Be hydrochloric acid in alcohol or water. The solution shall be maintained at 60 to 80 F (16 to 2
21、7 C). 3.2.3 Type 3 Etchant shall be a 10% 1 by weight solution of ammonium persulfate in water maintained at 60 to 80 F (16 to 27 C). The solution shall be applied within 72 hours of mixing. See 8.4. 3.2.4 Rinse Solution 3.2.4.1 Sodium phosphate shall be an aqueous solution containing 0.5 to 1.0 oun
22、ce per gallon (3.7 to 7.5 g/L) of sodium phosphate. The solution shall be maintained at 60 to 180 F (16 to 82 C). 3.2.4.2 Sodium hydroxide shall be an aqueous solution containing 2 to 6% by weight sodium hydroxide. The solution shall be maintained at 60 to 120 F (16 to 49 C). Alkaline cleaning solut
23、ions designed for use with low alloy and carburized steels may be used in lieu of the sodium hydroxide solution. 3.3 Procedure 3.3.1 General 3.3.1.1 Etch time for the solution shall be determined using a sample part of the same alloy with a known overheated condition and in the same heat treat condi
24、tion as the production parts to be processed. Etch time shall be that time required to start turning the part a uniform gray, determined by personnel certified in accordance with 3.5.2. 3.3.1.2 Etching shall be performed under the supervision of personnel certified in accordance with 3.5.2. 3.3.1.3
25、All examinations shall be performed under a light of not less than 200 foot-candles (2153 lx) by personnel certified in accordance with 3.5.2. 3.3.1.4 Parts having areas that cannot be adequately etch inspected due to geometric restrictions shall be inspected by alternative methods or techniques tha
26、t have been approved by the cognizant engineering organization. 3.3.1.5 Parts shall be racked for immersion etching to prevent contact with each other and to ensure uniform etching on all surfaces that are to be inspected. 3.3.2 Type 1 Etch 3.3.2.1 Each part shall be immersed in etch solution confor
27、ming to 3.2.1 the time determined for the sample part. 3.3.2.2 Without permitting any etched part to dry, each part shall be immediately rinsed in overflowing tap or hot (130 to 180 F 55 to 82 C) water for not less than one minute. Parts shall be dried or immersed in water-displacing oil (MIL-PRF-32
28、033) immediately. 3.3.2.3 Dried or oiled parts shall be visually examined. 3.3.3 Type 2 Etch 3.3.3.1 Each part shall be entirely immersed in etch solution conforming to 3.2.2 for the time determined for the sample part. 3.3.3.2 Without permitting etched parts to dry, parts shall be immediately rinse
29、d in overflowing tap water for not less than one minute. 3.3.3.3 Each part shall be immersed in the de-smut solution conforming to 3.2.2.1 for 15 to 120 seconds. 3.3.3.4 Without permitting de-smutted parts to dry, parts shall be immediately rinsed in overflowing tap water for not less than one minut
30、e. SAE INTERNATIONAL AMS2649D Page 4 of 7 3.3.3.5 Parts shall be rinsed with one of the solutions conforming to 3.2.4 for not less than one minute. 3.3.3.5.1 Parts that were immersed in the sodium hydroxide or alkaline cleaning solution shall be rinsed, in tap or hot (130 to 180 F 55 to 82 C) water,
31、 for not less than one minute. Parts shall be dried or immersed in water-displacing oil (MIL-PRF-32033) immediately. 3.3.3.5.2 Parts that were immersed in sodium phosphate solution do not require a water rinse but shall be dried or immersed in water-displacing oil (MIL-PRF-32033). 3.3.3.6 Dried or o
32、iled parts shall be visually examined. 3.3.3.7 Hydrogen Embrittlement Relief Parts that are desmutted with hydrochloric or other reducing acids shall be treated in accordance with AMS2759/9. Such baking shall be performed prior to subjecting the parts to any stress or mechanical operations. 3.3.4 Ty
33、pe 3 Etch (See 1.2). 3.3.4.1 Etch solution conforming to 3.1.3 shall be applied by swabbing or immersing for the time determined for the sample part. 3.3.4.2 Parts shall be rinsed by swabbing with or immersing in clean water followed by swabbing with or immersing in alcohol. Parts shall be dried or
34、immersed in water-displacing oil (MIL-PRF-32033 or equivalent) immediately after rinsing. 3.3.4.3 Dried or oiled parts shall be visually examined. 3.3.4.4 Hydrogen Embrittlement Relief Parts that were immersed in etch solution shall be treated in accordance with AMS2759/9 after the parts are etched
35、and prior to subjecting the parts to any stress or mechanical operations. 3.4 Visual Examination Unless other acceptance standards are specified by the cognizant engineering organization, acceptance criteria shall be as follows: 3.4.1 If no overheating or discontinuous carburization, as applicable,
36、has occurred, the etched surface will be uniform light gray color over the entire area, and the part is acceptable. 3.4.2 Overtempering Areas of parts etching darker, light brown to black, in relation to the surrounding areas have an indication of overtempering or localized carburization. Parts with
37、 this indication are not acceptable and shall be reinspected in accordance with 3.4.6. 3.4.3 Rehardening Areas of parts etching light gray to white surrounded by a light brown or black border have an indication of rehardening. Parts with this indication are not acceptable and shall be reinspected in
38、 accordance with 3.4.6. 3.4.4 Extraneous Indications Etched surfaces with fingerprints, spots, smeared metal, or any other extraneous indications after etching are not acceptable and shall be cleaned, re-etched, and reinspected in accordance with 3.4.6. SAE INTERNATIONAL AMS2649D Page 5 of 7 3.4.5 C
39、arburized Parts 3.4.5.1 Absence of Carburization The absence of carburization in any local area where carburization is required (localized discontinuous carburization) is not acceptable and such parts shall be reinspected in accordance with 3.4.6 3.4.5.2 Unauthorized Carburization The presence of ca
40、rburization in areas that are not specified is not acceptable and such parts shall be reinspected in accordance with 3.4.6. 3.4.6 Reinspection Parts with areas indicating overtempering,rehardening, or absent or unauthorized carburize shall be cleaned in accordance with 3.1, re-etched in accordance w
41、ith the applicable procedure in 3.3, and re-examined in accordance with 3.4 one time only. Recurrence of initial indications shall be cause for rejection. 3.5 Qualification 3.5.1 Solution Qualification 3.5.1.1 The etch solution shall be qualified daily or prior to use by etching a sample part with a
42、 known unacceptable condition such as from overheating, carburization, or decarburization. 3.5.1.2 The etched part shall be examined to confirm that the unacceptable condition (3.5.1.1) can be detected with the solution and the selected etching time. 3.5.2 Inspector Qualification All personnel perfo
43、rming etch inspection in accordance with this specification shall be trained and certified in accordance with ARP1923. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection The inspection source shall be responsible for the performance of all required tests. Purchaser reserves the right
44、to perform any confirmatory testing deemed necessary to ensure that etch inspection results conform to specified requirements. 4.2 Classification of Tests 4.2.1 Acceptance Tests Visual examination (3.4) shall be performed to determine product acceptance. 4.2.2 Periodic Tests Tests to maintain the so
45、lutions (3.5.1) are periodic tests. 4.3 Sampling and Testing Etch inspection shall be performed on all parts or as agreed upon by purchaser and processing . 4.4 Reports The processor (inspection source) shall furnish with each shipment a report showing the type of inspection performed (See 1.2) and
46、the results of the inspection. This report shall include the purchase order number, AMS2649D, part number, and quantity. SAE INTERNATIONAL AMS2649D Page 6 of 7 5. PREPARATION FOR DELIVERY 5.1 identification Parts that have been accepted by etch inspection described herein shall be identified as spec
47、ified in 5.1.1 and 5.1.2. 5.1.1 The letters AE or NE (See 8.2) shall be legibly rubber-stamped on all parts or processing records, unless another method is specified. 5.1.2 The marking shall have no deleterious effect on the parts and shall be sufficiently stable to withstand normal handling. 5.2 Pa
48、ckaging 5.2.1 Parts shall be protected from corrosion during subsequent storage, handling, and shipping, as applicable. Some acceptable methods include either coating with MIL-PRF-32033 or MIL-PRF-16173 Grade 3 corrosion-preventive compound or packaging in commercial volatile-corrosion-inhibiting wr
49、apping. 5.2.2 Inspected parts shall be handled and packaged to ensure the required physical characteristics are preserved. 5.2.3 Packages of inspected parts shall be prepared for shipment in accordance with commercial 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. 6. ACKNOWLEDGMENT T
