1、This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. AUGUST 2015 Page 1 of 8 NAVISTAR, INC. Material, Parts, and Process Specifications
2、 (MPAPS) NUMBER: MPAPS A-40 Former Designation: CEMS A-40 Sections A and B TITLE: Case Hardening Ferrous Materials CURRENT REV No.: 1508 DATE: August 2015 WRITTEN/EDITED BY: J. Sponzilli APPROVED BY: R. Goluch SUPERSEDES: Rev No, Date 1408, August 2014 PRINTED COPIES OF THIS DOCUMENT MUST BE VERIFIE
3、D FOR CURRENT REVISION This specification may involve hazardous materials, equipment, and procedures. This specification does not purport to address all of the safety issues associated with its use. The user is responsible to consult appropriate safety and health practices and to determine the appli
4、cability of regulatory limits prior to use. Change Notice: Revise nitriding requirements. Added section covering core hardness requirements. Editorial changes. 1.0 APPLICATION This specification covers diffusion based surface hardening of ferrous parts for the purpose of enhancing their fatigue, wea
5、r and/or corrosion resistance properties. 2.0 SCOPE MPAPS A-40 covers the following case hardening processes for ferrous parts: A. Carburizing and Carbonitriding - thermochemical processes of case hardening that involve the diffusion of carbon or carbon and nitrogen into the surface of ferrous mater
6、ials at elevated temperatures B. Nitriding and Ferritic Nitrocarburizing - thermochemical processes of case hardening that involve the diffusion of nitrogen or nitrogen and carbon into the surface of ferrous materials at low temperatures between 930OF to 1050 OF 2.1 Restricted Chemical Substances Ef
7、fective January 1, 2007, all product supplied to the requirements of this specification must comply with the requirements of the MPAPS B-50 specification. 3.0 REFERENCE DOCUMENTS Unless otherwise specified, the latest issue of all referenced standards shall apply. The following Specifications, Stand
8、ards, and Regulations are referenced in this specification. Quality System Standard ISO 9001 or TS-16949 CFR Title 29, Part 1910 SAE J1081 SAE J864 NAVISTAR Manufacturing Std. MS-D-13 SAE J404 NAVISTAR Engineering Design Std A-16 ASTM A355 NAVISTAR MPAPS B-50 ASTM E140 ASTM E384 NUMBER: MPAPS A-40 T
9、ITLE: Case Hardening Ferrous Materials REVISION: 1508 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. AUGUST 2015 Page 2 of 8 A. C
10、ARBURIZING and CARBONITRIDING The following sections, prefixed with an (A), apply to carburized and carbonitrided components only. A4.0 CLASSIFICATION Case hardened steels are classified by the depth of the hardened surface layer. See Tables I and II. A5.0 GENERAL REQUIREMENTS A5.1 Light Cases Light
11、 cases have depths of 0.020 inch (0.50 mm) or less. The case depth will be measured by the total case method, unless otherwise specified. Classification, requirements, and case hardening process will be as shown in Table I (refer to Section A5.5 for measurement of case properties). TABLE I CLASSIFIC
12、ATION (1) AND REQUIREMENTS (2) (3) Light Cases Navistar Class Total Case Depth Surface Hardness Case Hardening Process Quench in mm 1A 0.002-0.006 0.05-0.15 File Resistant Carbonitriding Oil or Water 1B File Hard 2A 0.006-0.010 0.15-0.25 File Resistant Carbonitriding Gas 2B Rockwell 89-93 HR15N or F
13、ile Hard Oil or Water 3 0.010-0.020 0.25-0.50 Rockwell 89-93 HR15N Carbonitriding or Carburizing Oil or Water 3A File Resistant Gas (1) Where deemed feasible on particular parts and after consultation with the Materials Engineer, more than one Class should be specified. See “Appendix” for further di
14、scussion. (2) All case-hardened steels shall be produced using fully-killed, fine-grain practices. (3) Heat treating will be carried out in such a manner as to avoid excessive brittleness in the finished part. Parts which require specific properties will have the requirements and methods of test det
15、ailed on the drawing. A5.2 Heavy Cases Heavy cases are those with case depths in excess of 0.020 inch (0.51 mm) and will be produced by carburizing. All heavy case carburized parts will be tempered at 350F (175C) minimum. The effective case depth method will be used for determination of case depth o
16、n the tempered part, unless otherwise specified on the engineering drawing. Classification will be as shown in Table II (refer to Section A5.5 for measurement of case properties). A5.3 Surface Hardness Whenever a class from Table II is specified, it is also necessary to specify the desired surface h
17、ardness. For gears and splined shafts, the specified hardness is generally Rockwell 57-63 HRC, while roller bearing components are usually specified Rockwell 60 HRC minimum. For certain applications, it may be desirable to specify file hardness. If a surface hardness range with a minimum less than R
18、ockwell 55 HRC is specified, special effective case hardness must be designated on the drawing (see Section 10.0). NUMBER: MPAPS A-40 TITLE: Case Hardening Ferrous Materials REVISION: 1508 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Co
19、rporate Technical Standards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. AUGUST 2015 Page 3 of 8 A5.4 Microstructure Surface and near surface microstructures are important to performance. A structure of tempered martensite and retained austenite which results in a s
20、urface hardness of not less than 57 HRC or the minimum specified on the drawing is required. Exceptions are noted below. (Note that retention of a sharp edge on the metallographic section is very important for determination of surface microstructures. Use of electroless nickel plating of the case ha
21、rdened surface is suggested for edge retention.) TABLE II CLASSIFICATION (1) AND REQUIREMENTS (2) Heavy Cases Navistar Class(4) Effective Case Depth(3) Navistar Class(4) Effective Case Depth(3) inch mm inch mm 25 0.018-0.038 0.40-0.90 60 0.048-0.074 1.25-1.90 30 0.022-0.043 0.50-1.00 70 0.056-0.082
22、1.50-2.15 35 0.026-0.048 0.65-1.25 80 0.065-0.095 1.65-2.40 40 0.031-0.055 0.75-1.40 90 0.075-0.105 1.90-2.65 45 0.036-0.060 0.90-1.50 110 0.095-0.125 2.40-3.15 50 0.040-0.066 1.00-1.65 130 0.115-0.145 2.90-3.65 (1) Where deemed feasible on particular parts and after consultation with Materials Engi
23、neering, more than one Class may be specified. See “Appendix” for further discussion. (2) All case-hardened steels shall be produced using fully-killed, fine-grain practices. (3) Case depth measurements on gear teeth will be made at the pitch line and at the root fillet. At the pitch line, the case
24、depth will conform to the specified class; at the root fillet, it will be not less than 50% of the minimum specified class. On critical parts, it is desirable to specify the location for case depth checks since the case depth may vary from one area to another on a single part. (4) For obsolete parts
25、 with conventional (total) case depth specified on the engineering drawing, the relationships between effective and conventional case depths are approximate. Contact Materials Engineering for conversion of the obsolete case depth to one of the Navistar Classes shown in Table II. A5.4.1 Only well-dis
26、tributed globular carbides are permitted. A5.4.2 Limited amounts of intergranular oxides or associated transformation products are allowed, but to a depth no greater than 0.001 inch (25m). Where performance requires no intergranular oxides or associated transformation products, a note about it shoul
27、d be put on the parts drawing. A5.4.3 While bainite in the case is not desired, a small amount is permissible providing the minimum surface hardness of 57 HRC is maintained. A5.5 Measurement of Case Properties A5.5.1 Location of Measurement Measurement will be made on a suitably polished cross secti
28、on, perpendicular to the one or more significant surface on the finished part, after all grinding has been performed. Case depth measurements NUMBER: MPAPS A-40 TITLE: Case Hardening Ferrous Materials REVISION: 1508 This document is restricted and may not be sent outside Navistar, Inc. or reproduced
29、 without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. AUGUST 2015 Page 4 of 8 on gear teeth will be made at two locations: (1) the pitch line, and (2) the root fillet, both on a plane midway between the ends of the tooth
30、. Due to the difficulty of locating the theoretical pitch line, this position will be considered to be approximately midway between the tip and the root, on a line perpendicular to a line tangent to the surface, as shown in the following figure. A6.0 METHODS OF TEST A6.1 Methods of Measurement A6.1.
31、1 Total Case Depth (TCD) TCD should be measured on an etched section at a magnification of 100 diameters using a micrometer ocular calibrated to read in thousandths of an inch (hundredths of a mm), or other suitable device, recording average depth to core structure. A6.1.2 Effective Case Depth of Ca
32、rburizing A6.1.2.1Effective case depth (ECD) is a vertical distance from surface (edge of a cross section) where the hardness reaches the value 50 HRC. To establish ECD make a series of microhardness impressions across the case on a polished and unetched section perpendicular to the significant surf
33、ace, using a properly calibrated microhardness tester with a Vickers or Knoop penetrator (ASTM E384). Space the microhardness impressions so that they are not distorted by adjacent impressions or by the surface. Using loads of 500 or 1000 grams force, spacing of 0.005 inch (0.13 mm) have been found
34、satisfactory. Closer spacing may be obtained, if necessary, by two or more traverses of impressions at staggered distances from the surface. A6.1.2.2 When the desired traverse has been completed, convert hardness readings to the nearest whole number of the Rockwell C scale using the conversions list
35、ed in ASTM E140. Plot the hardness values against their depth from the surface and draw a curve approximately connecting the points. Determine the depth at which the curve crosses the Rockwell 50 HRC hardness level. This is effective case depth. A6.1.3 Other Methods of Case Depth Measurement For pro
36、duction control, it may be necessary to use other methods for measuring case depth, at the discretion of the producer. However, it is the producers responsibility to establish correlation between the method employed and the methods specified above. Since this specification refers only to case depth
37、of finished parts, it may be necessary to produce cases deeper than those specified herein to compensate for stock removed during grinding or other manufacturing processes. A6.1.4 Core Hardness When control over core hardness is required, the hardness range and test location shall be specified on th
38、e engineering drawing. For gear applications, core hardness shall be measured at the root diameter, mid-tooth thickness, and mid face width. NUMBER: MPAPS A-40 TITLE: Case Hardening Ferrous Materials REVISION: 1508 This document is restricted and may not be sent outside Navistar, Inc. or reproduced
39、without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2015 by Navistar, Inc. AUGUST 2015 Page 5 of 8 B. NITRIDING and FERRITIC NITROCARBURIZING The following sections, prefixed with a (B), apply to nitride and ferritic nitrocarburized component
40、s only. B4.0 CLASSIFICATION Parts will be identified on the engineering drawing as Nitrided or Ferritic Nitrocarburized. B5.0 GENERAL REQUIREMENTS B5.1 Microstructure Unless otherwise specified, the white layer on nitrided and ferritic nitrocarburized components will be limited to 20m maximum. Poros
41、ity in the white layer shall not extend beyond one-half of the total white layer depth as observed by metallographic examination at 1000X. B5.2 Surface Hardness Unless otherwise specified, surface hardness requirements shall be as shown in Table IV. TABLE IV SURFACE HARDNESS REQUIREMENTS FOR NITRIDE
42、D and FERRITIC NITROCARBURIZED STEEL Material Condition of Material Core Hardness, Rockwell HRC, min Superficial Hardness of Surface, Rockwell HR15N, min Plain Carbon and Alloy Steels As-Rolled or As-Cast C0.15% - 67 C 0.15 % - 73 Quenched and Tempered* 23 25 28 30 75 77 78 81 * The minimum temperin
43、g temperature shall be at least 30C (50F) higher than the maximum temperature used in nitriding or nitrocarburizing B6.0 METHODS OF TEST B6.1 Case Depth. The case depth requirement as well as the measurement method should be specified on the engineering drawing. Unless otherwise specified, case dept
44、h requirements are considered minimums. NUMBER: MPAPS A-40 TITLE: Case Hardening Ferrous Materials REVISION: 1508 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent li
45、ability. 2015 by Navistar, Inc. AUGUST 2015 Page 6 of 8 B6.1.1 Total Case Depth (TCD) Total Case Depth is the average depth from the surface to core structure when evaluated on an etched cross section at a magnification of 100 diameters. B6.1.2 Effective case depth (ECD) B6.1.2.1Effective Case Depth
46、 is defined as the depth from the surface to the point where the hardness reaches a value of (core hardness) +50 HV B6.1.2.2 For gear applications, the Effective Case Depth shall be used. ECD measurements shall be taken at the pitch line as shown in Section A5.5.1 B6.1.3 Core hardness Core hardness
47、shall be measured at a depth of 3x the total case depth unless otherwise specified. The quench and temper and core hardness requirements shall be specified on the engineering drawing. 7.0 QUALITY All product supplied shall be clean and free from dirt, oils, sharp edges, or defects harmful to product
48、 performance. The supplier should be capable of providing statistical evidence that the product has been manufactured within established process control limits for the product and that the process is capable of meeting all specification requirements. 7.1 Quality Control Plan A Quality Control Plan f
49、or products supplied to the requirements of this specification will be established by mutual agreement between NAVISTAR and the supplier. 8.0 SOURCE APPROVAL AND QUALITY CONTROL 8.1 Supplier Requirements All suppliers to NAVISTAR are required to be registered to ISO 9001 Quality System Requirements. NAVISTAR will also accept TS-16949 registration as long as the supplier can also fulfill all AIAG PPAP (Production Part Approval Process) documentati
