NAVISTAR MPAPS G-19 PART II-2014 Electrodeposited Engineering (Hard) Chromium Coatings.pdf
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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. 2014 by Navistar, Inc. DECEMBER 2014 Page 1 of 6 NAVISTAR, INC. Material, Parts, and Process Specificatio
2、ns (MPAPS) NUMBER: MPAPS G-19 Part II Former Designation: CEMS G-19 Part II TITLE: : Electrodeposited Engineering (Hard) Chromium Coatings CURRENT REV No.: 1412 DATE: Dec. 2014 WRITTEN/EDITED BY: Materials Engineering APPROVED BY: Materials Engineering SUPERSEDES: CEMS G-19 Pt II April 2002 PRINTED
3、COPIES OF THIS DOCUMENT MUST BE VERIFIED 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 heal
4、th practices and to determine the applicability of regulatory limits prior to use. Change Notice: Changed to new MPAPS spec format; extensive revision, editorial changes. 1.0 APPLICATION 1.1 Engineering coatings of chrome plate are generally used to increase the surface hardness of a part or to impr
5、ove its wear resistance 1.2 Chromium plate is hard and dense with good corrosion resistance to most materials. It has a lower friction coefficient than any other metal and good anti-galling properties as long as it is not used against itself. Despite its hardness, it should not be used as a general
6、substitute for hardening but only when properly engineered for this purpose. It may be applied to aluminum, copper, steel and cast iron substrates. 1.3 Hard chromium, as differentiated from decorative chromium, is applied for functional reasons regardless of thickness. If a 0.00005 inch (1.3 m) depo
7、sit is applied to a surface, its apparent hardness will reflect that of the basis metal. If, however, a 0.0015-.0020 inch (38-51 m) deposit is applied over an unhardened part, it will be hard. In short, a deposit of over 0.001 inch (25 m) is essential before chromium will assume its true hardness ch
8、aracteristics when applied to unhardened basis metals, whereas over a hardened base, this thickness is not necessary because of the substantial backing provided. 2.0 SCOPE This specification covers the basic requirements for electrodeposited hard chromium as used to meet service conditions involving
9、 wear, corrosion, friction or a combination of these. 2.1 Restricted Chemical Substances Effective 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, th
10、e latest issue of all referenced standards shall apply. The following Specifications, Standards, and Regulations are referenced in this specification. Quality System Standard ISO 9001 or TS-16949 ASTM B177 ASTM B499 NAVISTAR Engineering Design Std A-16 ASTM B117 ASTM B504 NAVISTAR Manufacturing Std.
11、 MS-D-13 ASTM B456 ASTM E384 NAVISTAR MPAPS B-50 ASTM B487 ASTM B650 CFR Title 29, Part 1910 ASTM B242 ASTM B183 ASTM B322 ASTM B253 ASTM B281 NUMBER: MPAPS G-19 Part II TITLE: Electrodeposited Engineering (Hard) Chrome Coatings REVISION: 1412 This document is restricted and may not be sent outside
12、Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Suppliers are required to assume all patent liability. 2014 by Navistar, Inc. DECEMBER 2014 Page 2 of 6 ASTM B242 ASTM B254 ASTM B320 ASTM B578 ASTM B571 ASTM B849 ASTM F519 ASTM B850 ASTM B851 4.0 REQUIREMENTS Three
13、 classes of plating for engineering applications are provided for in this specification as shown in the table below: Class Resistance to Typical Applications Chromium Thickness * Adhesion Test Porosity Test wear corrosion mils m DS excellent good Pump shafts, Hyd. Piston rods 1.00 min 25 min Pass Pa
14、ss 1.50 avg 38 avg ES good good Hyd. Piston rods 0.40 to 0.80 10 to 20 Pass Pass FS Fair Fair Air valves 0.25 min 6 min Pass Not required 0.35 avg 9 avg *Production parts, when required, will be produced undersize to allow for the plating thickness shown in above table. They will then be plated to m
15、eet specified size requirements. 4.1 Surface Preparation 4.1.1 Cleaning The articles to be plated will be thoroughly cleaned and free from rust, scale, oil and other foreign matter detrimental to the final finish as recommended in ASTM B177. The surface will have a sufficiently fine finish to assure
16、 the desired final plating quality. Parts to be electroplated may be cleaned in accordance with ASTM Practices B183, B254, B242, B281, B320, B322, B481, B558 or B630 or Guide B253. 4.1.2 Hydrogen Embrittlement The cleaning on ferrous operation will be controlled to prevent hydrogen embrittlement, es
17、pecially in those parts that are hardened, cold worked or subject to high service stresses. 4.1.3 Stress Relief High strength/high hardness steel parts that are subjected to machining, grinding, cold forming or cold straightening after heat treatment are particularly susceptible to hydrogen absorpti
18、on. Therefor such parts should be stress relieved prior to cleaning and plating per ASTM B849. 4.1.4 Shot Peening Parts for which fatigue life after plating will benefit from compressive residual surface stresses may be shot peened per ASTM B851. 4.2 Thickness The thickness of plating is shown in th
19、e table above. Measurements will be made on significant surfaces. These are defined as those that can be touched with a 0.75 inch (19 mm) diameter ball. This definition may be superseded by notations on the engineering drawing. 4.3 Hardness The hardness of the plating will be 800 VHN minimum. As a r
20、outine check, engineering chromium should be file hard. NUMBER: MPAPS G-19 Part II TITLE: Electrodeposited Engineering (Hard) Chrome Coatings REVISION: 1412 This document is restricted and may not be sent outside Navistar, Inc. or reproduced without permission from Corporate Technical Standards. Sup
21、pliers are required to assume all patent liability. 2014 by Navistar, Inc. DECEMBER 2014 Page 3 of 6 4.4 Adhesion The coating will be sufficiently adherent to the basis metal to pass an adhesion test appropriate to the subject part selected from methods described in paragraph 5.1.3 below. 4.5 Porosi
22、ty The coating will meet the requirement for porosity when tested by one of the methods specified in paragraph 5.1.4. When no special porosity requirement is specified by the purchaser, maximum porosity will be 6 spots per 12 in2 (77.5 cm2) or 2 spots in any square inch (6.5 cm2) of significant surf
23、ace. No pore will be larger than 0.04 inches (1.0 mm) in diameter. 5.0 QUALITY The plate will be hard, smooth, adherent and plated in the bright range. Normally, the appearance of the engineering plate is secondary; however, when a particular finish is desired it will be agreed upon between the supp
24、lier and purchaser. 5.1 Methods of Test 5.1.1 Hardness The Vickers hardness number (VHN) will be determined according to ASTM B578 and ASTM method E384. Where possible the loading selected will not produce an impression with a diagonal longer than 67% of the thickness of the chromium layer. The hard
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