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1、I 2000FTM3 O I Comparison of New Gear Metallurgy Documents, IS0 6336-5 and AGMA 923 with Gear Rating Standards AGMA 2001 and 2003 by: A.A. Swiglo, IIT Research Institute American Gear Manufacturers Association TECHNICAL PAPER Copyright American Gear Manufacturers Association Provided by IHS under li
2、cense with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 02:40:19 MDTNo reproduction or networking permitted without license from IHS -,-,- O Comparison of New Gear Metallurgy Documents, IS0 6336-5 and AGMA 923 with Gear Rating Standards AGMA 2001 and 2003 A. A
3、lan Swiglo, IIT Research Institute The statements and opinions contained herein are those of the author and should not be construed as an official action or opinion of the American Gear Manufacturers Association. Abstract This paper will compare and contrast two newly revised documents. IS0 6336-5 a
4、nd AGUA 923, with two that are familiar to todays gear producers -AGMA 2001 and 2003. These new documents were prepared on a consensus basis for big gears, little gears, high production, one-of-a-kind gears, and everything in between. A short history of the long evolution and the logic behind the ne
5、w documents ispresented. This paper discusses whats new, whats different, whats clarified, whats the same, and whats hidden in the footnotes. The observations are presented from the viewpoint of a gear metallurgistbeat treater - one who has a long and active record of participation in the preparatio
6、n of these documents. Knowing the differences will be important to the users of these new documents. Weil thought out practical consistency was the goal. Was it accomplished? This paper recommends working according to the requirements and recommendations of the new documents. The ultimate goal of th
7、is paper is to get the questions and feedback known to the preparen of the next generation of documents, so that there will be more consistency between the documents the next time. Copyright O 2000 American Gear Manufacturers Association 1500 King Street, Suite 201 Alexandria, Virginia, 22314 Octobe
8、r, 2000 ISBN: 1-55589-764-9 Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 02:40:19 MDTNo reproduction or networking permitted without license from IHS -,-,- Contents * Page Sco
9、pe Introduction 1 2.1 - Basic assumptions . 1 2.2 - Inclusions and exclusions . 2 2.3 - Cautions 2 References . 3 Purpose . 3 Conventions . 4 Metallurgical topic discussed . 5 General changes in AGMA 923 . 5 Specific comparisons 6 Conclusions and recommendations 109 Whats next? 109 Acknowledgements
10、. 110 I 2 3 4 5 6 7 8 9 10 11 1 2 3 4 e 5 10 I 1 12 13 14 15 16 Chemistry 7 Grain size . 10 Hardenability 12 Non-metallic inclusions 14 Material (no table) 5.1 - Form 22 5.2 - Reduction ratio (wrought only) . 24 Heat treatment (prior to any case or surface hardening) 26 Mechanical properties after h
11、eat treatment prior to any case or Surface hardening 28 Microstructure prior to any case or surface hardening . 31 Ultrasonic inspection (no table) 9a -Wrought material - Flat bottom hole (FBH) technique 36 9b - Wrought material - Back reflection technique) . 40 9c - Castings - Back reflection techn
12、ique 44 Overheating, especially at the tooth tips and end faces . 47 Tempering after case or surface hardening . 48 Surface hardness . 49 Case depth - General . 52 13.1 - Effective (on flank) 55 13.2 - Effective at root radius 57 13.3 - Total 59 Core (Base) hardness after any case or surface hardeni
13、ng 60 Surface carbon . 62 Surface microstructure - General . 64 16.1 - Intergranular oxidation (IGO) . 66 16.2 - Non-martensitic transformation products 68 16.3 - Decarburization 70 i Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/111
14、1111001, User=Wing, Bernie Not for Resale, 04/18/2007 02:40:19 MDTNo reproduction or networking permitted without license from IHS -,-,- Con tents (continued) Page 16.4 . Epsilon nitride (white layer) . 75 17 Case microstructure - General 77 17.1 - Carbide precipitation . 79 17.2 - Retained austenit
15、e 81 17.3 - Near surface above the root (along flank) . 83 17.4 - Mid case above the root (along flank) . 85 17.5 - Near surface at the root 87 17.6 - Mid case at the root 89 17.7 - Microcracks 91 18 Core microstructure 92 19 Heat affected zone 94 20 Surface temper etch inspection of ground teeth 95
16、 21 Surface cracks 97 22 Magnetic particle inspection of finished gearing 100 23 Shot peening 107 Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie Not for Resale, 04/18/2007 02:40:19 MDTNo reproduction or n
17、etworking permitted without license from IHS -,-,- 1 Scope This paper compares the requirements and recommendations of four documents (AGMA 923, AGMA 2001, AGMA 2003 and IS0 6336- 5). AGMA 923 and IS0 6336-5 are works-in- progress in the final stages of development but are not yet approved AGMA or I
18、S0 documents. This paper shares some of the history and logic that went into the creation of these documents and highlights the nuances of meaning between the various terminologies that are used. In order to make comparisons easier, this paper rearranged the requirements from the various referenced
19、documents in a manner such that each table covers a single metallurgical topic and includes all of the requirements for that topic regardless of the heat-treat method. The exact wording from each of the referenced documents is copied in that table and is annotated with comments from the author. This
20、 paper also highlights the authors opinions as to what are the significant comparisons between the docu- ments, especially between AGMA 923 and IS0 6336-5. 2 Introduction Once upon a time, AGMA rating standards gave ranges for its ratings with a statement implying that good metallurgy entitled the u
21、ser to use higher allowable stresses. This begged the question of, “What is good metallurgy?“ After much discussion, the proposals included those that observed that good metallurgy was related to the salary of the chief metallurgist and the length of the specifications referenced on the gear drawing
22、. Since those proposals, while somewhat true, were not practical or acceptable as a national standard, a good brainstorming session ultimately resulted in a collection of metallurgical factors that were listed in sequence of percieved decreasing. importance. This col-lection of factors ultimately wa
23、s included in ANSIIAGMA 6033-A88, Standard for Marine Propulsion Gear Units, Part I, Materials and ANSIIAGMA 2001-888, Fundamental Rating Factors and Calculation Methods for Involute Spur and Helical Gear Teeth. The forewords of the referenced documents contain a more detailed history of the various
24、 documents The three /SO 6336-5 material quality grades, ML, MQ and ME, stand in relationship to the diagrams of that document that refer to allowable stress numbers. IS0 6336-5 gives the following meaning for its grade designations. ML stands for modest demands on the material quality and on the ma
25、terial heat treatment process during gear manufacture. MQ stands for requirements that can be met by experienced manufacturers at moderate cost. ME represents requirements that must be realized when a high degree of operating reliability is required. The referenced AGMA documents do not have a paral
26、lel explanation for its grade designations Note that for through hardened gearing, IS0 Grade MQ is similar in allowable stress ratings to AGMA Grade 1, and IS0 Grade ME is similar in allowable stress ratings to AGMA Grade 2. 2.1 Basic assumptions This paper does not in any way replace the referenced
27、 standards. The knowledge and judgement required to eval- uate the items discussed in this paper and the referenced documents comes from years of accumulated experience in gear design, gear manufacturing, and gear metallurgy. These documents are not intended for use by the engineering public at larg
28、e. Those not meeting the stated requirements should be cautious and seek the advice and counsel of those meeting the requirements. All of the referenced documents require that all criteria in any given grade must be met in order to qualify for use of the stress number allowable for that grade. There
29、 is no partial credit in these gear rating standards for meeting or exceeding some, but not all, of the criteria. The careful user of the referenced standards will find that 1 Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001,
30、 User=Wing, Bernie Not for Resale, 04/18/2007 02:40:19 MDTNo reproduction or networking permitted without license from IHS -,-,- documented experience and good engineering, whatever that is, permits use of allowable stresses other than those given in the refer- enced standards. All of the referenced
31、 documents have provisions such that unless otherwise specified, proper process control, with periodic verification, is an acceptable method to meet the requirements of that document. It should also be noted that all of the referenced documents are consensus-based documents. As such they rely on the
32、 experience and expertise of all those who participate in creating the documents. Unanimous agreement is not necessary. Only substantial agreement is nec- essary. Individual and special cases are not included. Actual test data in suppo.rt of detailed information is not required for admission into th
33、ese documents. 2.2 Inclusions and exclusions AGMA 923 and the referenced documents address only the tooth areas of gearing, but not the other features such as shafts, bearing sur- faces, splines, keyways, hubs, and webs. AGMA 923 unlike /SO 6336-5 does not discuss allowable stress numbers or case de
34、pth specifi- cations. These topics are considered by AGMA to be within the domain of the ratings com- mittees. Carbonitriding, nitrocarburizing and cast pinions are not covered by any of the referenced documents. The only exception being that IS0 6336-5 does cover nitrocarburizing. The surface harde
35、ned (SH) Grade 3 applies only to induction hardening with Type A (contour) pattem. Note that AGMA 6002 includes allow- able stresses for SH Grade 3 but AGMA 2001 and 2003 do not. 2.3 Cautions Meeting the requirements of one or more of the referenced documents does not imply that the requirements of
36、any of the other referenced documents are met. This is especially true between the AGMA and IS0 documents, including the versions that will soon be published. There are three areas of microstructural concern in AGMA 923 core. surface (the first 0.002 - 0.003 inch), case (which includes the surface),
37、and Note that not all of the referenced documents use the same definitions of these terms. The user of the referenced documents must also clearly understand the definitions and nuances of meaning of related terms, especially: Required, recommended, Capable of, certified, Case hardness, surface hardn
38、ess, Process control coupon, representative Surface, case, and core, Non-martensitic structures, non-marten- sitic transformation products, Case hardening, surface hardening, and Methods, alternatives When interpreting specifications, especially IS0 6336-5, and test results, it is extremely importan
39、t to understand and agree upon the use of certain terminology such as: case and surface hardness, effective and total case depth, and which hardness criteria is used for defining effective case depth. Some of the requirements and recommend- ations of the referenced documents apply only to the pittin
40、g (contact) resistance rating while others apply only to the bending strength rating. The flank area of a gear tooth and the root area of the gear tooth can have different metallurgical requirements and recommendations. The notes shown on each table of this document are important to the understandin
41、g of that table. Pay particular attention to notes in the mini-table of characteristics (factors) and in the table column headers. Also, pay attention to the location in a table of the reference to a note. It tells whether that specific note applies to all characteristics, all grades for that charac
42、teristic, only that grade, or perhaps only a portion of the requirement or recommendation for that grade. Effective case depth, total case depth, coupon, 2 Copyright American Gear Manufacturers Association Provided by IHS under license with AGMA Licensee=IHS Employees/1111111001, User=Wing, Bernie N
43、ot for Resale, 04/18/2007 02:40:19 MDTNo reproduction or networking permitted without license from IHS -,-,- Pay attention to the borders of the individual cells within the various tables. They indicate grou pings of requirements. WARNING - A little bit of knowledge is a dangerous thing. Errors have
44、 intentionally been introduced and/or left in this document to demonstrate the authors fallibility and to force the reader to think critically, becoming intimately familiar with the reference documents. Please report the errors you find to the author so that he can correct them and possibly insert r
45、eplacements. 3 References AGMA 923-AXX (6/00 Committee Comment Draft after Comment Resolution Meeting 8/9- 1 O/OO), Metallurgical Specifications for Steel Gearing. This is a work-in-progress and is not yet an approved AGMA Information Sheet. ANSIIAGMA 2001-888, Fundamental Rating Factors and Calcula
46、tion Methods for Involute Spur and Helical Gear Teeth. ANSIIAGMA 2003-897 Rating the Pitting Resistance and Bending Strength of Generated Straight Bevel, Zero1 Bevel and Spiral Bevel Gear Teeth. ANWAGMA 6002-B93, Design Guide for Vehicle Spur and Helical Gears. ANSIIAGMA 6033-A88, Standard for Marin
47、e Propulsion Gear Units, Pari I, Materials. ASTM E140-97, Hardness conversion tables for Metals (Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Knoop Hardness and Scleroscope Hardness. IS0 6336-51996, Calculation of load capacity of spur and helical gears - Pari 5 : Streng
48、th and quality of materials. IS0 6336-5 (committee Draft after 11/99 Resolution Meeting), Calculation of load capacity of spur and helical gears - Part 5: Strength and quality of materials. This also is a work-in-progress and is not yet an approved IS0 document. 4 Purpose During the creation of AGMA
49、 923 the author and those others involved in its creation have attempted to accomplish the worthy goals that follow. 0 Consolidate in one place a standardized set of metallurgical requirements applicable for all types of gearing. Minimize the games of “Can you find the differences in the referenced documents?“ and “Can