SAE J 423-1998 Methods of Measuring Case Depth《测量表面硬化深度方法》.pdf

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1、SAE-J423ADOPTION NOTICESAE-J423, “CASE DEPTH, METHODS OF MEASURING“, was adopted on27-JAN-95 for use by the Department of Defense (DoD). Proposedchanges by DoD activities must be submitted to the DoD AdoptingActivity: Commander, Atlantic Division, Naval FacilitiesEngineering Command, Criteria Office

2、, 1510 Gilbert St, Norfolk,VA 23511-2699. Copies of this document may be purchased fromthe Society of Automotive Engineers 400 Commonwealth DriveWarrendale, Pennsylvania, United States, 15096-0001. http:/www.sae.org/_Custodians: Adopting Activity:Navy - YDArmy - MRNavy - YDAir Force - 11Reviewer Act

3、ivities:Navy - ASAREA NDTIDISTRIBUTION STATEMENT A: Approved for public release; distributionis unlimited.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE Technical Standards Board Rules provide tha

4、t: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.”SAE

5、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.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-8512 FAX: (724) 776-0243TO PLACE A DOCUMENT ORDER; (724) 776-4970 FAX: (724) 776-0790SAE W

6、EB ADDRESS http:/www.sae.orgCopyright 1998 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICEAn American National StandardJ423REAF.FEB1998Issued 1950-01Reaffirmed 1998-02Superseding J423 DEC83M

7、ethods of Measuring Case DepthForewordThis Document has not changed other than to put it into the new SAE Technical Standards BoardFormat. References were added as Section 2. Definitions were changed to Section 3. All other section numbershave changed accordingly. 1. ScopeCase hardening may be defin

8、ed as a process for hardening a ferrous material in such a manner thatthe surface layer, known as the case, is substantially harder than the remaining material, known as the core.The process embraces carburizing, nitriding, carbonitriding, cyaniding, induction, and flame hardening. Inevery instance,

9、 chemical composition, mechanical properties, or both are affected by such practice.This testing procedure describes various methods for measuring the depth to which change has been made ineither chemical composition or mechanical properties. Each procedure has its own area of applicationestablished

10、 through proved practice, and no single method is advocated for all purposes.Methods employed for determining the depth of case are either chemical, mechanical, or visual, and thespecimens or parts may be subjected to the described test either in the soft or hardened condition. Themeasured case dept

11、h may then be reported as either effective or total case depth on hardened specimens,and as total case depth on unhardened specimens.It should be recognized that the relationship between case depths as determined by the different methods canvary extensively. Factors affecting this relationship inclu

12、de case characteristics, parent steel composition,quenching conditions, and others. It is not possible to predict, in some instances for example, effective casedepth by chemical or visual means. It is important, therefore, that the method of case depth determination becarefully selected on the basis

13、 of specific requirements, consistent with economy.2. References2.1 Applicable PublicationThe following publication forms a part of the specification to the extent specifiedherein. Unless otherwise indicated the latest revision of SAE publications shall apply.2.1.1 ASM INTERNATIONAL PUBLICATIONAvail

14、able from: ATTN: MSC/Book Order, ASM International, PO Box473, Novelty, OH 44072-9901.“The Application of MsPoints to Case Depth Measurement,“ by E. S. Rowland and S. R. Lyle, ASMTransactions, Vol. 37 (1946) pp. 2647.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo

15、reproduction or networking permitted without license from IHS-,-SAE J423 Reaffirmed FEB1998-2-3. Definitions3.1 Effective Case DepthThe perpendicular distance from the surface of a hardened case to the furthest pointwhere a specified level of hardness is maintained. The hardness criterion is 50 HRC

16、normally, but see Table 1under 5.1.Effective case depth should always be determined on the part itself, or on samples or specimens having aheat-treated condition representative of the part under consideration.3.2 Total Case DepthThe distance (measured perpendicularly) from the surface of the hardene

17、d or unhardenedcase to a point where differences in chemical or physical properties of the case and core no longer can bedistinguished.4. Chemical Methods4.1 GeneralThis method is generally applicable only to carburized cases, but may be used for cyanided orcarbonitrided cases. The procedure consist

18、s in determining the carbon content (and nitrogen when applicable)at various depths below the surface of a test specimen. This method is considered the most accurate formeasuring total case depth on carburized cases.4.2 Procedure for Carburized CasesTest specimens shall normally be of the same grade

19、 of steel as partsbeing carburized. Test specimens may be actual parts, rings, or bars and should be straight or otherwisesuitable for accurate machining of surface layers into chips for subsequent carbon analysis.Test specimens shall be carburized with parts or in a manner representative of the pro

20、cedure to be used forparts in question. Care should be exercised to avoid distortion and decarburization in cooling test specimensafter carburizing. In cases where parts and test specimens are quenched after carburizing, such specimensshould be tempered at approximately 600 to 650 C (1100 to 1200 F)

21、 and straightened to 0.04 mm (0.0015 in)max total indicator reading (TIR) before machining is attempted. The time at temperature should be minimizedto avoid excessive carbon diffusion.Test specimens must have clean surfaces and shall be machined dry in increments of predetermined depth.The analysis

22、of machined chips will then accurately reveal the depth of carbon penetration. Chosenincrements usually vary between 0.05 and 0.25 mm (0.002 and 0.010 in) depending upon the accuracy desiredand expected depth of case.Chips from each increment shall be kept separate and analyzed individually for carb

23、on content by an acceptedmethod. Total case depth is considered to be the distance from the surface equivalent to the depth of the lastincrement of machining whose chips analyze to a carbon content 0.04% higher than that of the establishedcarbon content of the core.Specialized electron microprobe an

24、alyses on carefully prepared cross-sections represent an alternateprocedure with potentially greater accuracy and speed, and is recommended when equipment is available.5. Mechanical Methods5.1 GeneralThis method is considered to be one of the most useful and accurate of the case depth measuringmetho

25、ds. It can be effectively used on all types of hardened cases, and is the preferred method fordetermination of effective case depth. The use of this method requires the obtaining and recording ofhardness values at known intervals through the case. For determination of effective case depth, the 50 HR

26、Ccriterion is generally used. The sample or part is considered to be through hardened when the hardness leveldoes not drop below the effective case depth hardness value. In some instances involving flame and inductionhardened cases, it is desirable to use a lower hardness criterion. Suggested hardne

27、ss levels are tabulated inTable 1 for various nominal carbon levels.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J423 Reaffirmed FEB1998-3-A plot of hardness versus depth from the surface will f

28、acilitate this reading. Figures 1, 2, 3, and 4 illustrate therecommended procedures. Hardness testers which produce small, shallow impressions should be used for all of the following procedures,in order that the hardness values obtained will be representative of the surface or area being tested. Tho

29、setesters which are used to produce Diamond Pyramid or Knoop Hardness Numbers are recommended,although testers using heavier loads, such as the Rockwell superficial, A or C scales, can be used in someinstances on flame and induction hardened cases.Considerable care should be exercised during prepara

30、tion of samples for case depth determination by any ofthe mechanical methods, to insure against grinding or cutting burn. The use of an etchant for burn detection isrecommended as a general precaution, because of the serious error which can be introduced by its presence.FIGURE 1SPECIMEN FOR TAPER GR

31、IND PROCEDUREFIGURE 2SPECIMEN FOR CROSS SECTION PROCEDUREFIGURE 3SPECIMEN FOR ALTERNATE CROSS SECTION PROCEDUREFIGURE 4SPECIMEN FOR STEP GRIND PROCEDURETABLE 1CARBON CONTENTCarbon ContentEffective CaseDepth Hardness0.280.32% C 35 HRC0.330.42% C 40 HRC0.430.52% C 45 HRC0.53% and over 50 HRCCopyright

32、SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-SAE J423 Reaffirmed FEB1998-4-5.2 Hardness Traverse ProcedureCut specimens perpendicular to hardened surface at critical location beingcareful to avoid any cutting

33、 or grinding practice which would affect the original hardness.Grind and polish specimen. Surface finish of the area to be traversed shall be polished finely enough so thehardness impressions are unaffectedthat is, the lighter the indentor load, the finer the polish necessary.The procedure illustrat

34、ed by Figure 2 is recommended for the measurement of light and medium cases. Thealternate procedure illustrated in Figure 3 is recommended for medium and heavier cases.The hardness traverse should be started far enough below the surface to ensure proper support from the metalbetween the center of th

35、e impression and the surface. Subsequent impressions are spaced far enough apartso as not to distort hardness values. The distance from the surface of the case to the center of the impressionis measured on a calibrated optical instrument, micrometer stage, or other suitable means.5.3 Taper Grind Pro

36、cedureThis procedure, illustrated by Figure 1, is recommended for measurement of lightand medium cases.A shallow taper is ground through the case, and hardness measurements are made along the surface thusprepared. The angle is chosen so that readings, spaced equal distances apart, will represent the

37、 hardness atthe desired increments below the surface of the case.Unless special anvils are used, a parallel section should be prepared so that readings are taken at right anglesto the surface. Care should be exercised in grinding to prevent tempering or rehardening.5.4 Step Grind ProcedureThis proce

38、dure illustrated by Figure 4 is recommended for measurement of mediumand heavy cases.It is essentially the same as the taper grind section method with the exception that hardness readings aremade on steps which are known distances below the surface.A variation in this procedure is the step grind met

39、hod where two predetermined depths are ground to insurethat the effective case depth is within specified limits.6. Visual Methods6.1 GeneralThis method employs any visual procedure with or without the aid of magnification for reading thedepth of case produced by any of the various processes. Samples

40、 may be prepared by combinations offracturing, cutting, grinding, and polishing methods. Etching with a suitable reagent is normally required toproduce a contrast between the case and core. Nital (concentrated nitric acid in alcohol) of various strengths isfrequently used for this purpose.6.2 Macros

41、copicMagnification methods for determination of case depth measurement are recommended forroutine process control, primarily because of the short time required for determinations, and the minimum ofspecialized equipment and trained personnel needed. They have the added advantage of being applicable

42、tothe measurement of all types of cases. However, the accuracy can be improved by correlation with othermethods more in keeping with engineering specifications for the parts being processed. These methods areapplied normally to hardened specimens, and while a variety of etchants may be employed with

43、 equal success,the following procedures are typical and widely used.6.2.1 FRACTUREPrepare product or sample by fracturing. Examine at a magnification not to exceed20diameters with no further preparation.Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction o

44、r networking permitted without license from IHS-,-SAE J423 Reaffirmed FEB1998-5-6.2.2 FRACTURE AND ETCHWater quench product or samples directly from the carburizing temperature. Fractureand etch in 20% nitric acid in water for a time established to develop maximum contrast. Rinse in water andread wh

45、ile wet.6.2.3 FRACTURE OR CUT, AND ROUGH GRINDPrepare specimen by either fracturing, or cutting and rough grinding.Etch in 10% nital for a period of time established to provide a sharp line of demarcation between case andcore. Examine at magnification not to exceed 20 diameters (Brinell glass) and r

46、ead all the darkened area forapproximate total case depth.6.2.4 FRACTURE OR CUT, AND POLISH OR GRINDPrepare specimen by fracturing or cutting. Polish or grindthrough No. 000 or finer metallographic emery paper or both. Etch in 5% nital for approximately 1 min.Rinse in two clean alcohol or water rins

47、es. Examine at magnification not to exceed 20 diameters (Brinellglass) and read all of the darkened zone. After correlation, effective case depth can be determined byreading from external surface of specimen to a selected line of the darkened zone.6.3 MicroscopicMicroscopic methods are generally for

48、 laboratory determination and require a completemetallographic polish and an etch suitable for the material and the process. The examination is made mostcommonly at 100 diameters.6.3.1 CARBURIZED CASESThe microscopic method may be used for laboratory determinations of total case andeffective case de

49、pths in the hardened condition. When the specimen is annealed properly, the total casedepth and the depth of the various zoneshypereutectoid, eutectoid, and hypoeutectoidalso can bedetermined quite precisely.1a. Hardened Condition1. Fracture or cut specimen at right angles to the surface.2. Prepare specimen for microscope and etch in 2 to 5% nital (concentrated nitric acid in alcohol).3. For effective case depth, read from surface to metallographic str