1、ICS 25.200Wrmebehandlung von Eisenwerkstoffen Verfahren der Wrmebehandlung Teil 5: RandschichthrtenIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.ContentsPageForeword . . . . .
2、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3、. . . . 12 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4、. . . . . . . . . 24 Principle of method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Identification of heat treatment condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5、 . . . . 26 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.1 Pretreatment and preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6、. . . . . . . 36.2 Austenitizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46.3 Quenching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7、. . . . . . . . . . . . . . . . 66.4 Subzero treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76.5 Tempering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8、. . . . . . . . . . . . . . . . . . . . . . 87 Secondary treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Heat treatment media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9、 . . . . . . . . . . . . . . . . . . . . . . 88.1 Cooling and quenching media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88.2 Subzero treatment media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10、 . . . . . . . . . . . . . . . . . . . 89 Effects of surface hardening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89.1 Effects on case structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11、. . . . . . . . . . . . . . . . . . 89.2 Effects on hardness and effective case depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99.3 Effects on shape and dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12、 . . . . . . 1010 Defects in heat treated products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1011 Designing for heat treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
13、2 Straightening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1313 Testing surface hardened products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Forewor
14、dThis standard has been prepared by Technical Committee Wrmebehandlungstechnik of the Normen-ausschuss Werkstofftechnologie (Materials Technology Standards Committee).1 ScopeThis standard describes the surface hardening of products made of rolled steel, cast iron, or steel powdercompacts.Ref. No. DI
15、N 17022-5 : 2000-03English price group 11 Sales No. 011103.01DEUTSCHE NORM March 200017022-5Continued on pages 2 to 13. No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclu
16、sive right of sale for German Standards (DIN-Normen).Heat treatment of ferrous materialsPart 5: Surface hardeningTranslation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.Page 2DIN 17022-5 : 2000-032 Normative referencesThis standa
17、rd incorporates, by dated or undated reference, provisions from other publications. These normativereferences are cited at the appropriate places in the text, and the titles of the publications are listed below. Fordated references, subsequent amendments to or revisions of any of these publications
18、apply to this standardonly when incorporated in it by amendment or revision. For undated references, the latest edition of thepublication referred to applies.DIN 6773 Heat treatment of ferrous materials Heat treated parts, representation and indications ondrawings *)DIN 17014-3 Heat treatment of fer
19、rous materials Symbols for heat treatment processesDIN 17022-1 Heat treatment of ferrous products Hardening and temperingDIN 17022-2 Heat treatment of ferrous materials Heat treatment methods Hardening and temperingof toolsDIN 17023 Heat treatment of ferrous metals Forms Orders for heat treatment (W
20、BA)DIN 50103-3 Rockwell hardness testing of metallic materials Modified Rockwell scales Bm and Fm(for thin sheet steel)DIN 50190-2 Determination of the effective case depth of heat treated parts after surface hardeningDIN 50192 Determination of depth of decarburization of steelDIN 50601 Metallograph
21、ic examination Determination of the ferritic or austenitic grain size of steeland ferrous materialsDIN EN 571-1 Non-destructive testing Penetrant testing Part 1: General principlesDIN EN 10052 Vocabulary of heat treatment terms for ferrous productsDIN EN 12626 Safety of machinery Laser processing ma
22、chines Safety requirements(ISO 11553 : 1996, modified)DIN EN ISO 6506-1 Metallic materials Brinell hardness test Part 1: Test methodDIN EN ISO 6507-1 Metallic materials Vickers hardness test Part 1: Test method (ISO 6507-1 : 1997)DIN EN ISO 6508-1 Metallic materials Rockwell hardness test (scales A,
23、 B, C, D, E, F, G, H, K, N, T) Part 1:Test method3 ConceptsFor the purposes of this standard, the heat treatment concepts defined in DIN EN 10052 shall apply.4 Principle of methodThe surface layer of a ferrous product is austenitized and then cooled at a suitable rate. Martensite is thus formed,incr
24、easing the hardness of the surface layer and enhancing strength and wear resistance.The area to be hardened is heated to a temperature above Ac3or Acmby means of either flame, induction, laserbeam or electron beam hardening. For each material, the density of the heat flow rate of the heat source and
25、the treatment time produce a specific thermal cycle during which the surface layer is austenitized to a certaindepth at a high heating rate followed by a short soaking time as compared to other heat treatment methods.Because of the transformation behaviour of steel, higher heating rates require high
26、er heating temperatures toobtain a sufficiently austenitic condition. The relationship between the heating rate and temperature can bederived from a time-temperature-transformation (TTT) diagram for continuous heating. Hardening actuallyoccurs during the subsequent quenching of the product. Large ar
27、eas can be hardened either by means of asuitable energy transfer or by moving the product itself.Between the hardened case and the non-hardened core lies a transition zone of several millimetres within whichthe depth of hardness gradually diminishes. The depth of this zone is influenced by the heati
28、ng and quenchingconditions.In many cases, surface hardening is followed by tempering.5 Identification of heat treatment conditionThe heat treatment condition shall be indicated on drawings as specified in DIN 6773.Instructions for performing surface hardening shall be formulated using either the WBA
29、 form specified inDIN 17023 or in a heat treatment plan (WBP). Symbols used to designate the heat treatment method shall beas specified in DIN 17014-3.*) Currently at draft stage.Page 3DIN 17022-5 : 2000-036 Procedure6.1 Pretreatment and preparationProducts shall be pretreated and prepared to ensure
30、 a material condition suitable for surface hardening,particularly in terms of microstructure and residual stresses, and to obtain the required core strength in the finalcondition.Prior to laser hardening, it may be necessary to clean the product surface and pretreat it to improve absorption.Prior to
31、 electron beam hardening, the surface shall be cleaned and, if necessary, demagnetized.6.1.1 Pretreatment6.1.1.1 Stress relievingIf residual stresses (e.g. due to cutting processes) might cause distortion of the product during treatment, it isrecommended that stress relieving be carried out. Any res
32、ulting distortion can then be corrected by subsequentmachining, although there shall be an allowance great enough to eliminate any unwanted changes to the surfacelayer (e.g. decarburization).The stress relief temperature shall be close to, but shall not exceed, the transformation temperature Ac1of t
33、hematerial being treated. In the case of quenched and tempered products, this temperature shall be lower than thetempering temperature in order to maintain strength, and soaking for more than thirty minutes during the heatingphase will not be necessary. Heating and cooling shall be carried out slowl
34、y to prevent new residual stressesfrom building up.Cold-worked products should not be stress relieved, but rather normalized, if there is a risk that recrystallizationwould result in grain coarsening.6.1.1.2 NormalizingResidual stresses in untreated products may also be relieved by normalizing, whic
35、h at the same time alters themicrostructure, thus preventing grain coarsening in critical areas.Normalizing parameters (normalizing temperature and duration, cooling) shall be taken from the steelmanufacturers specifications or other documents.6.1.1.3 Quenching and temperingIt may be necessary to su
36、bject the product to quenching and tempering prior to treatment to obtain the desiredstrength and a homogenous material condition. See DIN 17022-1 and DIN 17022-2 regarding the procedure.To ensure that any changes to the surface layer (e.g. decarburization or oxidation) which occur during quenchinga
37、nd tempering do not adversely affect subsequent treatment, the product surface should be machined beforefurther treatment.6.1.1.4 OxidizingPrior to laser hardening, it may be necessary to oxidize the surface to promote the absorption of the laser beamby the material. Normally, this is done by anneal
38、ing the material in water vapour at a temperature between 450 Cand 550 C.6.1.2 PreparationMachining or cutting residues (e.g. oxide layers, residues of cooling lubricants, cleaning agents or preservatives)can impede the surface hardening process, as can chips, burrs, rust, scale and nonferrous metal
39、s. Theevaporation of residues during electron beam hardening can adversely affect the vacuum, while during laserhardening such residues can affect the transfer of energy to the surface layer.It is therefore necessary to carefully treat and thoroughly clean the products prior to hardening, depending
40、onthe degree of surface impurities and the required quality. The surface can be cleaned by washing, deburring,blasting or pickling.6.1.2.1 WashingNormally, products are washed in hot water with suitable cleaning agents. To ensure that the surface is fullycleaned, it may be necessary to subject the s
41、urface to water-blast cleaning or ultrasound cleaning prior towashing. After washing, the products shall be thoroughly dried.6.1.2.2 DeburringBurrs caused by machining can be removed by blasting, or chemical or thermal deburring. It should be notedthat thermal deburring processes oxidize the product
42、s surface, while in chemical processes the material reactswith the electrolyte, so that in both cases treatment with electron beams or lasers can be impeded.When removing adherent chips, the product should be demagnetized.6.1.2.3 BlastingDry or wet blasting with suitable cleaning agents can be used
43、to remove burrs, scale, rolling, forging or castingskin, colorants or flux residues.Page 4DIN 17022-5 : 2000-036.1.2.4 PicklingPickling is suitable for removing rust, scale, or rolling, forging or casting skin. Care should be taken to fullyremove all pickling residue, since this can begin to rust. F
44、urthermore, too intensive pickling can leave pits in thesurface layer.6.1.2.5 CoatingPrior to laser hardening, it may be necessary to supply the product with a coating that promotes laser beamabsorption (e.g. using graphite powder).6.1.2.6 Edge protectionPrior to flame or induction hardening, it may
45、 be necessary to protect edges in the area to be hardened fromoverheating. This can be done by fitting suitable copper inserts into undercuts, flutes, slots, holes, etc.6.2 AustenitizingSurface hardening involves a localized heating of a products surface layer to austenitizing temperature for acerta
46、in length of time, with the heating process being performed once or several times, using one of several heatsources.The heating rate is determined by the energy supplied by the heat source and the heating time. The resultingtemperature profile for the heated case is a function of the type and densit
47、y of the flow rate of the heat source,the exposure time and the type of material being treated. The objective is to maintain a uniform temperaturedistribution within a localized heated area. Care should be taken to ensure that the maximum temperature withinthe case does not exceed the melting temper
48、atures of the different phases1) in the material.With surface hardening, the austenitizing temperature is reached within a much shorter time than with furnaceheating, due to the relatively high density of heat flow rate (cf. table 1). For sufficient austenitizing, it is thereforenecessary to heat to
49、 temperatures which are 50 C to 100 C higher than furnace temperatures, taking care thatthe temperatures in the external regions of the product are below the melting temperature of the material, to avoidunwanted fusion.Table 1: Density of heat flow rate of various heat sourcesHeat sourceDensity of heat flow rate, Effective case depth,in W/cm2in mmLaser beam 103to 1040,01 to 1Electron beam 103to 1040,01 to 1Induction:MF103to 1042 to 8HF 0,1 to 2HF-impulse 0,05 to 0,5Flame 103to 6 . 1031,5 to 10Plasma beam 104Salt bath (convection) 2
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