1、ICS 25.200Wrmebehandlung von Eisenwerkstoffen Verfahren der Wrmebehandlung Teil 4: Nitrieren undNitrocarburierenIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.ContentsPageForew
2、ord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3、 . . . . . . . . . . 22 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4、 . . . . . . . . . . . . . . . 24 Principle of methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.1 Nitriding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5、. . . . . . . . . . . . . . . . . . . . . . . 24.2 Nitrocarburizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Purpose of nitriding and nitrocarburizing . . . . . . . . . . . . . . . . . . . . . . . . . . .
6、 . . . . . . . . . . . . . . . . . . . 26 Identification of heat treatment condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7、. . . . . . . . . . . . . . . . . . 37.1 Pretreatment and preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37.2 Heating to treatment temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8、. . . . . . . . . . . . . 47.3 Nitriding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57.4 Nitrocarburizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9、 . . . . . . . . . . . . . . . . . . . . . . 77.5 Cooling/quenching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77.6 Secondary treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10、 . . . . . . . . . . . . . . . . . . . . . . . . 78 Heat treatment media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78.1 Nitriding media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11、. . . . . . . . . . . . . . . . . . . . . . . . . . . . 78.2 Nitrocarburizing media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88.3 Cooling and quenching media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12、 . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Effects of nitriding and nitrocarburizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89.1 Effects on case structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13、 . . . . . . . . . . . . . . . . . . . . . 89.2 Effects on hardness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109.3 Effects on shape and dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14、. . . . . . . . . . . . . . . . . . 1110 Heat treatment equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1110.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15、 . . . . . . . . . . . . . . . . . . . 1110.2 Equipment for nitriding and nitrocarburizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1110.3 Equipment for cooling and quenching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16、. . . . . . 1211 Testing nitrided and nitrocarburized products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1212 Straightening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
17、13 Designing for heat treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1214 Defects in heat treated products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Bibliography . .
18、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Ref. No. DIN 17022-4 : 1998-01English price group 11 Sales No. 011103.01DEUTSCHE NORM January 199817022-4Continued on pages 2 to 16. No part of this tr
19、anslation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).Heat treatment of ferrous materialsPart 4: Nitriding and nitrocarburizingTranslation
20、by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.Page 2DIN 17022-4 : 1998-01ForewordThis standard has been prepared by Technical Committee Wrmebehandlungstechnik of the NormenausschussWerkstofftechnologie (Materials Technology Standar
21、ds Committee).1 ScopeThis standard describes the heat treatment methods nitriding and nitrocarburizing, especially of productsmade of rolled steel, cast steel, or cast iron, or steel powder compacts.2 Normative referencesThis standard incorporates, by dated or undated reference, provisions from othe
22、r 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 apply to this standardonly when incorporated in it by amendment or r
23、evision. For undated references, the latest edition of thepublication referred to applies.DIN 6773 Heat treatment of ferrous materials Heat treated parts, representation and indicationson drawings*)DIN 17014-3 Heat treatment of ferrous materials Symbols for heat treatment processesDIN 17022-1 Heat t
24、reatment of ferrous products Hardening and temperingDIN 17022-2 Heat treatment of ferrous materials Heat treatment methods Hardening andtempering of toolsDIN 17023 Heat treatment of ferrous metals Forms Orders for heat treatment (WBA)DIN 17052 Heat treatment furnaces Requirements relating to uniform
25、ity of temperatureDIN 17211 Nitriding steels Technical delivery specificationsDIN 50133 Vickers hardness testing of metallic materials HV 0,2 to HV 100DIN 50190-3 Determination of the effective case depth of heat treated parts after nitridingDIN EN 10052 Vocabulary of heat treatment terms for ferrou
26、s productsISO 4516 : 1980 Metallic and related coatings Vickers and Knoop microhardness testsISO/DIS 4516 : 1999 Metallic and related coatings Vickers and Knoop microhardness tests*)3 ConceptsFor the purposes of this standard, the heat treatment terminology given in DIN EN 10052 shall apply.4 Princi
27、ple of methods4.1 NitridingNitrogen is introduced into the surface layer of a ferrous product, the nitrogen source usually being ammoniaunder normal atmospheric pressure, although in the case of plasma nitriding the source is nitrogen. Thetreatment is carried out at a temperature below the eutectoid
28、 temperature of the iron-nitrogen system, preferablyat a temperature between 480 C and 550 C, and lasts for several hours to several days. Upon completion ofthe treatment, the product is usually cooled in a gaseous medium to room temperature.If the nitriding medium contains oxygen, the process is ca
29、lled oxynitriding, while if sulfur is present, it may bereferred to as sulfonitriding.Nitriding is primarily used to treat alloyed ferrous products.4.2 NitrocarburizingHere both nitrogen and carbon are introduced into the surface layer of a ferrous product. The treatment mediumis either a salt bath,
30、 gas or powder, although plasma can also be used. The treatment is carried out preferablyat a temperature between 570 C and 580 C, and lasts for a few minutes to several hours.Upon completion of the treatment, the product is either cooled in a gaseous medium or quenched in a liquid;this may be follo
31、wed by ageing.If the nitrocarburizing medium contains oxygen, the process is called oxynitrocarburizing, while if sulfur ispresent, it is called sulfidizing.Nitrocarburizing is used to treat both alloyed and unalloyed ferrous products.5 Purpose of nitriding and nitrocarburizingNitriding and nitrocar
32、burizing are used to enhance the fatigue strength and corrosion resistance of ferrousproducts.*)*) Currently at draft stage.*) Translators note. In English, both nitriding and nitrocarburizing are considered case hardening processes.Page 3DIN 17022-4 : 1998-01Nitriding is primarily used on alloyed s
33、teel in particular the so-called nitriding steel specified in DIN 17211 to create a hard case which will enhance the fatigue strength of the product, as well as its resistance to weardue to adhesion, abrasion and rolling strain.With nitrocarburizing, a compound layer rich in both nitrogen and carbon
34、 is produced to lower the coefficientof friction, wear and corrosion resistance.6 Identification of heat treatment conditionThe heat treatment condition shall be indicated on drawings as specified in DIN 6773.Instructions for performing nitriding or nitrocarburizing shall be formulated using either
35、the WBA form specifiedin DIN 17023 or in a heat treatment plan (WBP). Symbols used to designate the heat treatment method shallbe as specified in DIN 17014-3.7 Procedure7.1 Pretreatment and preparationProducts shall be pretreated and prepared to ensure a suitable surface condition, to ensure that re
36、sidual stressesdo not interfere with the heat treatment process, and to localize the effects of the treatment, if so desired.7.1.1 Pretreatment7.1.1.1 Stress relievingIf residual stresses (e.g. resulting from machining) might cause distortion of the product during treatment, it isrecommended that st
37、ress relieving be carried out at a temperature that is 30 C above treatment temperature.Any resulting distortion can then be corrected by subsequent machining, although there shall be an allowancegreat enough to allow full removal of any unwanted changes to the surface layer (e.g. decarburization).T
38、he stress relief temperature shall be close to, but shall not exceed, the transformation temperature Ac1of thematerial 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
39、thirty minutes during the heatingphase will not be necessary. Heating and cooling shall be carried out slowly 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 coa
40、rsening.7.1.1.2 NormalizingResidual stresses in untreated products may be relieved by normalizing, which at the same time alters themicrostructure, thus preventing grain coarsening in critical areas.Normalizing parameters (temperature and duration, cooling) shall be taken from the steel manufacturer
41、sspecifications or other documents.7.1.1.3 Quenching and temperingIt may be necessary to subject the product to quenching and tempering prior to nitriding or nitrocarburizing toobtain the desired strength. See DIN 17022-1 and DIN 17022-2 regarding the procedure.The tempering temperature should be ab
42、out 30 C above the nitriding/nitrocarburizing temperature. Note thatthe tempering temperature and time have an influence on the hardness profile.To ensure that any changes to the surface layer (e.g. decarburization or oxidation) which occur during quenchingand tempering do not adversely affect subse
43、quent treatment, the product surface should be machined beforefurther treatment.It can be expected that nitriding or nitrocarburizing over several hours will result in reduced hardness andstrength in the products core, depending on the tempering resistance of the material.7.1.2 PreparationMachining
44、or cutting residues (e.g. oxide layers, residues of cooling lubricants, cleaning agents or preservatives)can greatly impede nitrogen absorption, especially in the case of gas nitriding or nitrocarburizing. Furthermore,chips, burrs, rust, scale and nonferrous metals can alter the chemical composition
45、 of salt baths and thus inhibittheir effect. It is therefore necessary to thoroughly clean or otherwise treat the products prior to nitriding/nitrocarburizing, depending on the degree of surface impurity and the required quality. The products and theirholders are to be dried after cleaning.Bolts or
46、screws used to plug bores or threaded holes shall be removed before cleaning. For safety reasons, partswith sealed hollow spaces are not to be nitrided or nitrocarburized.7.1.2.1 CleaningProducts shall be cleaned to remove any surface residues (e.g. cooling lubricants, preservatives, scale, rust,col
47、oring or fluxing agents), as well as adherent chips, rolling or forging skin. Cleaning methods include washing,deburring, blasting, pickling and oxidizing.7.1.2.1.1 WashingNormally, products are washed in hot water with suitable cleaning agents. To ensure that the surface is fullycleaned, it may be
48、necessary to subject the surface to water-blast cleaning or ultrasound cleaning prior towashing.After washing, the products shall be thoroughly dried, for when they are placed in the furnace, any moisture onthem can lead to a rise in pressure during the heating phase. In addition, insufficiently dri
49、ed products can causedangerous eruptions in the salt baths when nitrocarburizing.7.1.2.1.2 DeburringBurrs caused by machining can be removed by blasting, or chemical or thermal deburring. It should be notedthat thermal deburring processes oxidize the products surface, while in chemical processes the material reactswith the electrolyte, so that in both cases the absorption of nitrogen can be impaired.When removing adherent chips, the product should be demagnetized.7.1.2.1.3 BlastingDry or wet blasting with suitable cleaning agents
