Tiêu chuẩn iso 00683 11 2012

© ISO 2012 Heat treatable steels, alloy steels and free cutting steels — Part 11 Case hardening steels Aciers pour traitement thermique, aciers alliés et aciers pour décolletage — Partie 11 Aciers pou[.]

Classification

Steel grades are classified according to ISO 4948-1 and ISO 4948-2 standards Non-alloy special steels include grades such as C10E, C10R, C15E, C15R, C16E, C16R, and 22Mn6 Conversely, all other steel grades covered by ISO 683 are categorized as alloy special steels This classification helps in understanding the composition and appropriate applications of different steel grades.

Designation

For the steel grades covered by this part of ISO 683, the steel names as given in the relevant tables are allocated in accordance with ISO/TS 4949.

5 Information to be supplied by the purchaser

Mandatory Information

When inquiring or placing an order, the purchaser must provide key details including the quantity required, the specific product form (such as slab, bloom, billet, round or square bar, wire rod, sheet, plate, strip, forging, etc.), the appropriate dimensional standard along with dimensions and tolerances or relevant drawings for specialized products like drop forgings, and reference to ISO 683-11 for standard compliance Additionally, the steel type designation must be specified as per Table 3, along with the relevant standard designation for the test report (such as ISO 10474, EN 10204, or JIS G 0415), ensuring clear communication and quality assurance.

Options and/or supplementary or special requirements

This International Standard specifies various options that can be selected by the purchaser, or defaults to basic specifications if none are indicated These options include heat-treatment conditions beyond the untreated state, surface conditions and qualities, restrictions on hardenability scatter bands for alloy steels, supplementary requirements, verification of non-metallic inclusion content, hardenability verification and calculations, suitability for bright drawing, and removal of surface defects If the purchaser does not specify any of these options, products will be supplied in accordance with the default standards outlined in ISO 683.

Copyright International Organization for Standardization

Provided by IHS under license with ISO Licensee=University of Alberta/5966844001, User=sharabiani, shahramfs

This article describes 50 hot-rolled round bars made to ISO 1035-1 standards, featuring a nominal diameter of 40 mm and a length of 8,000 mm The bars comply with diameter tolerances of class S and length tolerances of class L2 per ISO 1035-4, fabricated from steel grade ISO 683-11 20MnCr5 They are supplied in an annealed (+A) heat-treatment condition, with surface blast cleaning (+BC), and include product analysis (Option A.3) An inspection certificate 3.1 according to ISO 10474 accompanies the product, ensuring quality and compliance.

General

The manufacturing process of the steel and of the products is, with the restrictions given by the requirements in 6.2 to 6.4, left to the discretion of the manufacturer.

For minimum reduction ratio or minimum thickness deformation ratio of rolled and forged products, see A.4.

Deoxidation

All steels shall be deoxidized.

Heat-treatment condition and surface condition at delivery

Unless otherwise agreed at the time of enquiry and order, the products shall be delivered in the untreated condition, i.e hot-worked condition.

If so agreed at the time of enquiry and order, the products shall be delivered in one of the heat-treatment conditions given in Table 1, lines 3 to 8.

If so agreed at the time of enquiry and order, the products shall be delivered in one of the particular surface conditions given in Table 2, lines 3 to 6.

Traceability of the cast

The products shall be traceable to the cast, see Clause 10.

Chemical composition, hardness and hardenability

Table 1 gives a survey on combinations of usual heat-treatment conditions at delivery, product forms and requirements as specified in Tables 3 to 7 (chemical composition, hardenability, maximum hardness and hardness range).

Unless otherwise specified, alloy steels must meet the hardenability requirements outlined in Table 5 Upon mutual agreement during inquiry and ordering, steels with restricted hardenability scatter bands, as detailed in Table 6, can be supplied.

The chemical composition determined by cast analysis shall comply with the values in Table 3.

Permissible deviations between the limiting values for cast analysis and the values for product analysis are given in Table 4.

The product analysis shall be carried out when specified, at the time of the enquiry and order (see A.3).

Machinability

All steels are machinable in the conditions “soft-annealed”, “treated to hardness range”, “treated to ferrite/pearlite structure” and “normalized.

Where improved machinability is required, the grades with a specified sulfur range should be ordered and/or with a specific treatment to improve machinability (see also Table 3, footnote c).

Cold shearability

All steels can be cold sheared in the "soft-annealed" condition under proper shearing conditions, such as avoiding local stress peaks, preheating, and using blades with profiles adapted to the product Proper shearing techniques are essential to ensure clean cuts and prevent material deformation Optimizing these parameters enhances the quality and efficiency of the shearing process for various steel types.

Steel grades such as 24CrMo4, 24CrMoS4, 20MnCr5, 20MnCrS5, 15NiCr13, 17NiCrMo6-4, and 18CrNiMo7-6 can be cold shearable under appropriate conditions when delivered in a "treated to improve shearability" state These steels meet specific hardness requirements outlined in Table 7, ensuring optimal performance for cold working processes Proper treatment enhances their shearability, making them suitable for various manufacturing applications requiring precise machining and shaping.

7.3.3 The non-alloy steels and steels 20Cr4, 20CrS4, 16MnCr5, 16MnCrS5, 18CrMo4, 18CrMoS4, 20NiCrMo2-2 and 20NiCrMoS2-2 are, under suitable conditions, cold shearable when delivered in the untreated condition.

Grain size

Unless otherwise specified at the time of enquiry and order, the steel is expected to exhibit a fine grain structure with an austenitic grain size of 5 or finer, as tested according to ISO 643 standards Verification of the grain size can be confirmed by referring to section A.1.

Non-metallic inclusions

Special steels must meet specific cleanliness standards, with non-metallic inclusion content verified through a mutually agreed procedure If an agreement is in place during inquiry and order, microscopic non-metallic inclusion levels should be determined according to ISO 4967 or other standards like EN 10247 or JIS G 0555, ensuring content remains within agreed limits It is important to note that for grades with a specified minimum sulfur content, agreements should exclude sulfide considerations.

This requirement pertains to the verification of macroscopic inclusions in special steels If this verification is required, the method and acceptance limits must be agreed upon during the inquiry and order process to ensure clarity and compliance.

Internal soundness

Surface condition

7.7.1 All products shall have a smooth surface finish appropriate to the manufacturing processes applied.

7.7.2 Minor surface imperfections which may occur under normal manufacturing conditions, such as prints originating from rolled-in scale, are not to be regarded as defects.

Bars and wire rods are supplied with a surface class A in accordance with ISO 9443, ensuring high-quality surface finish Hot-rolled plates and wide flats are delivered with surfaces conforming to ISO 7788, unless specific agreements are made during the inquiry and order process Adhering to these standards guarantees product quality and consistency in surface quality for various applications.

In the absence of an international standard for the surface quality of steel products, detailed specifications related to surface finish should be agreed upon during the inquiry and order process to ensure clarity and meet specific customer requirements.

Detecting and eliminating surface discontinuities is more challenging in coiled products compared to cut lengths This important consideration should be addressed when negotiating surface quality agreements to ensure optimal product standards.

NOTE Bars and wire rod for cold heading and cold extrusion are covered fully by ISO 4954.

7.7.4 If suitability of bars and rod for bright drawing is required, this shall be agreed at the time of enquiry and order.

Removal of surface discontinuities by welding is only permitted with prior approval from the customer or their representative When surface discontinuities are repaired, the method and maximum depth of removal must be agreed upon at the time of inquiry and order, ensuring compliance with quality standards.

Shape, dimensions and tolerances

Nominal dimensions, along with the tolerances for size and shape, should be established during the inquiry and order process, ideally referencing the applicable dimensional standards outlined in Annex C, to ensure clarity and compliance.

Testing procedures and types of documents

Products complying with ISO 683-1.1.1 must be ordered and delivered with inspection documents such as ISO 10474, EN 10204, or JIS G 0415, as agreed upon during the enquiry and order process If no specific document type is specified in the order, a test report will be issued to ensure quality assurance.

If a test report is required as per the initial enquiry and order agreements, it must confirm that the material meets the specified requirements and include the results of the cast analysis for all elements listed in Table 3 for the relevant steel grade.

If the order agreements specify that an inspection certificate 3.1 or 3.2 must be provided, the relevant inspections and tests outlined in section 8.2 must be performed, and the results duly confirmed in the inspection certificate.

The inspection certificate must confirm that the material meets the order requirements, include cast analysis results for all specified elements in Table 3 of the relevant steel grade, and document the outcomes of all inspections and tests mandated by supplementary requirements outlined in Annex A.

`,`,,,,,```,````,`,,`,`````-`-`,,`,,`,`,,` - d) the symbol, letters or numbers relating the test certificates, the test pieces and products to each other.

Frequency of testing

The amount of testing, the sampling conditions and the test methods to be applied for the verification of the requirements shall be in accordance with the of Table 9.

Tests to be carried out for specific inspection

For non-alloy steels and for alloy steels without requirements concerning the verification of hardenability, the hardness requirements according to Table 1, columns 8.2 and 9.2, Table 7 are to be verified.

For alloy steels being ordered with the verification of hardenability, unless otherwise agreed, only the hardenability requirements according to Table 5 and Table 6 are to be verified.

A sufficient number of products shall be inspected to ensure the compliance with the specification.

Chemical analysis

Manufacturers have the discretion to select the most appropriate physical or chemical analytical methods for product analysis In the event of disputes, the analytical method employed must be agreed upon, considering relevant international standards to ensure compliance and accuracy.

NOTE The list of available International Standards on chemical analysis is given in ISO/TR 9769.

Hardness and hardenability tests

Hardness measurements for products in heat-treatment conditions such as +S (treated to improve shearability), +A (soft-annealed), +TH (treated to achieve specific hardness range), +FP (ferritic-pearlitic structure), and +N (normalized) should be conducted following ISO 6506-1 standards, as detailed in Table 7 and Table 9.

Manufacturers of alloy steels can verify hardenability through calculation, with the specific method left to their discretion Upon agreement during the inquiry and order process, they must provide sufficient calculation details to enable customers to confirm the results, ensuring transparency and compliance with technical requirements.

In cases where a calculation formula is unavailable or disputes arise, an end quench hardenability test must be conducted following ISO 642 and Table 9, with the quenching temperature adhering to the specifications in Table 8 Hardness measurements should be performed according to ISO 6508-1, using scale C, to ensure accurate and standardized results.

Retests

Manufacturers must properly mark products, bundles, or boxes to ensure clear identification of the cast, steel type, and origin of the delivery, as outlined in section A.5 Proper marking facilitates traceability and compliance with quality standards.

The table outlines various heat-treatment conditions at delivery, specifying product forms and their requirements as detailed in Tables 3 to 7 It includes combinations applicable to semi-finished products, bars, wire rods, flat products, and hammer and drop forgings, each indicated by specific symbols These classifications help ensure proper application of heat-treatment processes tailored to each product type, adhering to established standards and requirements.

N on -a llo y s te el g ra de s A llo y s te el g ra de s 8 1 8 2 9 1 9 2 9 3 2 U n trea te d N o n e o r + U x x x x x Ch e mi c al c o mp o sit io n ac c o rd in g t o T a ble s 3 an d 4

According to Option 5.2 in Tables 5 or 6, the verification of the hardness ability values is essential Once validated, this includes confirming the hardness verification and, if agreed upon, providing information related to the calculation of the hardness.

3 T re at e d to im p rove shea ra bil ity + S x x - - - B rin el l har d n e s s ac c o rd in g t o T a b le 7

The article discusses the treatment processes involving column treatments, highlighting the application of S4S for thermal annealing to enhance material properties It emphasizes the hardening range achieved through specific treatments and the significance of TH6 in modifying ferrite-pearlite structures for improved durability The section on FP treatment explains its role in normalizing or normalizing forging to refine microstructure, contributing to overall material strength and stability.

Other treatment conditions, such as certain annealing processes to achieve specific structure, can be agreed upon at the time of inquiry and order For example, the condition "annealed to achieve a spheroidization of the carbides (+AC)" required for cold heading and cold extrusion is covered in ISO 4954.

Table 2 — Surface condition at delivery

1 Surface condition at delivery Symbol x indicates in general applicable to

Semi- finished products (as blooms, billets)

Bars Wire rod Flat products

Hammer and drop forgings (see note

Particular conditions supplied by agreement

4 Hot worked and blast cleaned

5 Hot worked and rough machined

The term “hot worked” includes the continuously cast (+CC) condition for semi-finished products, ensuring clarity in manufacturing specifications Definitions such as “rough machined” are based on machining allowances and should be agreed upon during enquiry and order stages to meet project requirements Additionally, surface treatments like oiled, limed, or phosphated finishes can be specified through prior agreement to enhance product performance and surface properties.

Table 3 — Steel grades and chemical composition (applicable to cast analysis) abcd

S Cr Mo Ni Cu max.

15NiCr13 0,12 to 0,18 0,15 to 0,40 0,35 to 0,65 0,025 ≤ 0,035 0,60 to

Elements not listed in this table should not be intentionally added to the steel without the purchaser’s approval, except for finishing the heat, to prevent impairing hardenability and mechanical properties For steels with hardenability requirements, minor deviations from cast analysis limits are acceptable, provided they do not exceed ±0.01% for carbon and conform to Table 4 for other elements Steels with enhanced machinability, achieved through higher sulfur levels or lead additions, can be supplied upon request, with possible adjustments such as increasing manganese content by 0.15% Additional case-hardening steels for bearings are covered by ISO 683-17, and lower silicon content may be agreed upon at the order stage, considering its effect on mechanical properties.

Table 4 — Permissible deviations between the product analysis and the limiting values given in Table 3 for the cast analysis

Permissible maximum content according to cast analysis mass fraction

The nickel (Ni) content in the material ranges from 2.00 to 3.50 with a tolerance of ±0.07 This means that in a single cast, the nickel percentage may slightly exceed the upper limit or fall below the lower limit of the specified range, but not both simultaneously.

Table 5 — Hardness limits for steel grades with specified (normal) hardenability (+H-grades; see 7.1.1)

Hardness HRC at a distance, in millimetres, from quenched end of test piece of

Table 6 — Hardness limits for steels with narrowed hardenability scatterbands (+HH- and +HL-grades)

Hardness HRC at a distance, in millimetres, from quenched end of test piece (in millimetres) of

Table 7 — Hardness requirements for products delivered in the conditions “treated to improve shearability” (+S), “soft-annealed” (+A), “treated to hardness range” (+TH), “treated to ferrite-pearlite structure” (+FP) or “normalized” (+N)

+S +A + TH +FP +N max max min max min max min max.

Table 8 — Conditions for heat treating test bars and treatment of the steels

End quench test austenitizing temperature a

Direct and simple hardening temperature cd

C10R - 880 to 980 830 to 870 880 to 920 780 to 820 150 to 200

C15R - 880 to 980 830 to 870 880 to 920 780 to 820 150 to 200

C16R - 880 to 980 830 to 870 880 to 920 780 to 820 150 to 200

22Mn6 - 880 to 980 830 to 870 880 to 920 780 to 820 150 to 200

20CrS4 900 ± 5 880 to 980 820 to 860 860 to 900 780 to 820 150 to 200

16MnCrS5 900 ± 5 880 to 980 820 to 860 860 to 900 780 to 820 150 to 200

18CrMoS4 900 ± 5 880 to 980 820 to 860 860 to 900 780 to 820 150 to 200

24CrMoS4 900 ± 5 880 to 980 820 to 860 860 to 900 780 to 820 150 to 200

20NiCrMoS2-2 900 ± 5 880 to 980 820 to 860 860 to 900 780 to 820 150 to 200 20MnCr5

20MnCrS5 900 ± 5 880 to 980 820 to 860 860 to 900 780 to 820 150 to 200

17NiCrMo6-4 900 ± 5 880 to 980 810 to 850 830 to 870 780 to 820 150 to 200

15NiCr13 850 ± 5 880 to 980 810 to 850 840 to 880 780 to 820 150 to 200

18CrNiMo7-6 860 ± 5 880 to 980 810 to 850 830 to 870 780 to 820 150 to 200

When carburizing, direct hardening, or tempering, the given temperatures serve as general guidelines; the actual temperature should be selected based on desired properties A minimum austenitizing time is typically 30 minutes Carburizing temperature varies with steel composition, product size, and carburizing medium, generally not exceeding 950 °C for direct hardened steels, though higher temperatures (1020–1050 °C) may be used under special conditions like vacuum carburizing The choice of quenching agent depends on factors such as the shape of the parts, cooling conditions, and furnace load To prevent distortion in direct hardened steels, quenching from a temperature between core-hardening and case-hardening temperatures is recommended Lastly, a minimum tempering duration is around 1 hour to ensure proper tempering effects.

Table 9 — Test conditions for the verification of the requirements given in column 1

Requirements Amount of testing Sampling b Test method

Test unit a sample products per test unit tests per sample product

3 and 4 C (The cast analysis is given by the manufacturer; for product analysis, see A.3)

In cases of dispute, the sampling method should ideally follow ISO 642:1999, 5.1, a) or b) 1) If these standards are not applicable, the sampling method—whether starting from separately cast and hot-worked ingots or cast and not hot-worked samples—is generally left to the manufacturer's discretion unless otherwise specified during the enquiry and order process.

The test shall be conducted in accordance with ISO 642 standards, ensuring standardized procedures The quenching temperature must be set according to the specifications provided in Table 8 to achieve accurate results Hardness measurements are to be determined following Method C of ISO 6508-1, ensuring consistency and reliability in hardness testing.

3 Hardness in the condition +S or +A, +TH or FP

1 1 In cases of dispute, the hardness shall be measured, if possible, at the following point of the surface:

— in the case of round bars, at a distance equal to the diameter from one end of the bar,

For bars with a square or rectangular cross-section and flat products, the specified distance is equal to the material's thickness from the end Additionally, it is placed at 0.25 times the thickness from one longitudinal edge on the transverse side of the product These measurements ensure proper positioning and structural integrity according to manufacturing standards.

For hammer and drop forgings, if the standard requirements are impractical, it is essential to agree on a suitable position for the hardness indentations during the enquiry and order process This ensures clear communication and meets specific manufacturing needs Customizing hardness testing locations helps achieve accurate results and maintain forging quality Early agreement on indentation placement optimizes quality control and aligns expectations between manufacturer and client.

For sample preparation, see ISO 6506-1.

7 C 1 1 The test shall be performed near the surface In accordance with

Verification of requirements is only necessary when an inspection certificate or report is requested, specifically for criteria listed in Table 1, columns 8 or 9 Testing must be conducted separately for each cast ("C"), each dimension ("D"), and each heat-treatment batch ("T") to ensure compliance.

Products with varying thicknesses can be grouped if their thicknesses fall within the same dimensional range for mechanical properties and if differences in thickness do not impact these properties In uncertain cases, both the thinnest and thickest products should undergo testing The selection and preparation of samples and test pieces must comply with the standards outlined in ISO 377 and ISO 14284 to ensure consistent and reliable results.

X distance from quenched end of test piece, mm

Figure 1 — Scatter bands for the Rockwell C hardness in the end quench hardenability test (continued)

Figure 1 — Scatter bands for the Rockwell C hardness in the end quench hardenability test

Tiêu đề	Case-hardening steels
Trường học	International Organization for Standardization
Chuyên ngành	Heat-treatable steels, alloy steels and free-cutting steels
Thể loại	Tiêu chuẩn
Năm xuất bản	2012
Thành phố	Geneva

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