Tool Steels - Designations and Specifications in Relation to Australian Standards

Australian Standards

Tool steels are covered in Australian Standard AS1239 and with some minor modifications in grouping it is an endorsement of the American AISI tool steel classification.

Similarly British Standard 4659 is an endorsement of the AISI classification.

German Specifications

The DIN system of tool steel classification requires a good knowledge of the German system of numbers, codes and other identifications. The reader is recommended to refer to Stahlschlussel.

The following description of the system is meant for the purpose of elementary familiarisation.

Tool steels are generally regarded as higher alloy steels containing more than five per cent of alloying elements, but this division is not always maintained in practice.

High alloy steels are differentiated from low alloy steels by the symbol X which is always used. Carbon content is obtained by multiplying the mean carbon content by 100. Chemical symbols for the alloying elements are arranged in descending order of content.

Chemical symbols are followed by a series of numbers arranged in the same order and a factor of one is used in determining alloy index numbers for high alloy steels.

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For example: AS 1239 grade H13 hot work tool steel containing 0.35% carbon, 5.0% chromium, 1.5% molybdenum and 1% vanadium would be written as X40CrMoV51.

High speed steels fall into a totally different classification system within the DIN standard. These steels are prefixed by the letter ‘S’ followed by a series of numbers indicating the alloy content. Chemical symbols are not used.

For example: AS 1239 grade M2 Containing 0.85% carbon, 4.0% chromium, 5.0% molybdenum, 6.0% tungsten, 2.0% vanadium would be written as S 6-5-2.

Japanese Specifications

Japanese tool specifications are covered in the Japanese Institute Standard (JIS) Handbook entitled Ferrous Materials and Metallurgy, published by the Japanese Standards Association.

The tool steels are classified into various groups and each group is covered by a separate standard as follows:

JIS standard G4401 carbon tool steels - prefix SK

JIS standard G4403 high speed steels - prefix SKH

JIS standard G4404 alloy tool steels - prefix SKS

JIS standard G4404 high chromium tool steels and hot work - prefix SKD

For example:

High speed steel AS 1239 grade M2 = JIS G4403 grade SKH51

Hot work steel AS 1239 grade H13 = JIS G4404 grade SKD61

 

Source: Abstracted from “IMMA Handbook of Engineering Materials”, 5th Edition.

 

For more information on this source please visit The Institute of Materials Engineering Australasia.

 

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