Printed from Kezuriba (kezuriba.net/en/materials/skh51/)
SKH51
ISO P (steel)High-speed tool steels (molybdenum type). Standard: JIS G 4403 (Not confirmed).
🌐International equivalents
“Close” means composition or properties are not exactly the same. Before substituting, check the values in each standard.
| System | Designation | Number | Relation | Confidence |
|---|---|---|---|---|
| JIS | SKH51 | JIS G 4403 | — | |
| AISI | M2 | UNS T11302 | close | Agrees in 2+ sources[1][8][9][10] |
| EN | HS6-5-2C | 1.3343 | close | Agrees in 2+ sources[1][9][3][11] |
| GB | W6Mo5Cr4V2GB/T 9943 high-speed tool steels | close | Agrees in 2+ sources[8][9] |
Differences between the equivalents (from the sources)
- AISI M2: Agrees between Proterial (YXM1: AISI-M2 / JIS-SKH51), Kyocera's comparison table, Baosteel's die steel page and Nachi-Fujikoshi's catalog. UNS T11302 was confirmed only at Carpenter. The AISI column in Proterial's table has C 0.78–0.88, Si 0.20–0.40, Mo 4.50–5.50, W 5.50–6.75 and V 1.60–2.20, so its ranges are wider than JIS
- EN HS6-5-2C: Proterial, Baosteel and Nachi-Fujikoshi list SKH51 and 1.3343 in the same row (Kyocera gives only the designation HS6-5-2). However, in Proterial's table the C of 1.3343 is 0.86–0.94, higher than JIS SKH51 (0.80–0.88). The ranges of the other elements are the same. Dörrenberg and Böhler describe 1.3343 as equivalent to AISI M2
- GB W6Mo5Cr4V2: Agrees between Kyocera's comparison table (SKH51 = W6Mo5Cr4V2 = M2) and Baosteel's die steel page (W6Mo5Cr4V2 = M2 = SKH51 = 1.3343). GB-side composition could not be obtained from primary sources
📄Related specifications (AMS, ASTM etc.)
Specifications called up on purchase orders and drawings. AMS are SAE aerospace material specifications, split by product form (bar, plate, forging), melting practice and heat treatment. Standard texts are paid, so only titles and scopes checked on the publishers’ public pages are shown.
| Spec | Scope | Confidence |
|---|---|---|
| ASTM A600 | Standard Specification for Tool Steel High SpeedTungsten-type and molybdenum-type high-speed tool steels (annealed bars, forgings, plates, etc.). M2 is included in the overview on the ASTM page. The current edition is A600-92a(2024) | Agrees in 2+ sources[12][13] |
All ASTM standards on Kezuriba: ASTM standards quick reference.
⚗Chemical composition (mass %)
As specified in JIS G 4403 (JIS column of the Proterial YXM1 page)
⚖Density
8.07 g/cm³
One source / reference[7]
Value at 20℃ for Böhler S600 (EN 1.3343 HS6-5-2C). The density of SKH51 itself was not found in Japanese manufacturers' materials; it is treated as a reference value for a steel of similar composition
Calculate weight in SKH51 →💪Mechanical properties
“Reference” values are not specified minimums from the standard but figures published by makers and others.
| Condition | Tensile MPa | Yield MPa | Elong. % | Hardness | Type of value |
|---|---|---|---|---|---|
| Annealed (800–880℃, slow cooling) | — | — | — | HBW 255 max | Delivery hardness in the manufacturer's materials (Proterial YXM1). Dörrenberg gives a maximum of 269 HB for EN 1.3343, so the EN steel has a higher upper limit One source / reference[1] |
| Quenched 1220–1240℃ oil cooled (salt bath) + tempered 550–570℃ air cooled | — | — | — | HRC 63 min | Standard heat-treatment hardness in the manufacturer's materials (Proterial YXM1) One source / reference[1] |
| Quenched 1200–1250℃ oil cooled / salt bath + tempered 540–600℃ air cooled ×3 | — | — | — | HRC 55–63 | Value in the manufacturer's materials (Sanyo QH51) One source / reference[2] |
| Recommended hardness by application | — | — | — | For cutting tools HRC 64–66 / for plastic working HRC 58–61 and 61–64 | Reference value (supplied hardness of Nachi-Fujikoshi SKH9 [JIS SKH51]) One source / reference[3] |
1 MPa ≈ 145 psi (0.145 ksi). Hardness conversion · unit converter
🔧Machinability notes (as stated in the sources)
- Sandvik Coromant states that for high-alloy steels, machinability decreases as alloy content and hardness increase, and that for high alloys up to a hardness of 450 HB the cutting edge needs heat resistance. After quenching (over 45 HRC) it is treated as ISO H[4]
📚Sources
Primary sources (public documents from makers, industry associations and standards bodies), numbered where each value is cited. Many are in Japanese.
- proterial.com https://www.proterial.com/e/yss/search/yxm1.html
- sanyo-steel.co.jp https://www.sanyo-steel.co.jp/english/product/special_steel/images/pdf/tool_steel_201712.p…
- nachi-fujikoshi.co.jp https://www.nachi-fujikoshi.co.jp/dcms_media/other/S2001E-6.pdf
- sandvik.coromant.com https://www.sandvik.coromant.com/en-us/knowledge/materials/workpiece-materials
- kyocera.co.jp https://www.kyocera.co.jp/prdct/tool/wp-content/uploads/2014/07/2024-2026_A.pdf
- sumitool.com https://www.sumitool.com/downloads/cutting-tools/general-catalog/assets/pdf/a.pdf
- bohler-edelstahl.com https://www.bohler-edelstahl.com/app/uploads/sites/248/productdb/api/s600_en_gb.pdf
- kyocera.co.jp https://www.kyocera.co.jp/prdct/tool/wp-content/uploads/2016/06/R_2016.pdf
- esales.baosteel.com http://esales.baosteel.com/baosteel_bsi/sso_teg/cp_pages_tggmjg.jsp
- carpentertechnology.com https://www.carpentertechnology.com/alloy-finder/M2
- doerrenberg.de https://doerrenberg.de/fileadmin/special_steel/files/pdf_en_products_neues_Design/1.3343_e…
- astm.org https://www.astm.org/standards/a600
- store.astm.org https://store.astm.org/a0600-92ar16.html
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