How To Verify Skh51 Reaches Hrc62 65 Hardness Testing Guide For Buyers - China

SKH51 HRC62-65 – The Hardness Window That Defines Tool Performance, And How To Verify It When a purchase order says "hardness HRC 62–65 after heat treatment", both sides need to know exactly how that number will be measured and proven.

SKH51 (JIS standard, equal to AISI M2, DIN 1.3343 and GB W6Mo5Cr4V2) reaches HRC62-65 reliably when chemistry and process are right — this guide explains what influences the final value and how buyers can verify it before payment.

What determines whether SKH51 hits HRC62-65:

1 - Chemistry within window: C 0.80–0.90% provides the carbon for martensite; V 1.75–2.20% and W+Mo carbides sustain hardness at temperature.

A heat at the low end of carbon may land at HRC 62 — acceptable, but know it in advance.

2 - Austenitizing temperature: 1200–1240°C.

Below 1200°C the matrix under-hardens; above 1240°C grains coarsen and brittleness rises.

3 - Triple tempering at 550–580°C: secondary hardening peaks here.

A single temper can leave the tool 1–2 HRC below target with unstable retained austenite.

4 - Section size and quench media: large rounds need gas pressure or salt quench to hit the same hardness as small bars in oil.

How we verify hardness on your behalf:

- Rockwell C testing per ASTM E18 on every heat-treated sample coupon

- Hardness mapping across the bar cross section (surface vs core values reported)

- Mill certificate + heat number on every shipment; third-party inspection (SGS/BV) arranged on request before loading How you can verify at receiving:

1 - Check the mill certificate chemistry matches the stated heat number.

2 - Spot-test hardness on a sample coupon if you have in-house Rockwell equipment — properly annealed stock reads HB 255 max before your treatment.

3 - After your first hardening run, compare achieved HRC against our certificate data; consistent agreement confirms your recipe and our steel are aligned.

Buyer tip: if a supplier quotes SKH51 with hardness "guaranteed HRC 65 minimum" but no chemistry certificate, be cautious — genuine material falls in the 62–65 window depending on section size and exact process, and honest suppliers document both.

Songshun supplies SKH51 in round bar dia 3–300mm, flat bar, plate and cut blocks — all forged on a 7000-ton press, annealed in-house, UT tested on large sections, and shipped with complete documentation.

Stock sizes dispatch within 48 hours.

Send us your hardness specification and application — our engineers confirm achievable values for your section sizes and quote within 12 hours.

Songshun Company Website: https: //songshunsteel.

com/

Company Contact:

• Posted By: Dongguan Songshun Mould Steel Co., Ltd.

• Phone: 0086 0769 85475596

• Address: 1st Floor, No. 1, Dongda Fourth Street, Shatou Community, Chang'an Town, Dongguan , GuangDong , China

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• Website: https://songshunsteel.com/

• Business Description: Established in 2009,Songshun Steel supplies a wide range of carbon, alloy and tool steel products, including high speed tool steel, cold work tool steel, hot work tool steel, plastic mould steel, engineering steel and machine structural steel etc.
  
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