OHNS (oil hardening, non-shrinking) steel is a general-purpose cold-work tool steel, equivalent to AISI O1. It hardens in oil to about 58–62 HRC with little change in size, so it is widely used for punches, small dies, gauges and cutting tools in Indian tool rooms.
Quick facts
- Type
- Oil-hardening cold-work tool steel
- Main alloys
- Manganese, chromium, tungsten, a little vanadium
- Hardness
- About 58–62 HRC after hardening and tempering
- Hardening
- Oil quench from about 790–820 °C
- Size change
- Small (the 'non-shrinking' in its name)
- As supplied
- Annealed, about 220 HB max, for machining
Equivalent grades
| Standard | Grade |
|---|---|
| AISI | O1 |
| DIN / W.Nr. | 100MnCrW4, 1.2510 |
| JIS | SKS3 |
| India (common name) | OHNS |
Equivalents are close, not identical. Name the grade and standard on the drawing.
Typical chemical composition
| Element | % |
|---|---|
| Carbon (C) | About 0.85–1.00 |
| Manganese (Mn) | About 1.00–1.40 |
| Chromium (Cr) | About 0.40–0.60 |
| Tungsten (W) | About 0.40–0.60 |
| Vanadium (V) | About 0.05–0.15 |
Values are typical. The exact limits depend on the standard and supplier; ask for the mill test certificate when it matters.
Heat treatment
- Harden: heat to about 790–820 °C and quench in oil
- Temper straight away, about 150–250 °C, for 58–62 HRC
- Grind after hardening to final size
- Pre-heat larger tools to reduce cracking risk
Typical uses
- Punches and blanking dies for short and medium runs
- Gauges, templates and measuring tools
- Shear blades and cutting tools for paper, wood and plastics
- Bushes and wear parts in jigs and fixtures
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Questions
- What does OHNS stand for?
- Oil Hardening Non-Shrinking. It hardens in oil with only a small change in size.
- OHNS or D2?
- OHNS is cheaper and easier to machine and harden; D2 has much higher wear resistance and suits long production runs and abrasive materials.
- What hardness can OHNS reach?
- About 58–62 HRC after oil quenching and low-temperature tempering.
The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 9 October 2026.