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How to heat treat Sandvik 14C28N knife steel
Sandvik 14C28N is the latest development in Sandvik’s (Swedish) range of knife steels. The optimized chemistry provides a top grade knife steel with a unique combination of excellent edge performance, high hardness and good corrosion resistance.
Sandvik 14C28N® is an upgrade of 12C27, is recommended for pocket knives, chefs knives, hunting knives and fishing knives.
Sandvik 14C28N® is martensitic stainless chromium steel with a unique combination of properties:
- Excellent edge performance
- Polishes well (Mirror polish)
- Good hardness (62HRC max)
- Good corrosion resistance
M390 Chemical composition (average %)
C: 0.62, Mn: 0.60, Si: 0.2, Cr: 14.0, N: 0.11, P: 0.025 and S: 0.010.
Sandvik 14C28N® which is an upgrade of Sandvick’s own 12C27 and is readily comparable to AEB-L/13C26 and Nitro-V
Here is a composition comparison graph of the steel (visit zKnives.com).
In most steels, carbon is used to increase hardness but 14C28N uses nitrogen . This allows for higher hardness without compromising corrosion resistance.
Sandvik 14C28N heat treatment process:
Austinizing / Hardening
When the blade has been soaked in the furnace for the time specified above, it is removed and immediately quenched, preferably in oil intended for quenching (Genheat 22, etc) not canola nor used motor oil.
- Austenitizing Temperature: 1050°C – 1080°C (1922°F – 1975°F) see summary table below for aditional options
- Soaking Time/s:
- 2.5mm – 5 minutes
- 3.75mm – 10 minutes
- 4mm – 12 minutes
- 5mm – 25 minutes
Recommendation: For most home heat treating, 1060°C (1940°F) is recommended as no extra equipment is needed and high hardness is achieved.
Please note that Sandvik steels are shipped in large strip coils and thus retain a certain amount of that “memory” when heat treated resulting in warping issues. Therefore plates are recommended to alleviate that issue.
- Quenching in oil: quench until black, and then cool in still air to 20°C (70°F) within 30 minutes or less.
- If using Quench plates or compressed air, 600°C (1112°F) should be reached within 1–2 minutes and room temperature 20°C (70°F) within 30 minutes or less.
Sub-zero / Cryogenic Treatment
- Quench, cool and then freeze immediately after hardening and before tempering.
- Remove from cryo and allow blade to warm to room temperature in ambient air.
The maximum hardness of 14C28N is obtained at a retained austenite content of 15%, therefore deep freezing is recommended in order to reach the higher hardness range as well as high corrosion and wear resistance (in combination with higher austenisiting temperatures 1060°C -1080°C).
- The cryogenic treatment with liquid notrogen leads to increased hardness values (62HRC) at austenitising tempersatures >= 1080°C (1975°F)
- Cold treamt with a house hold freezer capable of reaching -20°C (-5°F) can be used with austenitising tempersatures >= 1060°C (1940°F)
Slow heating to tempering temperature.
- Times: 1 Times
- Duration: 2 hours (120 minutes).
Unlike other steels, secondary hardening should be avoided as brittleness and loss of corrosion resistance occur with tempering above 450°C (840°F).
Summary / Results
- 62HRC: 1080°C (1975°F), Deep Freeze to -70°C/-95°F, Tempering at 175°C (345°F)
- 60HRC: 1060°C (1940°F), Deep Freeze to -20°C/-5°F, Tempering at 175°C (345°F)
- 59HRC: 1050°C (1920°F) @175°C (345°F)
- 57 HRC: 1050°C (1920°F) @ 225°C (435°F)
- 59HRC: 1050°C (1920°F) @ 350°C (660°F)
All info above is from my readings of research papers, forum posts, and discussions with people. I am not a metallurgist and the above is presented here for the benefit of all knifemakers. You do not have to follow them and I’ll not be held responsible for any loss or damage you may experience.
Please comment below if you have to add anything to the above.