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SK-5 is a carbon tool steel you may see in practical fixed blades and cutting tools. It is also listed as SK85 by Kobe Steel. Its appeal depends on the finished knife’s heat treatment and geometry, and it needs the cleaning and drying you would expect from a non-stainless blade.
What Are SK-5 and SK85?
Kobe’s specification explicitly lists SK85 with SK5 in parentheses, so these names belong together in one guide. The selected composition below comes from that producer’s grade table. It is not an analysis of a particular knife, and the small chromium allowance does not make this a stainless steel.
What Matters in a Knife Made from SK-5?
Look at blade thickness, the grind behind the edge and the maker’s heat-treatment information. A stout outdoor blade and a thin slicing blade can behave very differently even with the same steel name. Do not infer a finished knife’s hardness from a producer stock table or assume a maker’s general durability claim predicts your use.
Sharpening and Rust Care
Clean and dry SK-5 after wet use, and apply a suitable protective oil for storage. Use a food-safe product where appropriate. A coating does not protect the exposed cutting edge. When sharpening, match the existing angle for maintenance and use a grit suited to the work; removing damage takes more shaping than a light touch-up.
When Is SK-5 Worth Considering?
Consider the complete knife and how you will care for it. SK-5 can be a practical option when the design suits your cutting and you are comfortable maintaining a non-stainless blade. For prolonged wet exposure, a stainless alternative may be more convenient. Avoid choosing on claims that carbon steel is always tougher or easier to sharpen; treatment and geometry still matter.
Composition
Our composition guide explains what alloy values can and cannot tell you.
SK-5 / SK85: Kobe Steel listing of JIS SK85 (SK5) carbon tool steel; ranges are grade analysis, not a blade assay. Kobe Steel: special steel sheets.
| Element | SK-5 / SK85 |
|---|---|
| Carbon (C) | 0.8–0.9% |
| Chromium (Cr) | ≤0.3% |
Compare Two Knife Steels
Sources and Update Notes
This steel is not included in the numerical ratings used by our comparison tool.
