Thread: General rule for hardness?

All steel alloys are a trade-off between hardness v. toughness. A SR actually needs both characteristics, which dictates a high carbon steel that is properly tempered for this application.

Hardness has limitations; too much and it becomes brittle; too little and it cannot take an edge. Glass is harder than any tempered steel; yet, no engineer would use glass leaf-springs for a car's suspension. This application requires toughness - the ability to recover from torque or bending action. A SR needs hardness to achieve and maintain sharpness. A SR requires toughness to allow the thin edge to bend without breaking when slicing through our tough, copper-like whiskers.

Modern steel alloys are superior to any manufactured prior to WWII, even though I am very nostalgic and mystical about old razors. Stainless steel alloys are much tougher today than even 30 years ago.

BOTTOMLINE: The best SR alloy is a balance of hardness (~58-62 Rockwell) and toughness. Most of the leading manufacturers achieve this objective with modern steel alloys and proven tempering methods.