Thread: Ice Tempered Frozen Steel?

Cryo treatment of steel. It has taken on almost religious qualities and has it's own share of false prophets. I keep trying to come up with an explanation that is short and sweet but that is not easy. But I'll try again.

The reason is to convert retained austenite to martensite. Martensite is the hard form of steel that makes it the good stuff we all want. This crystal is more abrasion resistant, it's harder and tougher and holds the edge longer making that the desirable form of steel for razor edges. Austenite is harder than soft steel but much more brittle and weaker.

Strong carbide formers like chromium, the most common, or other alloying materials influences how much of the carbon can be converted into solution and form austenite when above the critical temperature of the steel and then convert to martensite in the quench.

A steel that has carbon levels below the eutectic point will likely dissolve all the carbon into solution and has little or no retained austenite IF it is heat treated correctly. Hypereutectoid steels will have an excess of carbon available and the likelihood of retained austenite increases because when the martensite forms there is only so much room in the crystalline lattice interstices for the carbon molecule and the excess stuff is trapped as austenite. Alloying elements influence this which is why the steels that gain the most benefit from low temperature quenching are high alloy steels, aka stainless types.

For most carbon steels, correctly heat treated, retained austenite even in say a carbon steel of 0.95% (1095) is inconsequential. There is a risk that any carbon steel that is claimed to improve with cryo treatment has not been heat treated correctly in the first place.

For the record, I'm not for or agin it. I don't do it on my blades. I have argued that the cost does not outweigh any claimed benefit if the basic processes are done right. It does have it's place with the right materials, or because the maker simply has to do it to feel good about themselves or their steel, or as we are all aware of in razors, marketing claims that help make sales. I have more academic criticisms but that makes for a very long answer.

Frankly, as TBS has already intimated, that anyone honing by hand, shaving by hand would have the ability to tell the difference scientifically/objectively. Hmm, now a CATRAL machine setup correctly, maybe, but that's not whiskers. So it would be apples and oranges anyway and we still couldn't be absolutely certain.

Well done Mike!!