Question about 154 CM

R

RedCrow

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Dec 24, 2018
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I don't make a ton of knives with stainless, but when I do it is always aeb-l or NitroV. The warping we get on those, especially in thinner steels is insane. If I switch to 154-CM, is cryo completely necessary? If I were to skip the cryo, would i just be giving up 1-2 points of hardness, or is there some other drawback to not doing a full cryo? I dont mind giving up just a bit of hardness, if 61 or so is still possible.
 
154Cm yes,,,,minimum dry ice and alcohol. CPM 154 does ok with out cryo but leaving some performance on the table.
 
I am pretty sure that the dry ice/alcohol slurry will take care of most all of the retained austenite in CPM154CM or it's ingot version, 154CM. According to the Crucible data sheet for this steel, "To completely transform any retained austenite, a freezing treatment with dry ice at -100°F (-74°C) is recommended either after the quench or in between the two tempers. The freezing treatment is most effective right out of the quench, however complex parts with sharp corners are more safely frozen between the two tempers. Thin sections can be successfully quenched in forced air and will obtain results to those in the table above."

LN2 would be overkill, as according to Crucible, -100°F "completely transforms any RA".

It is a pretty simple SS, with just 1.05% carbon.
 
How long has cryo been "common practice" with the stainless and high alloy steels?

Like, was Loveless going there,back in the day?

Thanks.
 
Stuart Davenport Knives said:
I am pretty sure that the dry ice/alcohol slurry will take care of most all of the retained austenite in CPM154CM or it's ingot version, 154CM. According to the Crucible data sheet for this steel, "To completely transform any retained austenite, a freezing treatment with dry ice at -100°F (-74°C) is recommended either after the quench or in between the two tempers. The freezing treatment is most effective right out of the quench, however complex parts with sharp corners are more safely frozen between the two tempers. Thin sections can be successfully quenched in forced air and will obtain results to those in the table above."

LN2 would be overkill, as according to Crucible, -100°F "completely transforms any RA".

It is a pretty simple SS, with just 1.05% carbon.
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Those types of comments in datasheets are completely useless. The martensite finish temperature is controlled by the initial austenitization, and even using liquid nitrogen the hardness drops above around 2000-2050F with 154CM, meaning the cold treatment is certainly not completely transforming retained austenite. Knife steels are high carbon steels, carbon is the best element for stabilizing RA, you can have problems with RA with virtually all of them. Even within recommended austenitizing ranges.
 
My answer to folks who don't have cryo is to use the lower austenitization point. If the range is 1900°F to 2000°F, then use 1900° to 1950° and dry ice. You will get good results. Final hardness can be adjusted with a slightly lower temper point. Yes, you may lose a point of final hardness, but the blade will be of good structure, which is more important.
 
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