ugaarguy
Member
- Joined
- Mar 19, 2006
- Messages
- 13,828
That would depend on the tool steel. CruWear is pretty tough for a tool steel, and even tougher in powder metallurgy form with the smaller, more uniform carbides. Then there's 52100, which is an extremely tough ball bearing steel, that I commonly see it get lumped in with tool steels. Of course there's also Cronidur 30 (AKA LC200N and Z-FiNit), a PESR (pressurized electroslag remelting) modification of 52100, with nitrogen replacing much of the carbon for extremely high corrosion resistance, but retaining most of 52100's toughness. Interestingly, the early jet turbine bearing steels were derived from high speed tool steels, because jet engines obviously get very hot, so their bearings need retained hardness at high temps, like high speed tool steels have. Yet, I don't see these jet engine bearing steels, like 154CM / ATS-34, discussed along with tool steels like I do 52100. Once again, the powder metallurgy versions (RWL34 / CPM-154) achieve even greater toughness.Tool steels are made to be wear resistant (which means good edge retention and high hardness), but usually those properties come at the cost of decreased toughness (increased brittleness, if you will).
Also, wear resistance is largely a function of the type of carbides. For example, AEB-L can be taken past 60 HRC and still be very tough (impact resistant). It doesn't have good wear resistance because it has (relatively) soft chromium carbides since it's composition lacks more exotic elements like niobium, vanadium, and tungsten. All of those elements form very hard carbides that contribute to high levels of wear resistance (edge holding) in steels that have large amounts of them in their compositions. For things like razor blades and kitchen knives that aren't cutting through abrasive materials like paper and carboard, AEB-L is excellent because it's toughness allows it to be ground very thin even when heat treated to high levels of hardness, without worry of excessive edge chipping.