Are these steels any good for knife blades

[Lowboy]

Grade M42 HSS

C 1.10, Cr 3.8, Mo 9.5, W 1.5, V 1.2, Co 8.0

M42 is a molybdenum series high speed steel alloy with an additional 8% cobalt. It is widely used in metal manufacturing because of its superior red-hardness as compared to more conventional high speed steels, allowing for shorter cycle times in production environments due to higher cutting speeds or from the increase in time between tool changes. M42 is also less prone to chipping when used for interrupted cuts and cost less when compared to the same tool made of carbide. Tools made from cobalt-bearing high speed steels can often be identified by the letters HSS-Co.


This steel is Bandsaw Blade I get from Work, 2" wide x .065 thick



I also have a 650 Brinell material, Armor Plate (mechanical properties are after heat treating)
Chemical Composition (heat analysis - % maximum)

C 0.46, Mn 1.0, P 0.02, S 0.005, Si 1.50 Cr 0.8, Mo 0.5, Al 0.05, B 0.003, CE* 0.82

*CE = C + Mn/6 + (Cr+Mo+V)/5 + (Cu + Ni)/15


Mechanical Properties (typical values)

Hardness Yield* Tensile* Elongation*
BHN Ksi Ksi 2"
600 to 660 230 Ksi 310 Ksi 10% min.

This steel is in 24x24 sheets and 3/16 and 1/4 thick

[Ray Rogers]

Basically, no. The M42 can be used for knives but it is extremely demanding on its heat treatment which means it will require an electric furnace to heat treat successfully. Even if you have a furnace, it will make a good knife but not a great knife. Commonly, M42 is used to make drills.

That other stuff who knows. I'm sure it would make some kind of knife. Bottom line: mystery steel is difficult for the experts to use and almost impossible for the uninitiated to use successfully. We can't tell you how to heat treat it properly. You can simply try it and do the best you can with it and then test the heck out of it and see if you like the result. Or, you could save a lot of time and expense by buying some known blade steel like 1080 so that we can provide accurate information ....

[Doug Lester]

I'm with Ray one this, the M42 would need a soak at high temperature, probably with a pre-soak to get the carbon into solution in the austinite. Both the pre-soak and the soak will need to be at specific temperautres for extended periods of time. Like one half to one hour. It will also be air quenching so there will be no normalization for stress relief and grain control, though some of the alloying elements will retard grain growth. You might also need to do subcrictal heat treatments to decrease carbide size and increase machinability.

For forging it will be very red hard and have a tendency to crumble if not worked within a very narrow range of heats. In short, it would be a nightmare to forge.

The armor plate is not really mystery metal as you know it's composition. Some of what I have to say about it is educated guesswork. I do know that the carbon level is minimal for creating enough martensite by quenching for knife making. It should also form little in the way of carbides for hardness and wear resistance. I would austinize to around 1500-1600 degrees soaking only long enough to make sure it's heated throughout and temper at 350-375 degrees.

The molybdenum, silicon, and chromium levels will cause it to be through hardening in knife dimensions so it's not a steel for hamons or automatic differential hardening as would be expected from many steels with this carbon content. The molybdenum and silicon will increase toughness which usually increases in reverse proportions to hardness and wear resistance. That much molybdenum will also make it slow to move under the hammer if it is use for forging. The aluminum in it is probably just here to deoxidize the steel and will also serve as a drag on grain growth during heat treating, if this steel was ever designed for heat treating.

It looks like this alloy was designed to balance toughness and against strength and hardness and was never intended to be heat treated. You could make a knife from it and it would be usable but not a superior knife. The thicknesses it's available in would make it acceptable for stock removal blades. You could even forge it, especially the 1/4". But, as I said, it would be rather red hard and more difficult to forge than other alloys. You should be able to heat treat it with simpler equipment like a gas forge and a tank of warm oil.

I would recommend more conventional knife steels in both cases, though the armor plate is more workable.

Doug

[Ed Caffrey]

I'm in agreement.....M42 is far too complicated for early knifemaking efforts.....I've been at it a long time, and would not use it.

The armor plate is a flat "No".