questions about M-2 steel

fast14riot

fast14riot

Joined
Oct 27, 2010
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I have recently found some M-2 steel locally and know it can make decent blade steel, but after doing my required searching for info, I have come up almost empty handed. I am looking for info on annealing since it is hardened when I get it. Also any tips working with it would be great. Anyone here ever work with it?


-Xander
 
I haven't worked with it (actually, I've worked with it a lot, just never heat treated it), and the reason is the complexity of the HT.

The anneal is something like soak at 1600 then cool at a rate no faster than 30 de per hour until under 1000 (my texts disagree on the rate of cooling). To harden you heat in the range of 2,100 and quench in molten salt or interrupted oil quench to under 1000F, then air cool.

And now you see why I leave that one alone...
 
This came from asm heat treater's guide. It is a long process. Cooling from 1600F to
1200F at 10F/h will take 40 hours!

Annealing. Heat to 870 to 900 C ( 1600 to 1650 F). Use lower limit for
small sections and upper limit for large sections. Pack annealing in tightly
closed containers or using a controlled atmosphere or vacuum is required
to minimize decarburization. The packing material can be dry sand or lime
to to which a small amount of charcoal has been added. Burned cast iron chips
are also satisfactory. Use a container that is only slightly larger than the load
to minimize the amount of packing material required. This allows the pack
to heat rapidly. After the steel has reached the annealing temperature. it
should be held at temperature for 1h per inch of thickness of the container.
Cool slowly in furnace to 650 C ( 1200F) at a rate not to exceed 22 C
(10 F) per h. after which a faster cooling rate will not affect final hardness.
 
Hmmm.... well maybe that's why I should just stick to 10xx steel. Looking at the amount of Cr and W I don't think it will be easy to work hardened even at only ~.070" thick. Only reason I was thinking about getting it is for some old slip joints I have with broken blades. I think I'll pass on it.

Thanx guys!

-Xander
 
Thermal Treatments

Critical Temperature: 1530F(830C).

Forging: 2075F(1135C) Do not forge below 1700F(925C). Slow cool after forging.

Annealing: 1600F(870C), hold 2 hours, slow cool 25F(15C)/ hr max. to 1000F(535C), then air or furnace cool. Hardness BHN 217/255. Stress Relieving: 1100-1300F(595-740C), hold 2 hrs. and air or furnace cool.

Straightening: Best done warm 400-800F(205-425C.)

Hardening: (Salt Baths or Vacuum Furnace preferred.)

Preheat: 1500-1550F(815-845C), equalize.

High Heat: 2100-2225F(1150-1220C), soak 2 to 5 minutes. For vacuum hardening, use the high side of the high heat range and soak times.

Quench: Salt or oil to 1000-1100F(540-595C), equalize, then air cool to hand warm, 150F(65C). Temper immediately. The vacuum quench rate to below 1000F(540C) is critical to achieve comparable results.

Temper: Tempering at 1000F(540C) or higher 2 times for at least 2 hours at temperature is recommended. Air cool to room temperature between tempers.

Hardening Data
Oil quenched.

--------------------------------------------------------------------------------

Tempering
Hardness HRC
Temperature
2100F
(1150C)
2150F
(1175C)
2250F
(1230C)

°F
°C


--------------------------------------------------------------------------------

975 524 64 65 66
1000 540 64 65.2 66.8
OPTIMUM FOR MAXIMUM TOUGHNESS AND EFFECTIVE STRESS-RELIEVING.
1025 550 63.5 65.1 66.8
1050 565 62.6 64.8 66
1075 580 61.3 64 65
1100 595 60 62.5 64
1125 605 58.4 60.5 62.4
1150 620 57 58 60.9
1175 635 – – 59
1200 650 – – 57

This is from Crucible. BTW Crucible's CPM M4 makes a better blade.
 
Grind it hard. It can be done, but you dont have to worry about heat treating it, so you can go straight from grinding to done.
 
Mete - thanx for the chart. Looks like high heat resistance before ruining temper so grinding fully hard may be possible.

Neb - I may try profiling on a bench grinder with old stones, only thing is I don't know the exact hardness of the steel available to me, so hopefully it isn't too brittle. I don't think hand rubbed satin finish will be easy. Also drilling is going to take some serious effort and a large stack of bits!



-Xander
 
I've made a couple dozen blades from pre-hardened M-2, I love it, it's not as bad as hardened D-2, but like the above posters say it looks like a PITA to HT
 
Unless my head math is off, 22C per hour is not 10F per hour. It should be about 40F per hour.
 
How much of it is available? I am near you, and if you cannot use it I can. I have EDM capabilities, and my be interested. PM me, I might be able to help with the Pivot holes.
 
bladsmth said:
Unless my head math is off, 22C per hour is not 10F per hour. It should be about 40F per hour.
Click to expand...

Yep bladsmth, you are right again. I copied the data without thinking and a faint '4' looked like a '1'. My bad. Still 10 hours qualifies as a PITA to me :-)
 
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