M2 vs. M4 steel: advantages? Question for Darrel

Kevin Wilkins

Kevin Wilkins

Joined
Oct 7, 1998
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1,459
Hello Darrel,

was wondering if you've used M4 steel and what you think of it? Does it have real advantages over M2? Will it take RC 62 for short fixed blades?

I can't decide what kind of steel I should use for my next run of knives.
 
I have used many types of steel for other purposes besides knives. The M series is just not a fav of mine for knife blades. I dont see the advantage to this series of steel in blades.. In the applications I have use these materials they were used for hi shock NEGATIVE, NETURAL,SLIGHT POSITIVE rake cutting with backing..
Drills, Gear Hobs ect. IF your thinking your going to get increased life on the edge there are better choices IMHO.. Cpm420v,v10, v15,440v, 52100, ect.. The problem I see is that the m series was designed to have backing or a lot of material behind it for shock.. Knife edges are not backed well . They are thin. I would look for a material that will take the shock of bending and not chip out. If you take m2 or 4 or rex materials to a thin edge at 62 rc. you are asking for a chipped blade. Im gonna get blasted for this one I can feel it comming.
But we all have or own ideas about whats right and whats wrong. I just want to know what you see as the advanage? I have made MANY industrial thin blades. A2 is the steel of choice .. Try this take a hss drill bit grind it down in the middle to a thin section keeping it cool as you do . Put it in a vice with the thin part sticking out just a little .
TAP IT WITH A HAMMER. IT WILL BREAK IN A HEART BEAT.
Take the edge of a knife heat treated properly in a more common knife steel to about 58 rc. do the same . It will flex before it breaks.. The m2 or 4 or rex will
hold an edge for a long time .. but cpm420v or 440v and others will also . The alloys in it are tough. So 58rc a bit of spring and good edge holding or 62rc good edge holding and brittle?
There is also the heat treating concerns with the m series.
Thats your choice. 52100 is a great steel for this application also a2, 440v 420v if you want tough and spring.. Just my 2 cents worth..
 
Darrel, thank you for the great reply.

Broken or chipped knife blades are a real drag. I've made several larger knives from A2 and found it to be rather easy to grind compared to CPM 440V. I haven't tried 420V, but both these steels are almost 8 times more expensive than A2.

The A2 knives seem to have a great cutting edge and finish out lovely.

Hmmm. Maybe I'll stick with the A2 and D2 steels. I'll try and find some 52100 in plate or bar stock as well.

Do you think RC 58 is optimal for 440V and 420V?

Thanks again for the information. I really appreciate it.
 
Yes I do. 58 rc in my tests works very well.
The cost of a blade stell is a mute point. Quality is job one. ats at 9-15 a pound or cpm at 9- 15 a pound. A2 is not to bad..
Remember 58 on a2 is a good rc..%2100 if you find it let me know hahahah in flat stock..
Remember 52100 is a weird steel to get the grain tight in. It has to be shocked.
A2 is Tough and holds good edge.. d2 a great die steel.. not my fav for edge holding but is tough as nails..instead of d2 I would go to cpm stainless steels IMHO the best stainless I have seen for edge holding ..and grain refinment..
 
CPM 440V costs about $38 a pound here in Germany. And that's NOT precision flat ground, but rather rough plate. ATS 34 is almost impossiblr to find and is also super expensive. 154 must be ordered in 500 lb. lots... I made several knives from 440V which I'm selling at around $187 each and at that price am not making even the US minimum wage...

Have you tried BG-42? I think it's from Latrobe Steel in PA. but I haven't hunted up their address yet.
 
Yes on the bg42 I have been using it for a year or so. I like it alot also. The grain ia refinied much better the the ats34 I have used. It hold the edge a little better.. Most of all it does have the manufacutring problems I have seen with ats. Have you tried to find 440c there? Or o1 tool steel. Might help..
 
Hello Darrel,

440C isn't available here in Germany - at least I haven't been able to find it. It has a German material number, but no mill I've called has it in stock.

O1 is available, but I think A2 is a better choice for knives and I can get that here too.

I'm really thinking of going with BG-42 for the next batch of knives. I spoke with the mill that makes it in Penn. and they were very nice nice and helpful. If they come through with the amount I wanted, then I hope to have it here before Christmas.

What do you think is the best hardness for BG-42? I'd guess again at about 60 for knives with blades under 5 inches...
 
RC for knife edges 56-60 your choice. Most of the blades I do I run at 58. Its in the middel. I find the edge holding at 60 a slight bit better BUT the steel is brittle.
I would rether have a blade I can put a little side way flex to than a brittle blade. You choice. Try a sample of both.. Let me know what you find..
I work with bg42 all the time now. Its a good steel made well. I like it in place of ats34 ..

 
I hope the Latrobe guys are able to deliver at the price they mentioned.... I need plates rather than bar stock... I'm still gonna be looking at investing around $2000 in steel.... I hope Santa is very very good to me this Christmas.:)
 
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