4140 pre-hard

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a41capt

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I hope this is the right portion of the forum for my post, if not, please forgive me!

I had a need for 4140 pre-hard and thought I had found a chunk on eBay, at least that’s what they listed it as. I’m quite a newbie when it comes to steel composition, and when the piece arrived, it is marked A2 tool steel.

Is it 4140 as I ordered, or an entirely different animal altogether?

Once again, sorry if this is misposted, and please excuse my ignorance when it comes to the various steel forms.

John W
 

danallen

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4140 and A2 are quite different. The only way to be know what you received is to spark test it and compare it to pictures of both materials being tested.
 

a41capt

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Thanks for the quick reply. I included a typo in my original request in that I typed A2 but I meant D2. Still not 4140 HT though I guess…

Thanks again!
John W
 

trlvn

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An aside, but my impression is that D2 would typically be a fair bit more expensive than 4140. No? Maybe somebody with good 'McMaster-Carr' fu could verify?

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Quickie answer:

For a quick test, if you can slice off a small piece of the suspect material and heat it to a nice glowing red that a magnet won't stick to then let cool in still air. D2 tends to need an inert atmosphere for pro grade heat treat but don't sweat it for this. Once cool, if a file skates over the material, it's A2, D2, or some other air cooling tool steel. If it cuts, maybe with some effort, it's probably 4140 or some other low carbon steel. 4140 requires quenching so will be almost completely annealed when allowed to slowly cool in air. Brush off any scale before trying the file, scale tends to be silly hard on almost all steels.

Details for the metallurgically curious:

D2 is an air hardening steel. It is often used in die fabrication as it is very wear resistant. It holds a good edge in places where you need an edge (knives, some dies), but isn't very tough. It will chip fairly easily under a hard impact. Lovely for a small knife, pretty lousy for a camp ax, hammer, or large framing chisel. It's sort of like A2 in working characteristics.

D2 has higher carbon, vanadium, and chromium than A2, and lower manganese. Both steel have overlapping ranges for silicon and molybdenum.

D2 is stronger, polishes better, wears better, and corrodes less compared to A2. A2 is tougher. I like A2 for things like shop made gear cutters and fly cutters, where the cutting edges sees a lot of impact in use.

4140 is a low alloy steel, very tough, hardness maxes out around 58C in theory, although most charts show it maxing out at around 40C. Prehard is usually delivered at around 30C hardness. I've seen it used in firearms receivers, where you want need to balance wear resistance and toughness, but don't need a high hardness knife sharp edge for cutting or shearing. 4140 is a good steel for forging, and tends to behave nicely when quenching, unlike some stuff that wants to turn into a pretzel when it hits the quench. It has around 1 percent manganese and chromium, around 0.25% molybdenum.

These are all nice steels, but as you suspect, they are each quite different animals.

Maybe more than you wanted to know!

Cheers,
Stan
 

a41capt

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7C8608EF-1FBF-4AF4-A8FA-F58CEB924B46.jpeg

I must’ve selected the wrong material when I ordered it. These were both by the same seller, and I meant to order the 4140 HT. As for the price, the D2 is slightly cheaper from this vendor.

Thanks to all!
John W
 

a41capt

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Quickie answer:

For a quick test, if you can slice off a small piece of the suspect material and heat it to a nice glowing red that a magnet won't stick to then let cool in still air. D2 tends to need an inert atmosphere for pro grade heat treat but don't sweat it for this. Once cool, if a file skates over the material, it's A2, D2, or some other air cooling tool steel. If it cuts, maybe with some effort, it's probably 4140 or some other low carbon steel. 4140 requires quenching so will be almost completely annealed when allowed to slowly cool in air. Brush off any scale before trying the file, scale tends to be silly hard on almost all steels.

Details for the metallurgically curious:

D2 is an air hardening steel. It is often used in die fabrication as it is very wear resistant. It holds a good edge in places where you need an edge (knives, some dies), but isn't very tough. It will chip fairly easily under a hard impact. Lovely for a small knife, pretty lousy for a camp ax, hammer, or large framing chisel. It's sort of like A2 in working characteristics.

D2 has higher carbon, vanadium, and chromium than A2, and lower manganese. Both steel have overlapping ranges for silicon and molybdenum.

D2 is stronger, polishes better, wears better, and corrodes less compared to A2. A2 is tougher. I like A2 for things like shop made gear cutters and fly cutters, where the cutting edges sees a lot of impact in use.

4140 is a low alloy steel, very tough, hardness maxes out around 58C in theory, although most charts show it maxing out at around 40C. Prehard is usually delivered at around 30C hardness. I've seen it used in firearms receivers, where you want need to balance wear resistance and toughness, but don't need a high hardness knife sharp edge for cutting or shearing. 4140 is a good steel for forging, and tends to behave nicely when quenching, unlike some stuff that wants to turn into a pretzel when it hits the quench. It has around 1 percent manganese and chromium, around 0.25% molybdenum.

These are all nice steels, but as you suspect, they are each quite different animals.

Maybe more than you wanted to know!

Cheers,
Stan
Thanks for the education Stan, no explanation, no matter how lengthy is wasted on me! You’re right, I am making a small part for a pistol that’ll need some decent wear resistance. It’ll be a locking block for a Glock 19, and yes, I know I can just buy one, but where’s the fun in that!

John W
 

awake

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Yes, totally different. If I recall correctly, D2 is an air-hardening steel with extra toughness - ? something like that. Really nice tool steel. It should be received in an annealed state; machine and harden according to very exact specifications ... but at least with A2, I have been able to harden successfully even with my much-less-than-scientific home-shop equipment. I love working with A2, and I think D2 may be similar to work with ... but take all of this with a grain of salt, as I'm going by fuzzy memory with respect to D2.

On edit: I see that Stanstocker has given a much more accurate picture of D2 - higher wear, not higher toughness as I had vaguely remembered.
 

awake

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Thanks for the education Stan, no explanation, no matter how lengthy is wasted on me! You’re right, I am making a small part for a pistol that’ll need some decent wear resistance. It’ll be a locking block for a Glock 19, and yes, I know I can just buy one, but where’s the fun in that!

John W
My philosophy: never, ever buy something for $1 that you can instead spend $10 in time and materials to make!

:)
 

Rocket Man

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I hope this is the right portion of the forum for my post, if not, please forgive me!

I had a need for 4140 pre-hard and thought I had found a chunk on eBay, at least that’s what they listed it as. I’m quite a newbie when it comes to steel composition, and when the piece arrived, it is marked A2 tool steel.

Is it 4140 as I ordered, or an entirely different animal altogether?

Once again, sorry if this is misposted, and please excuse my ignorance when it comes to the various steel forms.

John W


If you need metal order it from Tennessee Die Supply, Nashville TN.

When I need metal I call them and order the size pieces I need cut to the size pieces that I need. They give me the price that includes UPS shipping to my house front door. I give them my card number then the metal arrives in about 3 days. They also sell, taps, bolts, ejector pins, everything needed to do machinist work. Some metals come in bars 3 ft long sometimes its best to buy full length if you have a need for the extra metal.

After I retired I moved from TN to Phoenix AZ area it cost less for me to order from TN die supply than it did to buy from a local metal supply company in Phoenix AZ. Prices in AZ are double the prices in TN that made UPS shipping the best deal.

Pre heat treated 4140 is tricky to machine if you machine it too fast friction heat causes the metal to get harder. Maybe you received pre heat treated 4150 not 4140.
 
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a41capt

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If you need metal order it from Tennessee Die Supply, Nashville TN.

When I need metal I call them and order the size pieces I need cut to the size pieces that I need. They give me the price that includes UPS shipping to my house front door. I give them my card number then the metal arrives in about 3 days. They also sell, taps, bolts, ejector pins, everything needed to do machinist work. Some metals come in bars 3 ft long sometimes its best to buy full length if you have a need for the extra metal.

After I retired I moved from TN to Phoenix AZ area it cost less for me to order from TN die supply than it did to buy from a local metal supply company in Phoenix AZ. Prices in AZ are double the prices in TN that made UPS shipping the best deal.

Pre heat treated 4140 is tricky to machine if you machine it too fast friction heat causes the metal to get harder. Maybe you received pre heat treated 4150 not 4140.
Welcome to AZ Rocketman! I live in Camp Verde, just about the halfway point between Phoenix and Flagstaff.

Thanks for the tip on Tennessee Die Supply, I’ll look them up next time I’m shopping. I have a local scrap yard, but they’re stocked with lots and lots of mystery metal, so no hope there.

Once again, welcome to the Grand Canyon State where we cherish our freedom and independence.

John W
 
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I hope this is the right portion of the forum for my post, if not, please forgive me!

I had a need for 4140 pre-hard and thought I had found a chunk on eBay, at least that’s what they listed it as. I’m quite a newbie when it comes to steel composition, and when the piece arrived, it is marked A2 tool steel.

Is it 4140 as I ordered, or an entirely different animal altogether?

Once again, sorry if this is misposted, and please excuse my ignorance when it comes to the various steel forms.

John W
I purchase the small amount of metal I need from McMaster Carr. I have always received what I ordered. If I need a large quantity of metal I get it though my Son’s business.

Tim Meyer
 

Lloyd-ss

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A41capt,
A lot of good advice so far, but I will add my 2 cents.
I have used the pre-hardened 4140 from McMaster and found it to be a good material. Not too hard, fairly machinable, and decent grain structure (more like consistent structure throughout.)
But what I have started using more of is 1144 stress proof steel. It is tough and if you are making small parts, it doesn't bend and break like lesser materials.

I buy my materials almost exclusively from either Mcmaster, or OnlineMetals. Online has almost everything and the service is fast and the prices are reasonable. Go to the online site and look at the various material specs, particularly the tensile and yield strength. You will see that the 1144 stressproof is darn good (108ksi tensile and 90ksi yield), and no additional heat treating is needed. Plus, it is cheap. Online metals periodically has 10 and 15% off sales and I stock up.

If you want a pretty finish on it, get some Van's Instant Gun Blue. Follow the instructions and you will love it on the 1144.
 

a41capt

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A41capt,
A lot of good advice so far, but I will add my 2 cents.
I have used the pre-hardened 4140 from McMaster and found it to be a good material. Not too hard, fairly machinable, and decent grain structure (more like consistent structure throughout.)
But what I have started using more of is 1144 stress proof steel. It is tough and if you are making small parts, it doesn't bend and break like lesser materials.

I buy my materials almost exclusively from either Mcmaster, or OnlineMetals. Online has almost everything and the service is fast and the prices are reasonable. Go to the online site and look at the various material specs, particularly the tensile and yield strength. You will see that the 1144 stressproof is darn good (108ksi tensile and 90ksi yield), and no additional heat treating is needed. Plus, it is cheap. Online metals periodically has 10 and 15% off sales and I stock up.

If you want a pretty finish on it, get some Van's Instant Gun Blue. Follow the instructions and you will love it on the 1144.
Thanks Lloyd,

I’ll give the 1144 a look, and you’re right about Van’s. I’ve been using it for 20 years, and when applied to a warm piece in a dip tank (usually an appropriately sized piece of capped PVC pipe), the finish is as good as my typical hot water rust blue process, although probably not as durable.

For the occasional blue job, rather than going through the 12 to 20 steps of rust and card, it’s the right solution!

Thanks again for the info,
John W
 

Lloyd-ss

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We all have our favorite tool steels for one reason or another. I tend to make parts that need to stand up to abuse, so when necessary, I like to use S-7. It is a tool steel for chisels and such, a shock-steel. It will take an edge, can be tempered to a wide range of hardnesses, and can be hammered on. The one big drawback is that you have to send it to a heat treat house to be processed in an inert atmosphere so that it comes back to you scale-free. That's about $150 near me. More, if you want certs with it.

Here are a few of some little gizmos I made out of S-7 and had properly hardened and tempered. Tempering was done to achieve Rc 53-57. You can pound on them and they aren't fazed a bit..... unless you really go nuts.

original_e1195718-abd5-4d29-8e2d-7d9ef98f8edb_IMG_20221206_101835018.jpg
 

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