Hammer hardening/tempering?

[dave in pa.]

Hello all,

How about your tips on hardening and tempering 4140 hammer heads?

Specifically your tempering colors as I'm using a coal/coke fire.

Thanks,

Dave

[anvil]

http://www.smex.net.au/reference/SteelColours02.php

here's a color chart. I recommend a free apk for android and iphone as a handy in depth reference for all steel specs.

"Heat treaters guide companion"

[Stash]

Hi Dave. A few years ago Nathan Robertson had a hammer making workshop for the PABA gang at Steve G's shop. What we did was normalize/ grind, heat to critical,water harden, and then set refractory blocks in front of the dragon's breath of a gas forge so only the eye area was being heated. We kept moving it around, till the face and peen were bronze and quenched it off. In  a coal forge I would probably do the trick of heating an eye drift hot and insert it into the eye, and watch your colors, reheating the drift as necessary. Seemed to work for us. Hope this helps.

Steve

[dave in pa.]

Anvil,

I have the chart but was looking for what color is working best for those that have used 4140.

BTW... What's an "app", I'm one of those dinosaurs that have a phone that ONLY makes phone calls.

Stash,

The bronze color has worked out? No chipping or cracking?

I had pretty much decided on using a heated rod through the hammer eye to get the needed heat.

Thanks all,

Dave

[stevomiller]

You can buy Tempil sticks that melt at different temperatures which is helpful if you don’t have temp control, or a thermocouple affixed to the hammers face with some heat transfer paste on it, or nonflammable grease.

The more alloying elements in your steel, or if not perfectly clean of oils, the more variation you will have in temper drawing colors.

Also, if available, a high temp oven is really nice especially with alloy steels. Unlike plain medium carbon steels, they do better with multiple longer tempering cycles, where as medium carbon steels can many times get by with flash or quick tempering cycles. I’m not saying the other methods do not work, just what is better and easier to get consistent results.

Be careful of “blue embrittlement” which affects many alloys, and the temps are different for each: you can research each alloys heat treating specs, try multiple sources. There are time when 100* higher temp will NOT make your tool tougher, but actually more prone to breakage.

YMMV,

Steve

[anvil]

Then either ask your kids to do it, or do a google search for " 4140 spec sheet". Or look under "heat treat forum" here and read the thread on it.

And you will find all you need to know about this steel. 

And have them on file for future needs.

[Stash]

Dave- no issues at all with the hammer. I can and have lightly dressed out dings with a file. Next time I see you I'll show you the heat treat app, just to make you drool.

Steve

[Ranchmanben]

I use 1045 but it’s treated similarly to 4140. Forge to shape, normalize, anneal, rough grind, harden in water then temper to a straw color. I use a heated drift to do my tempering. I’ve also read that some people have problems with 4140 cracking when quenching in water. 

[Mark Ling]

Yeah I have had problems with 4140 cracking quenching in water, I only use it on struck tools now, and use 1045 for hammers. Also after hardening 4140 you want to immediately temper it because the stress that is built up in it can cause it to crack after being hardened. I too use a heated drifts to temper my hammers.

                                                                                                                                                   Littleblacksmith

[maplebones]

On 9/22/2018 at 4:46 PM, Ranchmanben said:

I use 1045 but it’s treated similarly to 4140. Forge to shape, normalize, anneal, rough grind, harden in water then temper to a straw color. I use a heated drift to do my tempering. I’ve also read that some people have problems with 4140 cracking when quenching in water. 

4140 should always be quenched in oil.  It has alloys that make it more hardenable than 1045, meaning it hardens deeper, but that's not required in a hammer. Neither steel is great for hammers. They can attain sufficient hardness, but have poor wear resistance. Plain high carbon steels like 1095 or W1 at around 1% C will harden 1/4 " deep with a tough core that is twice the strength of the core of 1045. with a wear resistant case. Anvil faces, which are essentially hammers, have always been made from high carbon steel because of it's abrasion resistance. I don't where the recent trend to using medium carbon steel for hammers came from, but they don't make a quality hammer.  

[JHCC]

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