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Heat treating AR400


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Gentlemen...I have a problem that I as a very new Smith need ur expertise with...I forged 3 hand axes/tomahawks and thinking that I had a good hard base material I used AR400....the axes themselves turned out beautifully....after I polished them I heated them to critical temperature and quenched them in motor oil...the result was disappointing...while there was a change in hardness(the metal went from a dull clunk when tapped to a glassy ring...when I checked the hardness with a file..the file did skate off for a little bit but did eventually bite into the steel...after I did some research..which I definitely shoulf.habedone beforehand...I discovered that ar400 is considered a low carbon steel and is not suitable for tool making...but since I have already invested considerable time in the making of the axes I was wondering if there is some way to salvage the situation and make a usable tool out of them...20211128_165152.thumb.jpg.ae08ea7c525826a25a1fd12c218e2308.jpg

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1095 (and many other alloys), yes. AR400 (and many other alloys), no.

Technically AR400 isn't a specific alloy. I believe different manufacturers have different specs for the composition.

Like TP mentioned, quench a test piece of approximately the same cross section before you quench the axes.

Also, you would want to normalize not anneal.

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Experience like these teach the "Scrap Steel Rule":   *test* before using!

You could also try a brine; "add enough salt until it will float an egg" was an old recipe for a brine quench.  Again dangerous for a HC alloy.

If you bought new motor oil---you would have done better to buy new cooking oil!  (And preheat before using.)

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so i normalized and reheated and quenched in a extreamly salty brine and i have to say..was a significant improvment over the oil quench...so now i have another qustion....since the steel is not hard enough for optimal performance is it nessasary to temper the axes....wouldnt that soften the steel a little bit.....and reduce the edge holding caapabilitys?

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What did your test coupon tell you about needing to temper?

Haven't several people suggested you make and test representative coupons already? I know this involves you actually DOING tests yourself but if you won't folks will start losing interest in answering your questions. DOING research and tests are pretty  integral to successful blacksmithing, especially bladesmithing.

We answer questions to help people DO things, not so much to help them avoid doing things.

Frosty The Lucky.

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On 12/5/2021 at 1:27 PM, HUTT SMITH said:

so i normalized and reheated and quenched in a extreamly salty brine and i have to say..was a significant improvment over the oil quench...so now i have another qustion....since the steel is not hard enough for optimal performance is it nessasary to temper the axes....wouldnt that soften the steel a little bit.....and reduce the edge holding caapabilitys?

There is another option for making them have better edge retention.  You can weld high carbon steel to the bit area.  This could be done by forge welding or electric arc - as long as you get full penetration welds. Beveling the edges to be welded and welding from both sides has worked for me with other projects.  Of course then you have to clean up the welded area and then go through the heat treating steps for the alloy that you weld on.

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