Flame hardening 1045 steel

David J. · Jul 14, 2011

I have a few non critical parts that need one surface flame hardened.
Say 6-8 square inches maybe 20-30 thou. deep.
I have fast quench oil that I use on 4140...should i use the oil
or just dump the parts in water?
I have a pretty good idea of the results I get with 4140, will
the 1045 respond the same? The carbon is pretty close.
Thanks
David

gwilson · Jul 14, 2011

1045 is going to be a water hardening steel. However, it has low carbon,just about at the threshold of what will harden at all. It may just come out tough,like 4140.

Even if it does get hard,it will have poor wear resistance,and if a knife,won't hold an edge very well at all.

If the parts are just machine parts that need some surface hardness,it should be o.k.. The trouble with any water hardening steel,is that it will be the worst type of steel to deform,crack,or warp. Air hardening is the most trouble free in terms of keeping close dimensions,not warping,etc..

If tour pieces have holes drilled in them,stomp the holes as tightly with fine steel wool as you can with a flat nosed punch. This will keep the holes from developing cracks if they are near edges,especially. They used to put clay into holes for the same purpose,but the clay kept the holes from hardening inside them. Steel wool is better.

Brine hardening is better than water. Dissolve ICE CREAM salt(don't know why it's the best,but it s recommended) in water until a potato will float in the water. Brine helps keep a little layer of steam from forming around the surface of the steel. This makes hardening more even.

Heating the steel evenly is also very important. It is best to use a furnace if you can,rather than a torch. Even heating helps reduce the warping during the quench.

johnoder · Jul 14, 2011

Commercial flame hardening generally is mechanized with a water spray following the heating torch. Depth is controlled by heat input and rate of travel. 3/16" deep is not uncommon.

As an interesting aside, down hole oil tool companies I have worked for quenched long heavy 4142 solid bars with water spray as they exited from a conveyor equipped in-line furnace. Almost all suffered some minor spalling on ends, and a few split right down the middle.

J.O.

David J. · Jul 14, 2011

Thanks Guys
The customer just brought 1060 steel instead....what do you think
stay with water or go back to quench oil. Again, these are not
critical and only need the surface hard.
It's going to be a torch job.
David

DaveE907 · Jul 14, 2011

6-8 square inches on what sort of part configuration? If the part has any real mass that's a tremendous area to bring to critical temperature and maintain it there prior to quench. 1060 will flame harden well by traditional means.

As John described, water is the quenchent used for flame hardening in production, oxy-fuel flame(s) immediately preceed the water as the workpiece typically traverses the heating and quenching zones. The zone heated to critical is a small area directly under the torch(es), it immediately moves to quench in a continuous process for area flame hardening.

gwilson · Jul 14, 2011

I repeat,ANY plain carbon steel is hardening. On the 1060,the first 1 means iron. The 0 means no other alloys. The 60 means .60% carbon. That means a plain carbon steel with .60 carbon in it. I use W1 a lot,which is aprox 1095,can be a little less or more carbon.

If I make a letter stamp from it 1/4" square and 2" long,I cannot harden the whole 2". It usually splits open. I just harden 3/4" of the business end. Treacherous stuff.

SAG 180 · Jul 14, 2011

I've been playing round with hardening some 1045 recently. I'd cut some discs off the ends of 80mm diameter bar stock about 20mm thick. I'd heated the discs with two blowtorches, one on each face to just barely get to an orange heat in low light and it took a long time to get there.

I used some zirconium refractory wool to rest it on for insulation which helped a bit. After dipping in straight cold water while moving it rapidly round to help shed the steam bubbles it tested fairly hard with the simple tests I could try but with no tempering applied. Some online data sheets for 1045 mention tempering flame hardened 1045 steel at only 180 deg C ( Eagle and Globe ).

There was a soft zone where the tongs I used hindered quenching so the next sample used a 1/8" wire frame to hold and quench which worked fine. An old hammer marked "50-57 Rockwell C" was dented by hitting the sample very hard and took on an impression the power hacksaw marks still present on the sample.

The only sample of 0.6% carbon steel I tried so far was a 6" long bar of 2" by 1/4" spring steel which I wanted glass hard as a backing plate for a sander and I water quenched it even though it's an oil hardening steel according to the springworks. As it was dipped into the water one flat side first, it bent 1/4" like a banana and after grinding one end a crack through the core was visible. I'm certain that uneven heating and quenching was the cause

David J. · Jul 14, 2011

They are just wear pads .75 x 2 x 4 in. with 4 blind tapped holes
1/2 in deep in the back side. Only need the surface hard.
Plan is to bolt them to a long piece of 1 in thick scrap, cook them
with a rosebud and water quench. Pretty sure I can get the
whole surface above critical temp in one shot.
Thanks
David

jdj · Jul 14, 2011

Interesting. I was thinking of trying to flame harden a flat area of 5/8" width by 2.5" long on a 2" diam. bar of 1045. To keep set screws from marring it TOO badly, over time. I only need that surface hardened, doesn't have to be deep.

Jeff

johnoder · Jul 14, 2011

Have some 1500/1550 degree tempil sticks on hand if they make such things. Getting them too hot and heating them too long will just decarb the surface you are trying to make hard. Shoot for a slightly carbonizing flame (tending towards yellow) on the rosebud to help counteract this.

J.O.

gwilson · Jul 14, 2011

You can also put them in a stainless steel envelope with Kasenit to add to the surface carbon. Plain charcoal is even better if you have a cast iron container with a lid. I do this in an electric furnace.

technocrat · Jul 14, 2011

johnoder is right about not overheating the part. If you don't have temp sticks, try a magnet. Steel becomes non magnetic when heated, called the critical or Curie point, at about 1400 degrees.

At the Curie point, the steel is transformed into Austinite and quenching preserves the structure. Tempering transforms some of the Austinite into Martensite and reduces the hardness.

I use a really strong rare earth magnet, you can feel the pull from a distance. Be careful, last thing you want is a lump of hot metal rapidly approaching the magnet in your hand!

gwilson · Jul 14, 2011

And,heat will demagnetize your magnet. Try to keep contact with hot steel quick and brief!!

HuFlungDung · Jul 15, 2011

Heating one side of a flat bar and quenching in water sounds like a recipe for making a shallow angle boomerang.

Can you not buy some quenched and tempered plate like AR400 or some such designation?

gwilson · Jul 15, 2011

Sag: 1060 backing plane for a belt grinder is not going to last. Not enough carbon to have decent wear resistance. What I have used is A2. I drilled and countersunk a screw hole into each corner for flat head screws. I fully harden the A2 in AIR and leave it fully hard. I screw it over the cast iron platen. When it wears,I can turn it over.

D2 would be even better,more wear resistant,but the A2 has stood up pretty well.

dsergison · Jul 15, 2011

how about torch hardening 1018 with "cherry red" brand kasenit type stuff?

any particular precautions or recomendations? I did one part already, water quenched. it got somewhat hard. really poor color consistency. was only looking for some wear resistance improvement.

David J. · Jul 15, 2011

Well it seems to have worked ok. As mentioned I have done this with
4140 and 4150 using oil quench in the past , just had not tried it
with 1045 and 1060.
The big rosebud managed to get the whole surface up to temp
( judging by color and the magnet ).
Again this was not a real important part.
I don't have a hardness tester but can report that a plain old HSS
1/8th in drill bit won't cut into it on the hardened surface but
will still drill the back side. Polished them off with scotchbrite
and didn't fand any cracks.
Thanks for the ideas.
David

lazlo · Jul 15, 2011

I just water-quenched a 1045 hammer I forged last week.

Nothing complicated: 2" 1045 bar stock, forged square. Slowly heated to non-magnetic, and then quenched in water.

It skidded a fresh file no problem -- it was definitely hard.

I tempered it with an acetylene torch on the eye until the main body was violet, and the hammer face and peen were light silver-straw. Ran a hardness testing file across the face and it was above 50 Rockwell.

Benesesso · Jul 15, 2011

technocrat said:
At the Curie point, the steel is transformed into Austinite and quenching preserves the structure. Tempering transforms some of the Austinite into Martensite and reduces the hardness.

Er, the purpose of quenching is to preserve the austenite phase down to the Ms point (martensite start). Further cooling then transforms all, or nearly all of the aust. to mart. (full hard/Mf-mart. finish).

Tempering reduces the mart. hardness but increases toughness without any phase changes.

JST · Jul 15, 2011

If you are worried about the magnet. get one that is generally cylindrical with the ends the poles. Stick one end of it to a suitable length of 1018, and you will find the far end will be attracted to steel.

Now you have a "remote magnet" that will show the curie temp, but will not require your delicate pinkies to be near the hot material.

Flame hardening 1045 steel

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