Heat treat question.

First want to say hi to all. New guy here. Not sure if this is the right place but I have a heat treat question. I'm in a small, small shop with limited resources. I have made a small piece out of 1045 steel, 25mm OD, tapers to 7mm and 25mm long, I use to press sleeves into another part. The metal sleeve is also 1045. It has a .5 step and after a while the little step on the pressing part wears and gets out of shape. I'd like to harden it to last longer. As I said I'm limited on what I have available but we do have a set of torches here and wondered if I can use them to heat it up to a glowing red and then dip it in water . Would that give me some hardness or make it brittle? Thanks.

Yes, you can harden it with flame (bring it to the point where it stops being attracted by a magnet), but you need to do tempering to avoid excessive brittleness. Ideally, tempering is done at about 550-560F. Some household ovens can go almost that high, but if the part is not large, you may get by with using you torch to evenly re-heat the metal to dark blue color. Try to do tempering right after hardening to prevent cracks.

Water quenching is fine, but brine would be better for more even cooling. Expect some deformation (brine will lessen it a bit).

but brine would be better for even cooling

Click to expand...

Which means salt water

The salt reduces the generation of STEAM at the metal / quench interface

STEAM is just an insulator, interfering with the quench process

Thanks. That's very helpful. And I take it I'd temper or re heat after quenching it?

PDETRO said:

Thanks. That's very helpful. And I take it I'd temper or re heat after quenching it?

Click to expand...

To some temperature desired. Thumbnail is 4142 Mass Effect data which would be a little different from 1045. Note all examples on page 15 are quite high (1000-1200F) - meaning more TOUGHNESS and less hardness

The chart on page 14 gives other examples of tempering temperatures, and the temperatures at bottom relate to the hardness numbers at the top - in both Rockwell C and Brinnel

On Edit....The 1040 data say 42 Rockwell C at 700F, where the 4142 says 47 - as an example of the differences

which would be a little different from 1045

Click to expand...

They make preheat treated steels which would be ideal for your situation. It can still be machined with normal tooling, but will provide a much longer life for your tool.

Then you can read up on steels and heat treating and learn about that as a separate subject.

PDETRO said:

First want to say hi to all. New guy here. Not sure if this is the right place but I have a heat treat question. I'm in a small, small shop with limited resources. I have made a small piece out of 1045 steel, 25mm OD, tapers to 7mm and 25mm long, I use to press sleeves into another part. The metal sleeve is also 1045. It has a .5 step and after a while the little step on the pressing part wears and gets out of shape. I'd like to harden it to last longer. As I said I'm limited on what I have available but we do have a set of torches here and wondered if I can use them to heat it up to a glowing red and then dip it in water . Would that give me some hardness or make it brittle? Thanks.

Click to expand...

The SAE1045 lacks sufficient Carbon and is deforming because this steel cannot obtain the hardness required to not deform in service. I suggest changing to O1 oil hardening tool steel. Water hardening steel has a tendency to crack in heat treat with larger sections. If you want to use a water hardening steel SAE1090 would be a much better choice. Water hardening steel will provide a hard surface and a softer timbre inside. An oil hardening steel will harden deep. In either case the heat treat process is about the same. Water hardening quenching temperature is a little higher than oil hardening steels. I assume you will use a torch to heat the piece to quenching temperature. Try to heat as evenly as possible with sufficient time to heat thoroughly before quenching. Use a carbonizing flame. After hardening polish the part to remove the scale so that the color change during tempering can be observed. Temper to a light to medium straw color at the business end with the back end up to blue color. Then stop the tempering by again quenching. The straw color is about 55Rc and the blue 45Rc. Use care while tempering the piece. Us brine as a quench medium. The salt reduces the steam forming at the surface and the chance of cracking water hardening steel.



Comments?

All the best.
Roger