Need heat treat advice on machined part

[godogs57]

I have a friend that dropped this part off and asked me to ht it for his factory. It is a gizmo that is A2 steel, and it 1 1/8" thick, 3" x 2 1/2" in length and width. As you can see, it has some drilled holes and some millwork in it.

I have never heat treated A2 steel and from looking on the internet charts they say to heat to 1750-1800 degrees and hold for one hour per inch of greatest thickness. They also say "protect the steel by packing with inert material packed in containers" Huh? Also says to temper for an hour at 350-400 per inch.

If I wrap it in foil like I do my blades and go with 1750 for an hour will I be OK? Is an hour too long?? Seems like a long soak to me.

Any suggestions appreciated, as I only ht CPM154, some 440C in addition to the forged stuff.

Thanks,

Hank

Here is the part:

 

[mete]

The Crucible website [www.crucibleservice.com] says 30-45 min which is reasonable .Do the preheat steps . For the quench immediately remove from foil and air cool.Temper 2+2 hours.Hard to give further details without knowing details of application.If you've done 154CM this should be no problem. I don't know if plate quench would be applicable.

 

[Nathan the Machinist]

Stuff like that isn't too bad.

I used to use argon in my oven during heat and a fan and wire mesh for quench. That was before I got into making knives. I have started using foil and plate quench (steel plates) on flat stuff like that and I get less scale. I quench in the foil when using plates. Be sure to put the seam on the edge where it won't get between the part and your plates. You would need heavier plates than you would need for a blade.

It takes a while to get to temp when it is thick like that. So I'd say let it soak an hour once your oven reaches temp to be sure you're getting 45 min of austenitization.

The part is going to change dimension from HT - they need to accept that it is unavoidable. But there are austenitization temps and tempering temps that can minimize it. Some parts shrink, some parts grow, some parts do both. Most part warp, at least a little.