Todays Project - What did you do today?

[Highpower]

(01-02-2016, 08:00 PM)TomG Wrote: ....Was it 4140?

Tom

Yes Tom. 4140 annealed. I used 4140 HT as-is for making the arbor/broach bushing. The process I used was to put the part in the (cold) oven and pre-heat to 1200° F then soak for 15 minutes to let the material get fully saturated. Then set the oven to 1575° F and again let it soak for another 15 minutes after the oven reached that temperature. The thickness of the ring is only 3/8" roughly.

I pre-heated the quench oil to 130° F before I did the quench. Kept it stirring around in the oil watching the red ring turn black, and a few seconds later the crust exploded off of the ring (in slow motion... ) and sank to the bottom of the pot. The ring came out of the pot about 95% clean. Very little black scale remaining and came off quickly and easily with a stainless toothbrush.

No engineers here and I couldn't really decide how much to draw it back, and I just tempered it at 575° F for 30 minutes. According to my highly calibrated Japanese hardness testing files I'm estimating about 53 - 54 HRC after the tempering.

Now this is the point where an engineer is going to come along and tell me that is too hard for that part, right?
And that would be fine with me. I could always do a second tempering later...