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snowman
04-23-2005, 12:35 AM
I've made a couple hammer dies for doign jewelry work. They'll work mostly on silver, but some steel.

I need to harden them.

Material is 4140.

What should I be shooting for? thru harden then what Rc?? Just trying to determine my temper temperature.

What kind of oil....i've heard people suggest hydraulic...does it work OK?

-Jacob

Jpfalt
04-23-2005, 01:41 AM
With 4140 you will peak out somewhere around Rc58. I have quenched in used engine oil, new 30WT, hydraulic fluid and saw bar oil. The only one that didn't work was the saw bar oil if it wasn't dead cold. Don't forget to temper at about 475 dF which will retain most of the hardness, but will significantly reduce residual stresses and increase toughness.

precisionworks
04-23-2005, 08:50 AM
Heating at 1600 F followed by an oil quench will harden the 4130 alloy. Final hardness is limited to about 52HRC. 4130 is tempered at between 750 F and 1050 F, depending upon the strength level desired. The lower the tempering temperature the greater the strength.

The best quenching oil is..........quenching oil! This is specifically formulated for heat-treat use. They are rated slow, medium or fast. Here's a table from Shell Oil: http://www.shell-lubricants.com/Metalworking/tables/quenching.html

In a pinch I've used motor oil. Stinks to high heaven, makes everything in the room greasy, probably provides rust protection too <LOL>.

A2, D2, or just plain O1 will give longer tool life (higher hardness). They are often used for cold extrusion punches, essentially what you're doing.

------------------
Barry Milton



[This message has been edited by precisionworks (edited 04-23-2005).]

ibewgypsie
04-23-2005, 10:22 AM
Which brings me to a point, I have a six foot x 4" x 3/4" bar of D2 I can not cut. The portabandsaw just squeals like it is calling dolphins.

Should it be annealed in Alum? (surface?) or fire baked and buried in ashes?

precisionworks
04-23-2005, 10:43 AM
D2 is a pain on the bandsaw. It work-hardens as it's cut, which puts tremendous stresses on your saw blade teeth. Also, it smears, increasing friction as the blade passes through the stock. Its rough surface finish compounds blade wear.

Most of the tool & die shops around here have switched to carbide-tipped blades. They tell me that on D2 the blade life is twice as long, and they can cut about 25% faster.

------------------
Barry Milton

snowman
04-23-2005, 09:45 PM
quenching oils are rated for a temperature. can someone describe this? specifically, they say temp is 130 degree or something...dont know what that means.

how long should i soak at 1600? 1 3/8" diameter, 2" long.

what will drawing it out to 475 get the hardness down to?

-Jacob

precisionworks
04-23-2005, 11:34 PM
General rule on heat soak is one hour per inch thickness.

Tempering 4130
450F = 52HRC
550 = 48
650 = 45
750 = 42
850 = 39
950 = 36
1050 = 32



------------------
Barry Milton



[This message has been edited by precisionworks (edited 04-23-2005).]

Your Old Dog
04-24-2005, 12:07 AM
You might try a test piece using 30 weight non-detergent parafin base motor oil such as Pennzoil or Quaker State.

I heat treated chisels by filling a chicken noodle soup can with the oil at room temperature and then sinking the chisle down to within 1 inch of the bottom. Now, if you don't swirl it around, it develops a hot layer of oil around the chisel and it's self annealin. Take them out, touch them up on a stone and they cut very well. It was nice not to have to go thru the tempering process. If you're just using them for silver fabrication you may not have to get any more complicated than that. I've worked silver with a table spoon!

When you do the heat soak by 1inch cross section it means the thinnest part. So my S5 tool steel chisels only had about 1/8th inch cross area at the tip so I only had to hold them cherry red for something like 3 minutes before the quencing if memory serves me.

[This message has been edited by Your Old Dog (edited 04-24-2005).]