Spring Tempering Methods

[Bo T]

Of course, in this case lime might refer to ashes, allowing the spring to cool slowly from temper. Wood ashes are occasionally used to (sweeten?) the soil.

 

[LRB]

Dang it Zonie, you've made me thirsty, and it's only 7:12 AM here.

 

[Loyalist Dave]

Wick are knife blades tempered at lower temperatures? I thought 450 was good for a knife blade tempering? Is that because they are stiffer than springs, which need the 750 degree mark?

LD

 

[LRB]

Hi Dave. That would be a yes, and another yes. Ideal knife blade temper will vary slightly from steel to steel, and sometimes the intended primary use of it. A 450°F blade temper would be reasonably safe with most simple knife steels, but not necessarily the ideal temper heat, depending on the above. 450° might be a good temper for 10xx steels, but a lower heat of 400° to 425° would be more ideal for 01 steel, which has added alloys to be dealt with. The ideal temps for general use are based on a good balance between hard and tough properties. Temper a blade of say, 1080 steel, at 500°, you will have a tougher blade, but will sacrifice a little in hardness and edge retention. Do the same with 01, and you lose on edge retention, but gain nothing in toughness. 01 has about a perfect balance with a 400° temper, or even just a tad under 400°. I prefer to go for 425° with 01, just to make it slightly easier to sharpen. One final point, recommended temper heats are based on tempering fully hardened and prepared steel.

 

[Zonie]

I think the moral of the story is, knife blades are designed to hold an edge so, hardness wins out over toughness.

Springs on the other hand are designed to bend repeatedly without breaking so toughness wins out over hardness.

That would explain why a knife might be tempered at 450°F which leaves a lot of hardness while a spring might be tempered at 750°F which removes more hardness but leaves the toughness to keep the spring from taking a permanent bend.

 

[jmforge]

1075 is good, 1084 would be a tad better as it typically has more manganese and is a tad deeper hardening and as such, less sensitive to quenchant speed. Canola oil heated to about 130F should work fine. 1095 is NOT a good steel for beginners using primitive HT setups because is is a very shallow hardening steel.

 

[Loyalist Dave]

1095 is NOT a good steel for beginners using primitive HT setups because is is a very shallow hardening steel.

Not good for either knives or springs, or just springs?

LD

 

[LRB]

1095 is one of the more difficult steels to heat treat properly. Especially in regards to knife blades. To be ideal it needs a tightly controlled heat for a five to 10 minute soak time at the quench temperature, and it requires a very fast cooling quenchant. To be right, and at it's best, the quenchant must cool the blade from 1475° to below 900° in about .6 of one second. Give or take a couple of tenths. Only brine will do that, but carries a risk of the blade cracking, so the next best is a commercial fast cooling oil, with canola oil bringing up the rear as a barely acceptable third place choice. As far as springs, I have made a few from 1095, but would rather use 1075/80/84. Much easier to work with, and much more suited to simple or primitive methods. In knife blades, 1084 is an excellent knife steel, very nearly as good as 1095, but is much more respondent to simple HT methods.

 

[Loyalist Dave]

Ah thanks for clearing that up.

LD

 

[M. De Land]

Wick, would 1095 quench properly in brine with a tight stainless foil wrap left on?
I use the wrap for gun parts made of A-2 and got to wondering if it possible to do a bit of cross technique on carbon steel.
Guess I could give it a try and see for myself.

 

[jmforge]

Not likely. Use some kid of thin anti-scale coating instead. Thin Satanite "mud" will work in a pinch.

 

[LRB]

I agree with Joe on a coating rather than foil. I use ATP-641 on my 01 steel, but even then that may slow it down too far to be at optimum with 1095. Most of the ATP pops off when it goes into the quench, but not all of it, all of the time. I kinda suspect that going into brine, it may all pop off. As you said, you will just have to try it.

 

[jmforge]

Wick, we HOPE that it all pops off so we don't have to mess with it. :grin: