tempering steel

[Rey]

I heat forge files to blazing orange to anneal, second I cut and shape to knife choice design,third I heat forge again to non-magnetic and quench in veggie oil to heat treat, then after it's cooled I clean it with conditioning belt by then the convection oven is 400 degrees hot, inside the oven it goes for 1 hour or until it turns a hay gold color for tempering. Would this be the process for files made in the usa or same as 1095 steel? Someone told me the process this knife maker goes by is he only heat forges the steel to blazing orange and quench in oil and it's done. According to him the knife comes out hard as tempered. Seems like a less time consuming but, I would like some input on this. Rey

 

[Doug Lester]

First of all, the using a blade as quenched will only work if the steel has something like 30-40 points of carbon which is marginal, at best, for making knives. Color is difficult to use to judge the temperature of steel by because it depends a lot on ambient lighting. It's best to test the steel with a magnet. As soon as the steel becomes non-magnetic heat it just a little brighter to austinize. BTW, you only touch the steel to or with the magnet; you can't leave the magnet in the fire for more than a couple of seconds or it could loose it's magnetism. Heating the steel to non-magnetic is not in itself suffecient, you also have to soak the steel to get the carbon back into solution and this will require melting the carbides in the steel. Depending on the steel that you are using, that could be from something like two to ten minutes. At the same time you need to keep the steel from getting too hot a growing the "grain" of the steel which will weaken it. This doesn't even get into more complex steels like high temperature or stainless steels which are a whole differeent ball of wax. Four hundred degrees will be in the ballpark for most of the simple, spring, and tool steels but you will have to experiment to find the ideal temperature to yeald the hardness for the blade that you are making. Two cycles are pretty much minimum and three are better. This is to allow the retained austinite to convert to untempered martinsite and then temper the untempered martinsite. Soaking the steel in white vinegar overnight is an easier way to remove the fire scale from it, but do this after tempering.

What reading material do you have? Pardon me if I'm making a wrong assumption, but you sound like you need book learn'n. "The $50 Knife Shop" by Wayne Goddard is good for a newbie. "The Complete Bladesmith" by Jim Hrisoulas is a bit more advanced but also very good. The Web is a great source of information but it's drawback is that the information is not presented in a sequential orderly fasion. A good library is one of the best tools that a knife maker can have.

Doug Lester