devencalcutt

Hey guys, Hopefully I am not going to upset anyone for the nature of my post, but I feel like this community would really be able to help me. I am brand new to the forum, partly because of a life interest in hand crafting my own knives/swords/tools, and partly because I work as a mechanical engineer at a plant that heat treats many automotive parts. I joined the forum because I stumbled upon it once before when I was curious about choosing a type of steel for a knife I was making for my father in law. I didn't join then but it was evident that you guys were knowledgeable in this field and for that reason I am back and seeking some assistance. I am not looking for help with knives this time, but in my job as the heat treating process is something common between my work and creating knives. What I am challenged with is at work we are having constant issues with oxygen "scoring" on the surface of our parts. This issue is costing the company (no joke) hundreds of thousands each year because we have to ship the parts off site to have them buffed free of the surface scoring and then shipped back before assembly. Obviously my interest as an engineer is to eliminate the need for this buffing process, but it is a difficult challenge... This is where I am looking for knowledge from those with more experience in traditional heat treating methods, who may know some trade secrets to reducing scoring on the surface of your parts. I should add in case I am using incorrect terminology that by scoring I mean a buildup of (what I guess is) carbon on the surface of the parts after heat treatment. The issue I face is this is not a typical heat treat process. The parts are moved into an induction coil's path on a revolving table. The induction head is them moved forward around the part, the part is raised to about 1100 degrees in 6 seconds, and then it is immediately quenched to reduce the temperature to around 200 degrees over about 10 seconds. Thus far, going by my own research and taking ideas from what others in the industry have been doing I have designed an "inert environment". This consists of a box that moves with the heating head around the part. The front of the box has a constant flow of water to create a waterfall over the front of the box, sealing the air inside the box. Inside the box a constant flow of 24 cubic meters/hour of nitrogen is pumped into the box in hopes to purge the oxygen out of the environment while being heated and quenched. The thing is, the box works. There is no scoring on the surface on my trial parts. My problem is that we run 6 of these heads, and anything less than the 24 cubic meters/hour of nitrogen still leaves scoring on the surface. As you can imagine, 144 cubic meters of Nitrogen per hour, 24 hours a day seven days a week is going to require a MASSIVE tank of nitrogen, plus it’s going to cost a bunch (not as much compared to buffing, but I hope for better) and we are going to have to fill the tank no matter how big on a frequent basis. It’s a pain really. What I come to you guys asking is for your thoughts on the process. Is there anything that you would criticize? Improve on? Try differently? It’s something that I have been working solo on for about 4 months now, and I'm scratching my head at what else I can try. My knowledge of heat treating comes from a long time welding, and that has just taught me that you need an inert gas to prevent contaminates from getting into your weld. Beyond that, I'm still learning. Any suggestions and tips would be graciously appreciated, as I think I need to look outside the box. Thank you for taking the time to read through this, and again I apologize if this post isn't something that is meant for this site, and in which case I would be more than willing to take it down. Thanks in advance. Deven.