Thread: Quench metal by oxygen torch

Hello everyone
A while back I read an article in the home shop machinist magazine about making mild steel behave like high carbon steel. The author set out to see if appreciable hardness could be imparted to mild steel through heat treatment. The metallurgists, of which I believe the authors daughter was one, state that it isn’t possible. The article went on to do various things to the steel to harden it and armed with a Rockwell hardness tester the samples were tested. I cant recall everything they tried but the one system that had good results was what he called a super quench this was simply water with surfactants (dish soap) added to break up the surface tension and basically make the water wetter, this allowed it to cool the metal faster and apparently had the effect of making the metal harder. I was intrigued by this and tried an experiment for my self to see if it worked. I lacked any hardness testing equipment so I casted around trying to think of some way to test the samples, maybe an automatic center punch. I settled on something even less scientific then that, and made my samples from the same piece of cold rolled square bar and simply hit them against each other on there corners, to my surprise the quenched one sustained much less damage then the untreated one. I should mention you need to get the steel bright red before the quench. I haven’t used the technique in any real world situations yet but I think it’s a good trick to have in your back pocket. Try this for your self if you need to be convinced, I know the science says no but I bet there aren’t any scientists who have tried. I have wondered if one explanation might be something called carbon migration. If you have ever cut mild steel plate with a torch you will have probably noticed that the cut edge gets very hard, I needed to ruin a file to learn this for myself, I have read that this may be due to fact that the carbon in the steel surrounding the cut is drawn to the heat and therefore raises the carbon in the steel next to the cut to a level that would allow hardening to take place.
Darrell