ytuyuty Posted December 26, 2015 Share Posted December 26, 2015 Dumb newbie question, looking for confirmation I made a 1/8" thick knife blade out of a leaf spring. After quenching in oil, I wanted a differential temper. So I heated a piece of leaf spring and put the back of the knife blade onto the hot steel. I was looking for the change in colors across the blade, but the entire knife blade turned dark charcoal grey immediately. I didn't see any color changes develop across the blade. Does this mean that the hot leaf spring was too hot to effect a controlled differential temper? Does this I mean I overheated the knife blade to ~700 degrees almost immediately? I don't want to do anything else with the knife blade until I figure out what the hell happened. I assume that, next time, I shouldn't get the leaf spring so hot. Thanks Quote Link to comment Share on other sites More sharing options...
John McPherson Posted December 26, 2015 Share Posted December 26, 2015 Sounds like the chunk was too big for the blade, too hot, wrong position, or made too much contact. Or a combination of these. It is better to sneak up on it. Heat a small bar, say 1/2" square, to a dull red. The smaller bar can be made to conform to the back of any blade shape. Apply it to the back of the blade, with the tang clamped in a vise, edge down, so that you can see the colors run. Be advised that the colors will continue to run for a short while even after you pull the bar away. Have a plan to stop the heat with water or air if goes too fast. Practice on some scrap first. Quote Link to comment Share on other sites More sharing options...
ytuyuty Posted December 26, 2015 Author Share Posted December 26, 2015 Thanks Quote Link to comment Share on other sites More sharing options...
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