Just realized I've been forging my leaf springs wrong for years

I was working on a set of kitchen knives from a Ford truck spring, the usual 5160 stuff, and the edge kept chipping after the quench. I'd been heating it to a bright orange, like I do with mild steel, and quenching in warm canola oil. A guy at the Blacksmiths Guild meet in Boise last month saw me doing it and just said, 'You're cooking the carbon out.' He explained that 5160 needs a much lower heat, more of a dull cherry red, to keep the carbon in solution for the quench. I tried it on my next piece, kept it way cooler, and the difference was night and day. The blade came out tough and held an edge like a dream. I feel like an idiot for all the springs I've ruined. How do you all judge the right heat for different high-carbon steels when you're working with scrap?

2 comments

2 Comments

victor_hill705d agoMost Upvoted

That's a solid lesson learned the hard way. Honestly, a lot of us started by treating all steel the same. For scrap stuff, a magnet is your best friend. Once it stops sticking, you're in the right ballpark for high carbon, but you gotta watch the color like a hawk in your shop light. What's your shop lighting like, does it trick your eyes sometimes?

reesewilliams5d ago

My old garage's yellow bulb made everything look fifty degrees cooler than it was.