Tried a coal forge for the first time after 6 years on propane, my steel did something weird

I finally got to use a friend's coal forge in Austin last weekend after doing everything on propane since I started. The heat came on way faster than I expected, and I normalized a 3/16" leaf spring blank before shaping. But when I quenched it in oil, I got this odd crack along the edge that I've never seen with my gas setup. Could the coal fire have caused uneven decarburization, or was my quench too late? Anyone else switch fuel sources and notice a difference in how their steel behaves?

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the_vera1d ago

That coal heat is a whole different beast, sorry about your crack.