Cast and Forge

Hey Forum, I think I forged about 12-15 hammers from 1045 yet and in the last months I have massive problems with them cracking during the quench. Picture 1-3 is the first hammer that cracked during the quench. I heard 3 times the horrific "ping" sound and here you go with a big crack right through the eye. Picture 4-5 is a rounding hammer that showed the same kind of crack as the first hammer. I heared no sound of cracking. I cracked it completely open to examine the grain and the crack itself. After this hammer cracked I assumed that I forged the steel too cold when drifting the eye. So I forged the next little 0.9 kg hammer a lot hotter. I will heat treat it the next week I think. What really confused me is the piece of steel in the last picture. I finished my guillotine tool today and tested it on this piece. Just a couple of heats and some hard hits with the hammer. After I finished I put the piece aside and shut down the forge. When I came back it wasnt red hot anymore but still hot (black heat). So I threw it in the water bucket to cool it down. After I looked at it I saw this big crack right through the fuller grove. Iam at a point now where I dont know what to do next. Nearly every piece of 1045 cracks (Iam glad the guillotine dies did not). I forge everything by hand so its really frustrating to see the hard work going to pieces in the quench. Any tips/suggestions? Those hammers are the first ones after changing from solid fuel to a gas forge. Can there be any connection to this? Iam thankful for every hint. Thanks Tim