Tempering threshold (≈300°F start of hardness drop-off)

Above 300 degrees, I'm tempering the steel. Steels will lose their hardness if you form martensite in the welding process and you then hold it at temperature for an hour or whatever. Once you get to about 600 Fahrenheit — at 300 you start to see a drop-off in hardness. So if this is 300 Fahrenheit, you actually will have enough time — this is probably log time as I've drawn this — you have enough time in here above what you would have if you were just letting it cool to room temperature. It's just cooling down and being quenched to room temperature by the steel.