It's been many years since I spent time in the old blacksmith shop but as I recall heating steel to cherry red followed by a quick quench in oil (for oil hardending steel ) or water (for water hardening steel) will harden the material. Tempering would follow the hardening process and involves torch heating the tang end of the tool and watching for color change in the material. Color varies from blue (hardest) to straw yellow (soft) but I believe this all depends on the amount of carbon in the steel.