Composite exothermic agent for alloy tool steel

The invention discloses a composite exothermic agent for alloy tool steel. The exothermic agent is prepared by processing the following raw materials expressed in weight percentage: 14 to 22% of magnesium powder, 9 to 11% of potassium nitrate, 22 to 30% of fly ash, 10 to 21% of iron oxide powder, 20 to 25% of fluorite powder and 6 to 10% of acidized graphite, wherein the fly ash is obtained by successively placing calcinated fly ash in sulfuric acid with a concentration of 20 to 25% and in a sodium hydroxide solution with a concentration of 16 to 24%, carrying out stirring for 20 to 22 h, filtering the fly ash out from acid-alkali leaching liquid, flushing the fly ash with deionized water until the fly ash is neutral, testing the pH value of the fly ash with pH test paper so as to confirm the pH value of the fly ash and carrying out filtering and drying. The composite exothermic agent for alloy tool steel produced and developed in the invention overcomes the disadvantages of powdery exothermic agents.