Abstract: A plunger for die casting may include a front injector end made of an iron alloy including, by mass: about 1% to about 6% nickel, about 0.1% to about 5% copper, about 0.2% to about 2.5% aluminum, about 0.5% to about 2% manganese, and about 0.05% to about 0.2% carbon. The iron alloy may be formed into an initial shape of the front injector end, heated to a temperature greater than or equal to about 900° C. and then cooled to form a supersaturated solid solution of iron and dissolved alloying elements. Then, the iron alloy may be heated at a temperature sufficient to precipitate intermetallic nanoparticles from the supersaturated solid solution to form an intermetallic precipitate phase dispersed throughout an iron-based matrix phase. A chemical compound layer may be formed at and along a surface of the iron alloy by exposing the iron alloy to an oxygen-containing and/or nitrogen-containing environment.

Abstract: A steel sheet used for hot stamping includes, by weight percent, 0.18˜0.42% of C, 4˜8.5% of Mn and 0.8˜3.0% of Si+Al with the balance being Fe and unavoidable impurities. The alloy elements of the steel sheet enable the actual measured value of the martensitic transformation start temperature after hot stamping to be ?280° C. The method for manufacturing the component includes: heating the material to 700˜850° C. and then stamping; cooling it to the temperature that is 150˜260° C. below the martensitic transformation start temperature by cooling in a die, cooling by air, water, or other methods; heating the component to a temperature ranging from 160 to 450° C. and maintaining the temperature for 1 to 100000 seconds for heat treatment, and then cooling the component to room temperature. The formed component has a yield strength of ?1200 MPa, a tensile strength of ?1600 MPa and a total elongation of ?10%.