1 Introduction M300 steel heat treatment, uniform hardness of 31-35HRC, workers molded never deformed, because the chromium content is higher than comparable other steels (16% Cr) so the corrosion resistance is very high. All general chemicals with corrosion resistance, suitable for the manufacture of transparent plastic mold, PVC plastic mold, this stainless steel is more action, it is easy to achieve the desired highly polished and mirror polished steel of the same title as the best quality. This steel is the same series of top products, the overall performance is good, high demand column of anti-acid mirror mold factory state line consideration: Pre-hardened to 1000-1100N / mm2 (31-35HRC) 2 heat treatment Forged: 1050 ℃ start melted down and forged to 850 ℃ slow cooling with the furnace. Annealing: 800-850 ℃ air cooling or furnace cooling to 600 ℃, hardness up to 285HB. Quenching: 1000-1050 ℃ is cooled by oil or air. Tempering: 600-700 ℃ or 170-210 ℃. [1]? Need to be tempered immediately after hardening, time at least 2 to 2.5 hours. Welding: welding but can be avoided if possible. 3 Use for exposure to chemical corrosion large, transparent plastic, camera lenses and other plastic mold steel more impervious to this effect, easy to reach and highly polished mirror finish required, the steel of the best titles of similar products Suitable for all chemical contacting the plastic mold, transparent plastic products, or mold erosion of the items.