Senior Pre-hardened mold steel PX4, P20 improved varieties, PX4 by vacuum degassing process, a good degree of uniformity of organization, surface hardness of the center, respectively, compared with p20 and so improve the uniformity, the cutting and processing of mirror-grade material in 30hrc the most good. Its low sensitivity to weld cracking balance of ingredients designed to improve the weldability, has introduced even omit the preheating and post weld heat or only at 200 ℃ for, but also less prone to weld cracking. PX4 30-33HRC hardness of pre-hardened steel, engraved mold after processing can be directly put to use in well-designed manufacturing processes, to be quite uniform and Hardness to mirror polishing and etching processing of the fine; EDM the hardness of the surface hardened layer is low, easy to polish; low sensitivity to weld cracking balance of ingredients designed to substantially improve the weldability. Typical Applications: Suitable for general survival of large quantities of resin and plastic molds. Factory state: HRC30-33 hardness quenching: HRC52 main purposes: production mold with a large mirror, taillights, mirror shell, the front bezel, camera, household appliances, etc.