Research progress on heat treatment of mold materials and molds in China
In the 1950s, all of China's mold steels were attacked by foreign steel grades. In the 1960s, in order to save raw materials and improve the accuracy of blanks, there was a rapid development of less cutting technology and precision forming technology. In order to improve production efficiency, many high-efficiency pressure processing equipments were used, and forging hammers were gradually replaced by presses. The performance of the original mold steel often fails to meet the high performance requirements of the service conditions, affecting the service life of the mold and the promotion and application of new equipment and equipment for pressure processing. At the end of the fifties, China's cemented carbide has developed rapidly, and a variety of steel-bonded cemented carbides have also been developed, which have achieved good results as molds. Since the 1960s, with the support of relevant state ministries and commissions, Chinese scientists and technicians have developed a number of new mold steels based on national conditions. Some of the new steel grades with excellent performance and good process performance have been adopted by mold manufacturing and use units. welcome. During this period, some foreign-used steel grades were also introduced, some of which passed the production trial and achieved good results. For some cold-working die steels and hot-working die steels with good effect, the relevant departments have separately organized performance comparison experiments and put forward suggestions for selection and application. To meet the needs of high wear and long life molds. At the end of the 1970s, the use of precision and large-scale engineering plastic products became increasingly widespread. The demand for steel for plastic molds increased sharply, and new requirements were placed on the performance of plastic mold steels. This paper is divided into six parts: cold work die steel, hot work die steel, plastic die steel, hard alloy and steel bond carbide, mold heat treatment, prospects and recommendations. Cold work die steel, the cold work die steel commonly used in China is still the old steel grade of low alloy tool steel CrWMn and high carbon high chromium tool steel Cr12MoV and Cr12. CrWMn steel has proper hardenability and wear resistance, and heat treatment deformation is small. However, CrWMn steel needs to control the cooling rate more strictly after forging, and adopts appropriate heat treatment to make the carbides have uniform and fine granular shape and are distributed on the substrate. Otherwise, it is easy to form a network of carbides, resulting in chipping and cracking of the mold during use. High-carbon high-chromium tool steel has high wear resistance, but its carbide segregation is more serious, leading to a decrease in directionality and toughness of deformation. The degree of segregation can be improved to some extent by repeated dialing. In 1981, China introduced the international high-carbon high-chromium tool steel D2 (Cr12Mo1V1). Compared with Cr12MoV steel, the carbide segregation of D2 steel is slightly improved compared with Cr12MoV, and the strength and toughness are slightly improved. The service life of D2 steel mold has different degrees of service life. High-speed steel (mainly W6Mo5Cr4V2 and W18Cr4V) has higher wear resistance and strength, and is often used to make molds, but its toughness cannot meet the needs of complex large and impact-intensive molds. In order to improve the toughness of this kind of steel, some new cold-working die steels have been developed in China, such as: 1 Low-alloy cold-worked die steel The main features of such steels are good manufacturability, low quenching temperature, small heat treatment deformation, and toughness. Good and have proper wear resistance. Such as GD (6CrMnNiMoVSi), 7CrSiMnMoV (referred to as CH), DS steel and the like. GD steel has a high service life for making cold-punching molds that are easy to chip and break. The composition of CH steel is the same as that of Japan's SX105V steel. It is a kind of flame-hardened steel. It is often used to make mold parts for automobile and other production lines. When flame quenching, it heats the cutting surface of the mold edge and has a high toughness under the hardened layer. The base is padded to give the mold a higher service life. DS steel is a kind of impact cold work die steel, and its impact toughness is significantly better than the commonly used high toughness blade tool steel 6CrW2Si. Gobo Moving Head Light,Led Beam Moving Head,Moving Head Spotlight,Mini Led Moving Head Light Big Dipper Laser Science And Technology Co., Ltd , https://www.bigdipper-laser.com