World mold steel varieties of quality development direction will be around the high corrosion-resistant die steel, high molding die steel, high strength and high hardness die steel, heat-resistant oxidation-resistant die steel, high nitrogen die steel varieties of mold steel.

World mold steel varieties quality development will be around the following mold steel varieties:

High corrosion-resistant mold steel

The latest high corrosion-resistant die steel can be divided into two categories: a class called super die steel, Nippon Steel YUS270 (20Cr-18Ni-6Mo-N) its corrosion resistance equal to titanium.

YUS has a high chromium content, high molybdenum content, and can effectively use nitrogen to improve corrosion resistance. The coefficient of thermal expansion of YUS270 is between austenitic and ferritic die steel. It can be used in seawater purification devices, chemical plants, and buildings with severe corrosion of coastal sodium chloride. Ferritic mold steel SUS447J1 (30Cr-2Mo) is also a super mold steel.

Another type is HD ferritic mold steel.

By increasing the content of chromium and molybdenum and decreasing the content of carbon and nitrogen, corrosion resistance and formability can be improved. Typical HD ferritic die steels are Nippon Steel YUS220M (22Cr-1.5Mo-Ti-Nb), YUS190 and YUS190L (19Cr-2Mo), with slight variations in the chromium and molybdenum content of other die steels. 2Si-Mo-Cu), YUS110M (18Cr-12Ni-2Mo-Cu), and YUS27A-M (17Cr- 7Ni-2Cu-2Si) are the most recently developed high corrosion-resistant mold steels.

The composite addition of titanium and niobium prevents the precipitation of non-metallic inclusions as a source of corrosion and promotes the formation of oxide passivation films on titanium, thereby improving corrosion resistance. Nippon Steel has already adopted this technology there for YUS190 and YUS220M.

Composite additions of Ti, Nb and A1 have been reported to improve corrosion resistance. In addition, it was found that the traditionally considered harmful element S can improve the intergranular corrosion resistance of low chromium die steel, the same as nitrogen to improve the corrosion resistance of austenitic die steel. Future research to improve corrosion resistance will focus on the control of inclusions and surface protective coatings.

High molding die steel

Ferritic mold steel plasticity is poor. Although the austenitic mold steel high strength, but the coefficient of thermal expansion is high, not conducive to welding and other molding processes.

Under certain conditions, reducing the carbon and nitrogen content can significantly improve the formability and deep-drawing. For example, SUS430 r = 1.0, while the low carbon SUS430D r = 1. At the same time, the elongation can be stabilized at more than 30%. Continuous rolling YUS436Sr value significantly higher, especially after rolling large diameter roll SUS304 different, these new ferritic die steel in the appropriate stamping conditions can be ultra-deep stamping. Ultra-high cleanliness Fe-Cr alloy has a good into % of the die steel, the alloy has good formability, can obtain more than 36% elongation.

With the increase in die steel disc round production, processing methods from cutting to forging, developed a new die steel SUX7 with excellent cold forging performance. also developed additives S, Pb, Se easy to cut die steel and critical compression ratio improvement steel.

Recently, we are working on lubricatable die steel thin plates. The steel plate with organic coating on the surface can be formed without lubricant or protective layer, and has many uses in the requirements of improving the working environment and reducing production costs.Tokai Steel cooperated in the development of the name Guardooat die steel using organic coating.

High strength, high hardness mold steel

Development of SUS301L modified die steel for railroad carriages can be used as a high-strength, high-hardness structural material such as automotive gaskets and pressure plates. Martensitic mold steel with good corrosion resistance for public works and building components YUS550 (13Cr-2Ni-2Mo) can be used for cement punching without drilling. Adding nitrogen to SUS in 316 SUS316FR (16Cr-12Ni-2Mo-0.09N) can be used in fast breeder reactors where high temperature strength and creep strength are required. Ferritic mold steel with niobium addition YUS180H (19Cr-0.8Nb) and YUS340-MS (14Cr-0.5Mo-0.3Nb-Ti) can be used for high-temperature strength in automotive exhaust systems.

Heat and Oxidation Resistant Mold Steels

High chromium mold steels are heat and oxidation resistant. Addition of Al and Si can further improve the heat resistance and oxidation resistance of high chrome mold steel.YUS710(25Cr-13Ni-2Si-Mo- N) and YUS731(19Cr-13Ni-3Si-0.7Cu) au