What are the uses of SAE 4340 steel

     The SAE 4340 steel is a kind of special alloy steel, and it contains the main alloy elements are: molybdenum, nickel and chromium. Uses this steel manufacture the product to have the higher tensile strength, and the thermal stability and toughness are higher. That is why this steel is used to manufacture aircraft, automotive and other general engineering components. Molybdenum can reduce the temper brittleness.
     At present, the steel is also used in the manufacture of gear shaft, transmission shaft and car parts and gear lever. Tensile strength of the steel is higher than the 4140 steel, so can be get more strength. The last two digits of the carbon content of steel. This means that, when it is 4340 it contains carbon 40%, and when it is 4130 steel contains carbon 30%.

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How to heat treatment for H13 mould steel

     1. Preheat treatment. The market of H13 mould steel are after annealing heat treatment in steel mill, to ensure that it has a good metallurgical structure, appropriate hardness, good processability, don't need annealing once more. But after forging in the processing factory, the original microstructure and properties were destroyed, an increase of forging stress, must be re annealing.
Isothermal spheroidizing annealing process: 860 ~ 890 °C heating insulation 2h, cooled to 740 to 760 °C isothermal 4h, furnace cooling to 500 DEG baked.
     2. Quenching and tempering. The mould quenching process specification (requirements good toughness):the heating temperature is 1020 ~ 1050 °C, oil cooling or air cooling, hardness of 54 ~ 58HRC. If the requirements of the H13 steel good hot hardness, the quenching process specification is: the heating temperature is 1050 ~ 1080 °C, oil cooling, hardness of 56 ~ 58HRC. Recommendation tempering temperature: 530 ~ 560 °C, hardness of 48 ~ 52HRC; tempering temperature 560 ~ 580 °C, hardness of 47 ~ 49HRC. Tempering should be performed twice. Tempering at 500 °C, the peak of tempering hardening occurs, the tempering hardness is highest, hardness about 55HRC, but the toughness is worst. Therefore, the tempering process should avoid 500 °C advisable. According to the mold use need, tempering at 540 ~ 620 °C is  better. Quenching should be performed preheated twice (600 ~ 650 °C, 800 ~ 850 °C), to reduce the thermal stress in the heating process.
     3. Chemical heat treatment. H13 mould steel if the gas nitriding or nitrocarburizing can make the mould is further strengthened, but the nitriding temperature should not be higher than the tempering temperature, to ensure that the core strength is not reduced, thereby improving the service life of the mould.

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The performance of AISI D2 tool steel

     The wear resistance of AISI D2 tool steel is high, small deformation, the carbon content as high as 1.5%, chromium content up to 11.5%. After heat treatment, the hardness of D2 steel is up to 60HRC, but its ductility, toughness, resistance to rust ability are relatively weak, steel surface to mirror polished is not easy.
     Along with the cold stamping products to the development of high precision and high efficiency, multi species, requirement of die steel has good abrasion resistance and toughness. Compared with Cr12MoV steel, the D2 steel has increased by Mo and V in chemical composition, changing the cast structure of steel, improve the morphology of ledeburite, its strength and toughness and wear resistance is better than that of Cr12MoV steel, improve the service life of mould.
     The yield point and plastic deformation resistance of AISI D2 tool steel is higher than Cr12MoV steel, so the forging properties and thermal plastic forming is slightly worse than Cr12MoV. Cr12MolV, American D2, Japan SKD11, three although the same chemical composition, but the performance difference is very big. After heat treatment, Cr12MolV color slightly orange red, deformation is very large, prone to fatigue fracture at actual use; D2 steel is cold white color, hardness higher than SKD11, the toughness is lower than SKD11, high stress is easy to appear the tiny gap; SKD11 bright luster and the best overall performance.

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The advantages and disadvantages of DIN 1.2080 steel

    The 1.2080 steel is a kind of cold work die steel of high carbon and high chromium. The  content of C and Cr is very high, respectively C 2.00%~2.30% and Cr 11.00%~13.00% (mass fraction). DIN 1.2080 steel belongs to the ledeburite steel, so it has a very high hardenability, hardened and wear resistance, quenching deformation of small. But when the carbide heterogeneity, Its deformation are multi direction and irregular, its main drawback is poor organization. Uneven carbide is difficult to improve by heat treatment method, unless use powder metallurgy to manufacturing. Impact toughness is poor, thermal conductivity and high temperature plasticity is poor, when thermal processing should pay attention to heating and forging process.
    The 1.2080 steel is one of the international common cold work die steel, but in recent years has gradually been better steel replaced, such as Cr12MoV, Cr12Mo1V1 or matrix steel. The same type of foreign steel is 210Cr12 (ISO), Japan SKD1 (JIS), America D3 (AlSI/SAE) etc..
    1.2080 steel mainly for High wear resistance and impact load is smaller cold punching mould parts (the convex and concave mold, cold extrusion concave mold etc.), because of its obvious advantages and disadvantages, the use of limited.

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