Detailed information

H13 mould steel belongs to electroslag remelting refining steel. The steel has high hardenability and resistance to thermal cracking and contains high content of vanadium. Its wear resistance is very good and has good heat resistance. At higher temperatures, it has good strength, hardness, wear resistance and toughness. Besides, H13 mould steel also has excellent comprehensive mechanical properties and high tempering stability and hardenability and resistance to thermal cracking. resistance to thermal cracking.

H13 mould steel is mainly used in the manufacture of impact load forging moulds, hot extrusion moulds, fine forging moulds, aluminum and copper and its alloy die casting moulds. It is a high quality steel based on the American H13 air hardening hot work mould steel. Its performance and use is similar to the 4Cr5MoSiV1 mould steel. Dessong H13 mould steel is customized from Fushun special steel. Its vanadium content is higher. In the medium temperature 600 degrees measured performance is slightly better than Fencol H13 mould steel. It is a reliable brand of hot work mould steel in recent years. The data has been verified for a long time in many demanding foreign enterprises.

The carbon content in the steel determines the matrix hardness of the quenched steel, as can be known by the comparison of the relationship curve between the carbon content in the steel and the hardness of the quenched steel. The quenching hardness of Desson H13 mould steel is around 55 HRC. For the mould, part of the carbon in the material enters the steel matrix causing solid solution strengthening. Another part of the carbon will be combined with the carbide forming elements in the alloying elements into – Taikin carbide. For hot work mould steel, this alloy carbide in addition to a small amount of residual, but also requires it in the tempering process in the quenched martensite matrix diffuse precipitation to produce two hardening phenomenon, so that the uniform distribution of residual Taikin carbon compounds and tempering martensite organization to determine the performance of hot work mould steel. Dessong H13 mould steel in the refining process after strict technical control and professional melting, ensure its excellent performance and purity.

Process Control Measures and Heat Treatment

From the chemical composition and organizational characteristics of H13 mould steel, it can be seen that the thermal processing process has a great impact on the organization and performance of H13 mould steel. In order to prevent early failure of H13 mould steel, extend the service life and improve economic efficiency, it is necessary to develop a scientific and reasonable thermal processing process.

Forging process

H13 mould steel has high alloying element content, poor thermal conductivity and relatively low eutectic temperature, which can easily cause overburning. Larger diameter billets should first in 800 ~ 900℃ zone preheating, and then in the beginning of the forging temperature 1065 ~ 1175℃ heating, forging for several times to draw long upsetting. The total forging ratio is greater than 4. Pre-heat treatment of market supply of H13 mould steel steel and mould billets, in the steel mills, it has been good annealing heat treatment, to ensure a good metallurgical organization, appropriate hardness, good workability. Without annealed, but the manufacturing plant to change the forging destroyed the original organization and performance, increased forging stress, must be re-annealed.

Spheroidizing and Annealing Process

The purpose of the spheroid annealing process is to homogenize the tissue, reduce the hardness, improve the cutting performance, and prepare the tissue for quenching and tempering. Spheroidized annealing process is in 845 ~ 900℃ insulation ( 1h + 1min ) / mm, then furnace cooling to 720 ~ 740℃ isothermal ( 2h + 1min ) / mm, and finally furnace cooling to 500℃ out of the furnace air cooling, spheroidized annealing organization for granular pearl, hardness less than 229HBS. Spheroidized quality can be assessed according to GB/T1299-2000 standard first level chart.

* Quenching and Tempering Process

The best heat treatment process of H13 mould steel is 1020 ~ 1080 ℃ heating and oil cooling quenching or graded quenching, then 560 ~ 600℃ two tempering, microstructure for tempering taustenite + tempering sothite + remaining carbide, microhardness of 48 ~ 52 HRC. For the requirements of high thermal hardness of mould casting mould can be quenched at the upper heating temperature. For the requirements of the toughness of the main mould (hot forging mould) can be quenched at the lower heating temperature.

Chemical Heat Treatment

H13 steel can be further strengthened by gas nitriding or nitrogen-carbon infiltration, but the nitriding temperature should not be higher than the tempering temperature to ensure that the strength of the heart is not reduced, thereby improving the service life of the mold.

Isothermal Spheroidizing Annealing

860 ~ 890℃ heating and holding 2h, cool down to 740 ~ 760℃ isothermal 4h, furnace cooling to about 500℃ out of the furnace.

Quenching Process for Good Toughness

Heating temperature 1020~ 1050℃, oil cooling or air cooling, hardness 54 ~ 58HRC

Quenching Process for Hot Hardness

Heating temperature 1050 ~ 1080℃, oil cooling, hardness 56 ~ 58HRC. Recommended tempering temperature 530 ~ 560℃, hardness 48 ~ 52HRC; tempering temperature 560 ~ 580°C; hardness 47 ~ 49HRC. Tempering should be carried out twice. At 500℃ tempering, there is a tempering secondary hardening peak with the highest tempering hardness, peaking at about 55 HRC, but the worst toughness. Therefore, the tempering process should be avoided around 500°C. According to the use of the mold needs, tempering in the range of 540 ~ 620℃ is better. Quenching heating should be preheated twice: 600 ~ 650℃ , 800 ~ 850℃ to reduce the heating process to produce thermal stress.

Delivered hardness of mould steel is: 235HB (customizable).