9SICR materials and characteristics.
9sicr steel is an alloy tool steel that has excellent hardenability and hardenability. Due to the silicon (Si) and chromium (Cr) content contained in the material, the material exhibits extremely high tempering stability and suitability for staged quenching. Although slightly less hardenable than CRWMN steel, it outperforms many common steel grades such as GCR15 in terms of performance.
Among the alloying elements, silicon (Si) plays a crucial role: it strengthens the steel and also raises the critical point temperature of the material. This keeps the amount of austenite remaining after quenching to a minimum, which in turn enhances the stability of the tempering. In addition, silicon refines the carbide distribution, which helps to improve wear resistance and plastic deformation resistance. Notably, 9siCR steel is effective at eliminating reticulated carbides and keeping the carbides fine and evenly distributed in the matrix.
The chemical composition of 9SICR complies with GB T 1299-2000 standard, and the content of the components is as follows:
Carbon (c): 085-0.95%
Silicon (Si): 120-1.60%
Manganese (mn): 030-0.60%
Chromium (cr): 095-1.25%
Phosphorus (p): 0030%
Sulfur (s): 0030%
9siCR Physical Properties.
Critical temperature (critical point temperature): AC1 770, AC3 870, AR1 temperature is 730.
9siCR forging process specification.
Ingot : heating temperature 1150 1200, first forging temperature 1100 1150, final forging temperature 880 800 cooling method. Slow cooling (sand cooling or pit cooling).
Billet: heating temperature 1100 1150, first forging temperature 1050 1100, final forging temperature 850 800 cooling mode. Slow cooling (sand cooling or pit cooling).
Preparatory heat treatment of 9siCR mold steel.
Annealing after forging: the heating temperature is 790 810, the heat preservation is 1 2h, and the furnace is cooled to below 550 and the furnace is air-cooled. The hardness after annealing is.
Isothermal annealing after forging:
The heating temperature is 790 810, the heat preservation is 1 2h, the isothermal temperature is 700 720, and the furnace is cooled to below 550 and the furnace is air-cooled. The advantage of isothermal annealing is that the transformation rate and uniformity of the austenite can be controlled for a more homogeneous structure and performance.
High temperature tempering: heating temperature is 600 700, heat preservation 2 4h, furnace cooling or air cooling, hardness is 197 241hbs. This step is used to eliminate cold deformation work hardening and restore plasticity and toughness to the steel.
Normalizing: heating temperature is 900 920, air cooling, hardness is 321 415hbs. The process is designed to refine the grains of the superheated steel and eliminate the reticulated carbides, providing a good microstructure basis for subsequent heat treatment.
Ultra-fine processing and final performance improvements:
By replacing the isothermal spheroidization annealing process with the ultra-fine treatment of forging waste heat quenching + high temperature tempering, uniform and fine punctate carbides can be obtained, which can basically eliminate carbide segregation and liquid precipitationFinally, after low-temperature quenching, the double-fine quenching structure can be finally obtained, which can greatly improve the performance of the mold. This treatment can make the mold have higher strength and wear resistance, while maintaining good toughness and processability.
Quenching and tempering of 9SICR.
Recommended quenching process specifications:
The quenching temperature is 860 880, the cooling medium oil, cooled to room temperature, the temperature is 62 65hrc. This temperature and cooling rate can ensure that the mold obtains sufficient hardness and wear resistance while maintaining good toughness.
Tempering: tempering temperature is 160 180, heat preservation for 2h, hardness is 61 63HRC. Tempering is the final link in the heat treatment of the mold, which can relieve stress, stabilize the size, improve toughness and achieve the best performance in use. At this tempering temperature, the mold can obtain the required tempering hardness and toughness to maintain its long-term stable performance.
Applications and precautions.
9SICR steel is often used to make cutting tools with complex shapes, low deformation requirements, and extremely high wear resistance. This material can also be used in the field of cold work molds, such as stamping dies, printing dies, etc. This is because it has very high hardness and strength, and it has excellent wear resistance and fatigue resistance. However, special attention needs to be paid to prevent oxidative decarburization when using it, so as not to affect its original hardness and corrosion resistance.