Key Operating Points for O1 Steel Process and Maintenance
2026-06-10 11:301. Core Precautions for Heat Treatment
1.1 Annealing Stage
Control the temperature at 780-850℃, keep warm for 2-4 hours and slowly cool to below 500℃ before discharging from the furnace, ensure that the hardness of O1 steel after annealing is ≤235HB to meet the requirements of cutting processing. For stress relief annealing after rough machining, the temperature should be reduced to 650℃, kept warm for 2-4 hours, then slowly cooled and air cooled.
Soft annealing of O1 steel needs to be carried out in a protective atmosphere, and the cooling rate should be controlled to ≤15℃/h to avoid coarse grains that affect subsequent performance.
1.2 Quenching Stage
Preheating in sections is mandatory: first preheat to 600-700℃, then raise to the final quenching temperature of O1 steel 800-850℃, to reduce thermal stress and avoid cracking.
Oil quenching (80℃ warm oil is optimal) is preferred for cooling, and water quenching is prohibited for O1 steel. For workpieces with complex shapes, vacuum heat treatment or step quenching is recommended, which can effectively control the deformation. Temperature deviation will directly affect the performance of O1 steel: insufficient dissolution of carbides when the temperature is lower than 760℃ leads to insufficient hardness, while temperature higher than 840℃ will cause coarse grains and decreased toughness.
After quenching, the workpiece must be tempered immediately when cooled to 50-70℃, with an interval of no more than 2 hours, to prevent O1 steel from cracking during placement.
1.3 Tempering Stage
Select the tempering temperature according to performance requirements: choose low-temperature tempering at 180-200℃ to pursue high wear resistance of O1 steel, the hardness can reach 60-62HRC; choose medium-temperature tempering at 350-400℃ for better toughness, and the hardness is 57-60HRC.
Multiple tempering (≥2 times) must be guaranteed, each tempering lasts no less than 3 hours, to completely eliminate residual stress and prevent O1 steel from cracking in subsequent use. Double tempering (2 hours interval between two times) can be used for high-precision workpieces to further improve the stability of O1 steel.
1.4 Notes on Special Treatment
If you need to improve the hardness of O1 steel, you can immediately carry out cryogenic treatment at -70~-80℃ after quenching, keep warm for 3-4 hours and then temper, which can increase the hardness by 1-3HRC. However, cryogenic treatment is prohibited for O1 steel workpieces with complex shapes to avoid cracking risk.
2. Key Precautions in Use
Load Limitation: The toughness of O1 steel is lower than that of mold steels such as A2 and D2. O1 steel is prohibited from being used under overload in high-impact and high-stress scenarios, otherwise O1 steel is prone to cracking.
Environmental Adaptation: The chromium content of O1 steel is lower than 10.5%, so O1 steel is not stainless steel and has poor corrosion resistance: O1 steel is prohibited from being used in humid and corrosive environments for a long time; when it must be in contact with acidic media, additional surface antirust coating protection is required.
Welding Requirements: O1 steel has a high risk of welding cracking, so avoid welding repair unless necessary; when welding is mandatory for O1 steel, preheat the workpiece to 300-400℃ in advance, select welding rods with matching composition, and temper immediately after welding to eliminate brittleness.
Tool Selection for Processing: High-speed steel tools are recommended for processing annealed O1 steel, cemented carbide tools must be used for hardened areas, and cutting parameters should be optimized to reduce the heat-affected zone.
3. Precautions for Maintenance
Daily Rust Prevention: After use, dry the surface moisture and stains of O1 steel in time, and apply antirust oil regularly; store O1 steel for a long time need to do a good job of sealing and moisture protection, and increase the protection frequency in humid environments.
Regular Inspection: Regularly check the wear of O1 steel molds and tools, repair and replace them in time when there are tiny cracks or excessive wear, so as to avoid fracture caused by faulty operation.
Repair Specifications: Welding repair of O1 steel must strictly follow the preheating + tempering process, direct welding is prohibited to prevent embrittlement cracking in the heat-affected zone.