Heat Treatment of Steel Bar for Reinforced Concrete (GB 13014-1991)
The heat treatment of steel reinforcement for reinforced concrete structures is mainly to control the hardness and strength of steel, reduce the overall weight, and improve the formability, weldability and workability of steel. GB 13014-1991 Heat Treatment of Steel Bar for Reinforced Concrete specifies the requirements, test methods and inspection rules for the heat treatment of steel bars for reinforced concrete in China.
The heat treatment of reinforced steel is mainly carried out by quenching and tempering. The heat treatment process is mainly composed of heating, cooling, tempering and other processes. Quenching and tempering is to heat the steel bar to Austenitizing temperature and then quench the steel bar to below Ac3. After tempering tempering process, the structure of the steel bar will be changed, the brittleness will be reduced and the steel performance will be improved.
When selecting the quenching and tempering parameters, the requirements of GB 13014-1991 Heat Treatment of Steel Bar for Reinforced Concrete must be followed. The steel bar should be heated to a temperature of 750-850℃ for one hour, then quenched in water with a temperature of 10-18℃, and then tempered at 250-300℃ for two hours. The quenching temperature should not be too high or too low, otherwise the strength of the steel bar will be difficult to control, and the uniformity of the steel bar strength will be reduced.
GB 13014-1991 Heat treatment of steel bars for reinforced concrete also stipulates the requirements for the inspection of the heat treatment of steel bar for reinforced concrete. Among them, the cooling rate must not be greater than 6℃/s and the hardness of the steel bar after tempering should meet the requirements of the standard. Sampling is usually conducted on the basis of test batches (the inspection time and sample size should refer to the provisions of tables 2 and 3 of the standard).
The heat treatment of steel bars for reinforced concrete must be carried out in accordance with the requirements of GB 13014-1991, so as to ensure the uniformity of the steel bar strength and the quality of the entire reinforced concrete structure. The heat treatment of steel bars must be carried out by a qualified personnel and in accordance with the standard requirements to ensure that the heat treatment of steel bars meets the required performance requirements.
