At present, foreign automobile manufacturers generally adopt isothermal annealing treatment for truck gear forging blank, and specify different isothermal annealing processes for different materials. For example, Volkswagen adopts isothermal annealing treatment of deformation waste heat, i.e. by treatment, and the forging blank of higher alloy truck gear is treated with by treatment and then high-temperature tempering BF treatment; Steyr company calls the isothermal annealing process BG treatment, which specifies the temperature and time of BG treatment of truck gear forging blank in detail, and the treatment quality is evaluated by hardness, metallographic structure and processing performance.
Foreign production practice shows that the truck gear treated by isothermal annealing not only greatly improves the machining performance, but also significantly reduces the deformation after carburizing and quenching. Therefore, the isothermal annealing process of truck gear forging blank is a new process that should be vigorously promoted.
With the development of China’s automobile production towards high quality and mass production, truck gear manufacturers pay more and more attention to the pre heat treatment of truck gear forgings. Modern mass production requires that the gear blank can obtain uniform structure and hardness after heat treatment to ensure good cutting performance and stable quenching deformation law. Therefore, the traditional pre heat treatment process (annealing and normalizing) can not meet the needs of modern production, and the isothermal annealing process is a more reasonable choice.
At present, the domestic equipment manufacturers represented by FAW Jiaxin company have provided dozens of isothermal annealing production lines for many domestic truck gear manufacturers, and have been actively applied to the production of various truck gears.