Comparing the performance of austempering with conventional quenching, the 60512Mn spring steel was used for comparative experiments. The ablation of the lower bainite structure obtained after austempering is much better than that of the conventional quenching tempering. The strength is increased by 34.5% and the yield strength is increased by 57.4%. The lower bainite spring has higher elasticity, toughness and plasticity under the premise of sufficient strength. When quenching, the structure is carried out in a constant temperature zone, and the cooling temperature difference is small, greatly The structure stress and thermal stress are reduced, the deformation and cracking tendency of the leaf spring during quenching are reduced, the hardness is relatively uniform after quenching, the soft point is not easy to occur, the salt liquid performance is stable, and aging is not easy to occur. The special process equipment for austempering in salt bath is austempering in a heated salt bath. The heat during quenching of the workpiece is absorbed by the salt bath. When the workpiece is cooled to the same temperature as the salt, it is air-cooled after a certain period of constant temperature. As the production volume increases, the temperature of the salt bath also rises due to too much heat released by the workpiece. If the salt temperature exceeds the process temperature, production should be stopped. When the salt temperature falls within the process temperature range, the production cannot be performed. Form mass production. In order to solve this problem, the traditional external heat or isothermal salt tank is first changed to the internal heat type. The heater is composed of several electric heating tubes and is divided into two parts, one part is movable type, and the other part is installed on the side and bottom of the salt tank. Fixed type, when heating is required, both the movable type and the fixed type heater are energized at the same time. When the salt bath temperature rises to the process temperature, the movable heater is taken out and the production can be performed. The fixed heater is powered by a thermocouple and a temperature measuring instrument to maintain a constant temperature by switching off and on. In order to improve the production efficiency, two isothermal salt tanks are manufactured. When the first salt tank is isothermal, it is removed from the quenching station, and the second salt tank is put into the quenching station to continue the work, so that the cycle works. In order to adapt to the influence of weather changes in the north on salt temperature, a dense and thick insulation layer is added to the bottom and sides of the salt tank to reduce heat loss and reduce energy consumption. Through the above measures, the lower bainitic steel body springs for automobiles and agricultural vehicles are transformed into actual productivity.