Determination of forging temperature range for forgings

The forging temperature range of steel refers to the temperature interval between the beginning forging temperature (initial forging temperature) and the end forging temperature (final forging temperature). The forging temperature range of existing steel species HAS been determined through long-term production practice and safety analysis. It can be found out from the relevant HANDbooks. But with the continuous development of metal material science and technology, there will be more new steel to forge in the future. Therefore, it is not enough to choose the forging temperature range only, but also to grasp the scientific method of determining the forging temperature range. The basic principles of determining the forging temperature range are as follows: the steel is required to have good plasticity and low deformation resistance in the forging temperature chamber; Can forge high quality forgings; The forging temperature range should be as wide as possible in order to reduce the heating time and improve the forging productivity.

The basic method to determine the forging temperature range of forgings is to base on the balance diagram of steel, and then refer to the plasticity diagram, resistance diagram and recrystallization diagram of steel. The initial forging temperature and final forging temperature are determined by comprehensive analysis of plasticity, quality and deformation resistance. Generally speaking, the forging temperature range of carbon steel can be determined directly from the iron-carbon balance diagram. For most alloy structural steels, the forging temperature range can be considered as carbon steel with the same carbon content. However, for the high alloy indium with low plasticity and the steel without phase transformation, the reasonable forging temperature range must be determined through the test.

-- Determination of initial forging temperature

To determine the initial forging temperature of steel, it is necessary to ensure that the steel has no overburning phenomenon. In addition, factors such as blank structure, forging mode and deformation technology should be considered. For example, when ingot is used as billet, the tendency of overfiring is small because the as-cast structure is relatively stable, so the initial forging temperature of ingot is 20 ~ 50°C higher than that of billet and steel of the same type. When using high speed hammer precision forging, because high speed deformation produces great thermal effect, it will increase the temperature of blank and cause overburning, so the initial forging temperature should be about 10°C lower than the usual initial forging temperature. For large forgings forging, after a fire 朂 forging temperature, shall be determined according to the rest of the forging ratio, to avoid the coarse grains after forging, the heat treatment can't use steel of fine grains are important.

Second, the final forging temperature determination

When determining the final forging temperature, it is necessary to ensure that the steel has sufficient plasticity before the final forging, and to make the forgings have good structural properties. Therefore, the final forging temperature of steel should be higher than the recrystallization temperature to ensure that the recrystallization is complete after forging, so that the forgings get fine grain structure. The forging temperature range of various types of steels varies greatly. General carbon steel forging temperature range is relatively wide, up to 400 ~ 580°C. Molybdenum alloys, especially high-alloy steels, are narrow, ranging from 200 to 300°C. So in forging production, high alloy steel forging 朂 difficult, very strict with the forging process.