The role and precautions of stainless steel plate heating

The purpose of heating stainless steel plate is mainly to increase the plasticity of stainless steel, make the internal and external temperature of the billet tend to be uniform, and improve the metallographic structure of the material. In addition, the quality of the heating treatment will directly affect the output, quality and service life of the production equipment.

The heating furnaces used for heating medium and thick plates are divided into three types according to the structure: soaking furnaces, continuous heating furnaces and chamber heating furnaces.
Among them, the soaking furnace is mainly used in the occasion of rolling extra-thick stainless steel plates from steel ingots; the chamber furnace is suitable for occasions with many varieties and small batches, and the production form is highly flexible; the continuous heating furnace is suitable for the production of small varieties and large batches. However, in order to solve the problem of cold marks on the slideway, most of the continuous heating furnaces for medium and thick plates have been changed to hot slide rail type or walking type heating furnaces.
The heating temperature and heating time during heat treatment will affect the quality of the material. The temperature and the length of time in the furnace will directly affect the size of the original austenite grains. The longer the heating, the higher the temperature, and the larger the original grain size; and the heating temperature will directly affect the starting temperature, the higher the starting temperature, whether it is temperature-controlled rolling or reduction-controlled rolling control until the negative effects.
In addition to controlling the heating temperature, it is also necessary to control the heating rate. Due to the influence of metal thermal resistance, the surface temperature of the blank always rises faster than the central temperature during the heating process, which will form temperature stress inside, and the magnitude of this force is affected by the temperature gradient. The faster the heating rate and the greater the temperature gradient, the greater the thermal stress will be. When the thermal stress is greater than the rupture strength limit of stainless steel, cracks or fractures will occur inside the billet.
In addition, different stainless steel plate specifications also have different requirements for heating temperature. Usually, different heating temperatures are formulated according to the thickness of the board to be produced. Because the rolling passes of the thick gauge steel plate are less and the final rolling temperature is higher, the heating temperature of the thick gauge steel plate is about 20-30°C lower than that of the thin gauge steel plate. Because lowering the heating temperature can not only reduce the waiting time of the rolling process, but also refine the size of the initial austenite grain size and enhance the toughness and strength of the stainless steel plate.