Thermal processing of steel

Steel processing is divided into hot processing, cold processing and heat treatment 3 kinds. The billet is heated to a plastic state, and its shape is changed by external force to produce steel plates and sections of various thicknesses, which is called hot processing.

When the ingot or billet is heated to a certain temperature, the structure of the steel will be completely transformed into austenite state, austenite is the gap formed by the carbon dissolved into the iron (Y-Fe) of the face-centered cubic lattice, although the carbon content is high, its strength is low, plasticity is good, and it is easy to plastic deformation. Therefore, hot processing such as rolling or forging of steel is often selected in the appropriate temperature range when austenite is formed. The selection principle is that the temperature at the beginning of hot processing should not be too high, so as to avoid serious oxidation of the steel, and the temperature at the end of hot processing should not be too low, so as to avoid poor steel plasticity and cause cracks. General rolling and forging temperature control in 1150-1300 degrees Celsius.

The rolling of steel is through a series of rolls, the billet is gradually rolled into the required thickness of steel plate or section steel. Figure 2.1 is the rolling diagram of the wide flange H-section steel. Steel forging is the method of hammering or molding the heated billet into the desired shape of the workpiece, and some of the connected parts in the steel structure are often manufactured by this method.