The influence of temperature
1. Positive temperature influence: the overall influence law is that the temperature rises, the strength of the steel decreases, and the plasticity and toughness increase. When the temperature reaches about 450-600oc, the strength of the steel almost drops to zero, and the plasticity and toughness are extremely large, which makes it easy to heat for processing, this temperature is called the thermal calcining temperature.
2. The influence of negative temperature: as the temperature decreases, the strength of the steel increases, the plasticity and toughness decrease, and the brittleness increases. This is called low temperature cold brittleness. When the temperature drops to a certain temperature, the brittleness of the steel increases sharply. This temperature point is the turning brittle temperature.
The influence of production process
1. The smelting process mainly controls the chemical composition.
2. The influence of casting is mainly the deoxidizing method: Mn is used as deoxidizer for boiling steel, which is fast in time, low in price and poor in quality; Si is used as deoxidizer in killed steel, which is slow in time, high in price and good in quality.
3. Repeated rolling can make the steel size smaller, improve the plasticity of the steel, and weld the defects such as pores, cracks, and looseness in the steel, make the metal crystal structure compact, refine the crystal grain, and eliminate fiber structure defects , Improve the mechanical properties of steel. For steel of the same grade, the smaller the thickness or diameter, the higher the strength.
