Q690D grade is a low-alloy high-strength structural steel, belonging to the structural steel category. Q690D steel plate executive standard: GB/T16270-2009. Q is the expression of yield strength, 690 is its lower limit yield value, and D is its grade. This grade also has a higher yield strength and tensile strength. Q690 series grades also include Q690C, Q690D, Q690E, Q690F. Delivery status of steel S275ML steel plate: It should be delivered in quenched and tempered state. In addition, this grade can be delivered according to some special requirements of customers, but it should be indicated in the contract.
The toughness of steel such as S275ML steel plate is the ability of steel to absorb energy in the process of plastic deformation and fracture, and also the ability of steel to resist impact load. It is related to and different from the plasticity of steel. It is the comprehensive performance of strength and plasticity. The strength plasticity index of steel is obtained by static tensile test. When these indexes are used to bear the dynamic load structure, there are obvious limitations.
The main applications of normalizing are as follows:① For low carbon steel, S275ML steel plate. The hardness of low carbon steel after normalizing is slightly higher than that after annealing, and the toughness is also better, so normalizing can be used as the pretreatment of cutting.② For medium carbon steel, normalizing can be used as the final heat treatment instead of quenching and tempering treatment, or as the preparation treatment before surface quenching by induction heating.③ Normalizing can be used in tool steel, bearing steel, carburizing steel and so on, which can eliminate or inhibit the formation of network carbide, thus obtaining the good microstructure needed for spheroidizing annealing.④ Normalizing can refine the cast structure and improve the machinability of steel castings.
According to a report by yonhap news agency on April 26, under the impact of COVID - 19 epidemic, the steel industry chain was also affected. Hyundai lost 29.7 billion won. According to the report, the automobile and other downstream steel industry production stoppage directly led to a precipita-like decline in steel demand, is the main reason for the decline in steel enterprise performance of the main reason for hyundai said, hyundai kia motor production extension, by the end of April is expected to reduce production of 500,000 vehicles, as a result, S275ML steel plate, automotive steel demand will be reduced by 300,000 tons.