With the development of science and technology and industry, the material put forward higher requirements, such as high strength, high temperature, high pressure, low temperature, corrosion, abrasion and other special physical and chemical performance requirements, steel can not fully Fulfil requirements.
Carbon steel major deficiencies in the performance of the following aspects:
(1) low hardenability. Under normal circumstances, the largest steel water quenching hardenability diameter of only 10mm-20mm.
(2) relatively low strength and yield strength. As Q235 common carbon steel σs is 235MPa, and low-alloy structural steel 16Mn of σs was 360MPa or more. 40 steel σs / σb is only 0.43, much lower than steel.
(3) tempering stability. Since tempering stability is poor, making quenched steel, high strength required in order to ensure a lower tempering temperature toughness of steel so it low; in order to ensure good toughness, high tempering temperature strength and low, so the level of mechanical properties of carbon steel is not high.
(4) can not meet specific performance requirements. Carbon steel in anti-oxidation, corrosion resistance, heat resistance, low temperature resistance, wear resistance and other aspects of special electromagnetic often poor, can not meet the needs of special use properties.