EFFECT OF DIFFERENT COILING TEMPERATURES ON THE TISSUE PROPERTIES OF Q550D
The effect of coiling temperature on the microstructure of Q550D hot rolling was analyzed by comparing the microstructure properties of 6.0 mm Q550D hot rolling produced under different coiling temperature parameters.The results show that under the same chemical composition,heating system and laminar cooling mode,the structure of ferrite+pearlite can be obtained at a higher coiling temperature of 620 ℃,the average particle size is 4.98 μm,the grain size is 12,the tensile strength of the steel is 683 MPa,the impact energy is 62.7 J,all of which are the lowest values,but the elongation is 24％,and the plasticity is the highest.With the decrease of coiling temperature,small dispersed bainite begins to appear in the structure,which makes the steel have better tensile strength and low temperature impact toughness,but the plasticity decreases.When the coil-up temperature is reduced to 300 ℃,the structure is ferrite,bainite and a small amount of M/A island,the average particle size is about 5.58 μm,the grain size is 12,the tensile strength of the steel is 731 MPa,the impact work is 106.4 J,the plasticity is significantly reduced,and the elongation after breaking is lower than the lower limit of the national standard.In the actual production process of Q550D,the precipitation of pearlite or bainite structure should be controlled under the premise of maintaining a high grain size of the steel plate to meet the requirements of the comprehensive performance of Q550D,and too low coaling temperature is not conducive to the control of the comprehensive performance of the steel plate.
coiling temperatureQ550DBainitelaminar coolingimpact work
万方数据
维普
