ANALYSIS AND CONTROL OF SURFACE LONGITUDINAL CRACKS IN Q235B MEDIUM THICK PLATE
Q235B medium thick plate is one of the mainstream products of Jingye Group in 2022.However,since April,a large number of Q235B plates have shown longitudinal crack defects on the surface,accounting for 0.41％of the total production of Q235B,causing serious economic losses to the company.In response to the problem of a large number of plate degradation caused by surface longitudinal cracks in medium and thick plate Q235B,by tracking the steelmaking and continuous casting production process of Q235B slab,comparing the process parameters of longitudinal crack defects,the causes of longitudinal cracks were studied,and relevant control measures were formulated.Starting from three aspects:steel quality,pouring stability,and solidification balance of the billet,the occurrence rate of longitudinal cracks on the surface of Q235B slab is significantly controlled by controlling the carbon content of the steel smelting component to be 0.15％～0.17％,and the sulfur content to be less than 0.012％,ensuring the refining soft blowing effect,reducing inclusions in the steel,stabilizing the fluctuation of casting speed to be less than 0.1 m/min,optimizing the pouring process,controlling the depth of water inlet insertion to be controlled between 115～125 mm,optimizing the cooling system of the crystallizer,and balancing the heat flux density of the wide and narrow surface of the slab.In September,the proportion of longitudinal crack defects was 0.128％,a decrease of 0.283％compared to August.
medium thick plateQ235Blongitudinal fissurechemical compositioncontinuous casting operationcooling system
万方数据
维普
