Analysis on Affecting Factors of Slab Surface Transversal Corner Crack for Medium-Carbon Steel with Boron in Continuous Casting

Based on the production practice of boron microalloyed medium-carbon steel, oscillating curve, cooling water flow in mould, secondary cooling system and arc alignment precision, rolling gap precision on transversal corner crack in slab was analyzed, and the corresponding control measures were put forward. Such as: Stabilizing the [S] and making w(S） less than 0.015%; Increasing Mn/S, and making the Mn/S was not less than 37.6 in A36-LB; Strictly controlling the w(Ca)/w(Als) was more than 0.09. Decreasing stroke 1mm and improving frequency to reduce negative sliding time 32%; Stabilizing cooling water around 4000/380 L/min, less cooling, reduce the total water cold water and 50% Side water; Testing rolling gap termly, strengthening maintenance and Replacing bad roller column to make sure precision in the reasonable scope, the measures above suppressed the corner crack in slab effectively, and it’s degradation ratio and quality disputes were below that of Q235B in the mouth production level.