Steel plate resistant to zinc-induced crack and manufacturing method therefor

Abstract

The invention discloses a steel plate resistant to zinc-induced crack and a manufacturing method therefor. A low-alloy steel subjected to low C-ultra low Si-high Mn-low Al—(Ti+Nb) microalloying treatment is taken as a basis; the Al content in the steel is appropriately reduced; the conditions are controlled so that Mn/C≥15, [(% Mn)+0.75(% Mo)]×(% C)≤0.16, Nb/Ti≥1.8 and Ti/N is between 1.50 and 3.40, CEZ≤0.44% and the B content is ≤2 ppm, Ni/Cu≥1.50; a Ca treatment is performed and the Ca/S ratio is controlled between 1.0 and 3.0, with (% Ca)×(% S)≤1.0×10; and a TMCP process is optimized, so that a finished steel plate has a micro-structure of ferrite+bainite colonies which are tiny and dispersedly distributed, with an average grain size of not greater than 10 μm, has homogeneous and excellent mechanical properties, excellent weldability and zinc-induced crack resistance, and is thus especially suitable as a zinc-spray coated corrosion-resistant steel plate for marine structures, a zinc-spray corrosion-resistant steel plate for extra-high voltage power transmission structures, a zinc-spray coated corrosion-resistant steel plate for coast bridge structures, and the like.