A weakly deoxidized Q420MPa grade marine climate
corrosion resistant steel, its composition and wt% are as follows: C: 0.05-0.15%, Si: 0.10-0.30%, Mn: 1.00-1.70%, P: 0.050-0.100%, S≤0.002%, Cu: 0.15-0.35%, Ni: 0.10-0.30%, Nb: 0.020-0.050%, Ti: 0.005-0.020%, O: 0. 0.010~0.025%, 0.020%≤Ce+La≤0.050%, 10%≤Si / O≤20%, 5%≤Mn / Si≤10%, CEV≤0.45, CEV=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15; Production process: After desulfurization of molten iron, it is smelted in a conventional converter; after
casting, the billet is heated; high-pressure water descaling; rough rolling; finish rolling; cooling to coiling temperature; coiling; and conventional subsequent processes. This invention achieves a stable ferrite +
pearlite +
bainite microstructure by ensuring a yield strength ≥410MPa, tensile strength ≥550MPa, and elongation after fracture ≥27%, using a low C, high P, and high O composition, adding certain amounts of Mn, Cu, Ni, Nb, Ti, Ce, La, etc., and achieving a low-temperature
impact energy of -60℃ ≥170J and an annual
corrosion rate of ≤1.3mm / y in marine climates.