FH550 grade thick plate with excellent low temperature toughness and manufacturing method thereof

Abstract

The invention discloses a FH550-grade thick plate with excellent low-temperature toughness and a manufacturing method thereof. The steel contains 0.04% to 0.10% of C, 0.3% to 0.5% of Si, 1.0% to 1.6%of Mn, 0.5% to 0.7% of Cu, 0.5% to 0.7% of Ni, 0.2% to 0.4% of Cr, 0.2% to 0.3% of Mo, less than or equal to 0.01% of P, less than or equal to 0.01% of S, 0.01% to 0.05% of Als, 0.02% to 0.05% of Nb,less than or equal to 0.005% to 0.03% of Ti, 0.04% to 0.06% of V, less than or equal to 0.005% of N, and the balance of Fe and unavoidable impurities. The heating temperature of a casting blank is 1150-1200 DEG C; the first stage rolling temperature is 950-1000 DEG C, and intermittent water cooling is performed after rolling; the second stage rolling temperature is 840-890 DEG C; the third stage rolling temperature is 730-780 DEG C; the average cooling rate is greater than or equal to 3 DEG C / s, the open cooling temperature is 710-750 DEG C, and the red-returning temperature is 280-330 DEG C.The thickness of the produced steel for ship and ocean project is 50-80 mm, and the steel has excellent strength and low temperature toughness.

Description

technical field [0001] The invention belongs to the field of thick plate preparation, and in particular relates to a thick steel plate with high strength, thick gauge, and excellent low-temperature toughness, especially excellent low-temperature toughness in the 1 / 4 and 1 / 2 positions of the plate thickness direction, and a manufacturing method thereof. Background technique [0002] With the development of large-scale, light-weight and energy-saving ships and offshore platforms, the requirements for marine steel are getting higher and higher, and steel plates with high strength, excellent toughness, weldability and thick specifications are required. [0003] The classification societies of various countries have basically the same requirements for ship plate steel. The manufacturing process is generally produced by quenching and tempering process or TMCP process, but the quenching + tempering process has a long production process, complicated process, high cost and long delive...

AI Technical Summary

Problems solved by technology

The composition of the steel is designed as follows: C: 0.16%~0.18%, Si: 0.15%~0.35%, Mn: 1.10%~1.15%, P≤0.015%, S≤0.005%, Ni: 1.30%~1.40%, Cr: 1.20%~1.30%, Cu: 0.05%~0.10%, Mo: 0.45%~0.55%, Nb: 0.03%~0.04%, Ti: 0.020%~0.025%, V: 0.05%~0.06%, Al: 0.02% ~0.04%, B: 0.0014%~0.0023%; this technology adopts rolling + quenching and tempering heat treatment process, the manufacturing process is complicated, and the alloy cost and time cost are high

The average impact energy of this steel at -60°C is less than 100J, and there is no NDT test performance result, which cannot fully demonstrate the low temperature toughness performance

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