A cold-rolled martensitic steel with weather resistance and its manufacturing method

Abstract

The invention provides a weatherproof cold-rolled martensite steel and a manufacturing method thereof. The weatherproof cold-rolled martensite steel is manufactured from the following chemical components in percentage by weight (wt.%): 0.10%-0.20% of C, 0.20%-0.80% of Si, 1.4%-2.2% of Mn, 0.30%-0.80% of Cr, 0.08%-0.20% of Ni, 0.20%-0.50% of Cu, 0.08%-0.15% of V, 0.01%-0.30% of Ti, 0.0005%-0.003% of B, 0.015%-0.045% of Al, less than or equal to 0.020% of P, less than or equal to 0.007% of S, less than or equal to 0.008% of N and the balance of Fe and inevitable impurities. The manufacturing method comprises smelting, continuous casting, reheating, hot rolling, cold rolling, annealing and leveling, wherein for annealing, a continuous annealing mode of air cooling plus overaging is adopted to manufacture the weatherproof cold-rolled martensite steel of 1.0mm-1.4mm, and therefore, a steel plate manufactured is enabled to have the yield strength of more than 1000MPa, the tensile strength of more than 1100MPa and the elongation percentage A50mm% of more than 5%; no continuous annealing equipment having water quenching capacity is required; and the weatherproof cold-rolled martensite steel is suitable for parts such as containers and car door bumper bars having low forming requirements.

Description

technical field [0001] The invention belongs to the technical field of high-strength cold-rolled steel plate production, in particular to cold-rolled martensitic steel with weather resistance and a manufacturing method thereof. Background technique [0002] With the increasing energy crisis and environmental problems, both energy saving and safety have become the main considerations of container, automobile and other industries. The demand for steel for containers and steel for automobiles tends to be high-strength, lightweight and thin. In the field of high-strength steel with a tensile strength greater than 780MPa, phase transformation strengthening is the first choice for strengthening. Using phase transformation strengthening, a series of high-strength steel products such as dual-phase steel, multi-phase steel and martensitic steel can be produced. Tensitic steel has the highest strength, and the yield strength can reach more than 1200MPa. [0003] At present, cold-rol...

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Problems solved by technology

Although the composition is lower than that of the present invention, it adopts the water quenching + tempering route, which requires high equipment and does not have weather resistance

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