High crack-arresting toughness steel plate with yield strength of 500MPa and production method thereof

Abstract

The invention provides a high crack-arresting toughness steel plate with yield strength of 500MPa and a production method thereof. The chemical components of steel comprises the following components in percentage by weight: 0.04-0.08% of C, 0.10-0.5% of Si, 0.8-1.6% of Mn, not more than 0.02% of P, not more than 0.01% of S, 0.03-0.065% of Al, not more than 0.005% of N, 0.005-0.05% of Nb, 0.005-0.03% of Ti, 0.0005-0.003% of B, not more than 0.004% of Ca, and the balance of Fe and avoidless impurities. The preparation method comprises the steps of roughing in an austenite re-crystalline region in a first stage, wherein the rolling temperature is 1000-1130 DEG C, the total reduction rate in the re-crystalline region is greater than or equal to 50%; cooling a rolled steel plate quickly to 580-530 DEG C at a rate of 10 DEG C / s; rolling in a non-re-crystalline region in a second stage when the temperature of the surface of the steel plate is 720-770 DEG C, wherein the accumulated deformation is greater than or equal to 50%, the finish rolling temperature is 700-740 DEG C; and water-cooling after rolling, wherein the cooling rate is 5-15 DEG C / s, and the final cooling temperature is 460-560 DEG C. The high crack-arresting toughness steel plate provided by the invention has the characteristics of high strength, high toughness, inhibition of crack formation and expansion and the like, and meets the performance requirements of special part members of large container ships.

Description

technical field

[0001] The invention relates to a steel plate with ultra-high strength and excellent low-temperature toughness produced by micro-alloy + controlled rolling and controlled cooling technology, especially its high crack arrest toughness can be used to manufacture steel for container hull structures in low-temperature environments. Background technique

[0002] With the enlargement of ships, the steel plates for shipbuilding are also developing in the direction of thicker plates. Especially for container ships, due to the requirements of the hull structure, thick plates with a thickness of 40-80 mm have been used as high-strength components in hatch coamings, upper decks and other parts. On the other hand, from the perspective of ensuring the safety of ships and preventing brittle fractures, ship steels are required to have a fracture toughness value above a certain level. In parts where cracks are expected to occur and in important parts where large-scale fract...

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