Low-internal-stress steel for bridge structure and production method of low-internal-stress steel

Abstract

The invention discloses low-internal-stress steel for a bridge structure and a production method of the low-internal-stress steel. A steel plate comprises the following chemical components in percentage by weight: 0.10-0.15% of C, 0.25-0.50% of Si, 1.00-1.50% of Mn, less than than or equal to 0.002% of P, less than than or equal to 0.0010% of S, less than than or equal to 0.025% of Al, 0.010-0.070% of V, 0.040-0.060% of Nb, 0.01-0.05% of Ti, less than than or equal to 0.0065% and the balance of Fe and inevitable impurities, and meanwhile, V+Nb+Ti< / = 0.18, C+Si / 30+(Mn+Cu+Cr) / 20+Ni / 60+Mo / 15+V / 10+ 5B < / = 0.35, and C+Mn / 6+(Cr+Mo+V) / 5+(Cu+Ni) / 15 < / = 0.50. The steel plate is the low-internal-stress steel for the bridge structure, the yield strength is larger than or equal to 400 MPa, the tensile strength is 600-700 MPa, the ductility is larger than or equal to 25%, the structure is ferrite and pearlite, ferrite and pearlite are evenly distributed, the ferrite grain size reaches the 11-14 level, the internal stress of the steel plate is low after the steel plate is flattened, and the average stress of the steel plate is smaller than 40 MPa.

Description

technical field [0001] The invention relates to the field of steel manufacturing for bridge structures, in particular to steel for bridge structures with low internal stress and a production method thereof. Background technique [0002] With the development of bridges in the world and the progress of steel structure technology, more and more long-span bridges adopt steel structures, and orthotropic bridge decks are widely used in the construction of steel structure bridges due to their advantages such as light weight and strong bearing capacity. a wide range of applications. Orthotropic decks are mainly composed of steel structural panels and beams and longitudinal ribs welded to them. At present, most longitudinal ribs adopt U-shaped structure, and U ribs are an important part of bridge stiffeners. The bridge U-rib is mostly made of hot-rolled steel plate with a thickness specification of 6-12mm. At present, there are two supply methods. One is to use continuous hot roll...

AI Technical Summary

Problems solved by technology

However, this patent does not adopt the internal stress control method, so the steel plate has high residual stress, which will be deformed in the later use, affecting the user's use

[0004] The Chinese invention patent with the publication number CN105331880A discloses "a high-strength weather-resistant bridge steel and its preparation method". After smelting-continuous casting-rolling-stacking and slow cooling, it has high strength, excellent low-temperature toughness, low yield ratio, and welding It has the advantages of excellent performance and good weather resistance, but its chemical composition contains more alloys and the production cost is high

[0005] The Chinese patent with the publication number CN102021495A discloses "a preparation method of 420MPa high toughness weather-resistant bridge steel and its hot-rolled coil". After smelting-continuous casting-heating-2-stand rough rolling-7-stand finish rolling Laminar flow cooling—coils are used to obtain high-toughness weather-resistant bridge steel, but the chemical composition contains B elements, which are prone to crack defects

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