Weather resistant thick steel plate and manufacturing method thereof

Abstract

A weather resistant thick steel plate comprises, by weight, 0.06%-0.9% of C, not more than 0.30% of Si; 1.10%-1.50% of Mn, not more than 0.015% of P, not more than 0.003% of S, 0.035%-0.065% of Als, 0.25%-0.50% of Cu, 0.20%-0.50% of Ni, 0.40%-0.70% of Cr, 0.50%-0.15% of Mo, 0.008%-0.018% of Ti, 0.030%-0.060% of V, 0.015%-0.030% of Nb, not more than 0.0055% of N, 0.001%-0.004% of Ca, 0.0004%-0.0010% of selectively added B, and the balance of Fe and unavoidable impurities. The manufacturing method includes deep desulfurization of molten iron, converter smelting, LF, RH, continuous casting, on-line finishing of slabs, cut-to-length torch cutting of slabs, heating, TMCP, and slow cooling of steel plates. The obtained weather resistant thick steel plate has balanced strong toughness and strong plasticity, low yield ratio, atmospheric corrosion resistance, excellent weldability and fatigue resistance, and is especially applicable to non-coating high-rise building structures and bridge structures.

Description

technical field [0001] The invention relates to weather-resistant low-alloy steel, in particular to a low-alloy weather-resistant low-C-medium Mn-high Als-low N-(Cu+Ni+Cr) alloyed-(Nb+Ti+V) microalloy steel In the steel composition system, yield strength ≥ 490MPa, tensile strength ≥ 610MPa, yield strength ratio ≤ 0.83, Charpy transverse impact energy (single value) ≥ 47J at -40°C, and large heat input can be used to weld thick steel plates for weather-resistant structures (plate thickness ≥30mm), which is mainly used for high-rise building structures and non-painted large bridge structure manufacturing materials. Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridge structures, boiler pressure vessels, building structures, automobile industry, railway transportation and machinery under manufacture. ...

AI Technical Summary

Problems solved by technology

Since the Cr element greatly reduces the strength of steel plates with ferrite / pearlite microstructure and the reduction in yield strength is greater than the reduction in tensile strength, such as Xishan Memorial Technical Lecture 86-87, P11, so controlled rolling or normal Pyrotechnic production of yield strength ≥ 420MPa, tensile strength ≥ 550MPa, yield ratio ≤ 0.80, Charpy transverse impact energy (single value) ≥ 47J at -40°C, large input energy welding of thick steel plates for weather-resistant structures (thickness ≥ 40mm ), the carbon equivalent Ceq[C+Mn / 6+(Cr+Mo+V) / 5+(Cu+Ni) / 15] of the steel plate generally needs to be controlled above 0.46%, which will seriously deteriorate the low-temperature toughness of the base metal of the steel plate and weldability

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