500MPa-class weather-resistant bridge steel with impact power being not lower than 54J in welded heat-affected zone at minus 40 DEG C

Abstract

The invention discloses a 500MPa-class weather-resistant bridge steel with impact power being not lower than 54J in a welded heat-affected zone at minus 40 DEG C. The weather-resistant bridge steel isprepared from the chemical components in percentage by weight: 0.04 to 0.08 percent of C, 0.20 to 0.40 percent of Si, 1.35 to 1.70 percent of Mn, 0.40 to 0.70 percent of Cr, 0.25 to 0.65 percent of Ni, 0.25 to 0.40 percent of Cu, 0.05 to 0.20 percent of Mo, 0.010 to 0.050 percent of Nb, 0.010 to 0.030 percent of V, 0.010 to 0.040 percent of Ti, 0.020 to 0.035 percent of Al, 0.0012 to 0.0050 percent of Ca, 0.0035 to 0.0080 percent of N, less than or equal to 0.0040 percent of O, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, and the balance Fe and inevitable impurities. According to the weather-resistant bridge steel provided by the invention, under the condition that the conventional electric-arc welding heat input ranges from 15 to 40Kj / cm, a structure of the welded heat-affected zone is formed by acicular ferrite, granular bainite and M-A components, so that the impact power of the welded heat-affected zone at minus 40 DEG C is not lower than 54J, the 500MPa-class weather-resistant bridge steel is weather-resistant and easy to weld, and the stable industrial production can be realized.

Description

technical field [0001] The invention belongs to the technical field of weather-resistant steel design and manufacture, and in particular relates to an easy-to-weld weather-resistant bridge steel with a yield strength of 500 MPa for large-scale paint-free bridges, and its welding heat-affected zone has excellent low-temperature impact toughness at -40°C. Background technique [0002] The Sichuan-Tibet railway and highway, a national key project under construction in my country, are located in harsh geological conditions such as alpine hypoxia, permafrost, landslides, scattered, landslides, earthquakes, geothermal heat, rock bursts, etc., but the climate conditions are relatively suitable, and many A super-long-span paint-free weather-resistant steel bridge must meet the design requirements of high load, fatigue resistance, brittle fracture resistance, safety, durability, and environmental protection. The existing 345-420MPa weather-resistant bridge steel has low strength, and ...

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Problems solved by technology

However, it will also increase the hard phase structure of the M-A component in the base metal and welding heat, resulting in poor low-temperature toughness of the steel plate (low-temperature impact energy at -40°C is only 150J), and insufficient low-temperature toughness in the welding heat-affected zone

[0012] It can be seen that the existing 500MPa weather-resistant bridge steel and similar materials have not studied the design and regulation of multi-element alloying components deeply enough, resulting in many deficiencies in the comprehensive performance regulation of high strength, weldability and weather resistance , it is urgent to carry out innovative design of materials to solve the major demand for key materials in the construction of Sichuan-Tibet Railway and Highway, a national key project

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