Submerged-arc welding process for 485 MPa-grade thick weather-proof bridge steel

Abstract

The invention discloses a submerged arc welding process for 485 MPa grade thick weather-proof bridge steel. The method belongs to the field of steel and iron material welding, and comprises the following specific steps: preparing a welding material matched with the 485MPa-grade thick weather-proof bridge steel; the groove type of the weather-proof bridge steel with the 485MPa-grade thickness specification is determined; and carrying out a submerged arc welding process on the 485MPa-grade thick weather-proof bridge steel. Welding materials and welding process parameters matched with high-performance bridge steel are adopted, the problem that low-temperature toughness, strength and cold bending performance of a thick-specification bridge steel welding joint are difficult to consider under the condition of large heat input is solved, and the high-standard requirement that the impact toughness of all parts of the joint at the temperature of-40 DEG C is higher than 60 J is met; the process of pre-welding low-temperature preheating and post-welding heat-free treatment is achieved, the effect of good welding joint performance and good welding seam forming is achieved in the implementation process, and the method is suitable for application and popularization of low-yield-ratio weather-proof series bridge steel for large-span structural engineering.

Description

technical field [0001] The invention belongs to the field of iron and steel material welding, and relates to a submerged arc welding process for weather-resistant bridge steel with a thickness of 485 MPa, in particular to a submerged arc welding process for a weather-resistant bridge steel with a yield strength of 485 MPa and a thickness and a low yield ratio. Background technique [0002] In the prior art, welding is the most important processing method for bridge steel to realize its application value, and the welding performance is also one of the most important usable properties of bridge steel; as the strength of steel increases, the welding quality requirements of steel also increase. , the quality of the joint directly affects the safety and reliability of the bridge. The strength and toughness of the joint is determined by various conditions such as the chemical composition of the base metal, the manufacturing process and the welding thermal cycle. Different welding ...

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Problems solved by technology

In the actual application of weather-resistant bridge steel, in order to improve the welding efficiency, the larger heat input energy is usually used for welding as much as possible. However, due to the high peak temperature during the welding thermal cycle, the weld metal is prone to produce coarse proeutectoid Ferrite, especially when the plate thickness is large, due to the long residence time at high temperature, coarser lath bainite and granular bainite are likely to be produced in the heat-affected zone of coarse grains, which will lead to embrittlement of the joint and difficult joint performance. ensure

At the same time, in practical engineering applications, most of the steel used for bridges is mainly in the QT state. However, this kind of steel plate not only has a long production cycle, complicated procedures, and high process costs, but also has relatively low yield strength due to the formation of tempered sorbite structure after quenching and tempering. High (>0.93), poor seismic performance, in order to reduce the yield ratio and improve the seismic performance of steel, the TMCP process is usually used in the bridge steel production process. The development direction of bridge steel in the new era, but due to the poor structure uniformity and large stress of TMCP steel compared with QT steel, it causes difficulties in the welding of bridge steel

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