Welding method and welding joint for butt weld of cast steel pipe and hot rolled steel pipe

Abstract

The invention discloses a welding method and a welding joint for a butt weld of a cast steel pipe and a hot rolled steel pipe. The welding joint comprises a welding joint portion formed by weld ends of the hot rolled steel pipe and the cast steel pipe, the welding joint portion comprises two grooves and a base plate, the two grooves are formed in the weld ends of the hot rolled steel pipe and the cast steel pipe, the base plate extends from the weld end of the cast steel pope to the inner periphery of the hot rolled steel pipe, the distance from the top of the base plate to the outer periphery of the cast steel pipe is equal to the wall thickness of the hot rolled steel pipe, and the bottom of the base plate and the inner periphery of the cast steel pipe are in slope transition. The welding method includes the steps of integral casting of the steel pipes, machining of the grooves and the base plate, butt welding for connection and the like. The welding method and the welding joint have the advantages that welding difficulty can be lowered, stress concentration and residual stress generated in welding can be weakened, fatigue performance under reciprocate load effect is effectively improved, surplus height of the butt weld is reduced, and a welded product can acquire better appearance effects.

Description

technical field [0001] The invention relates to a welding form of cast steel pipes and hot-rolled steel pipes. More specifically, the invention is suitable for the welding of cast steel pipes with larger wall thicknesses and smaller wall thicknesses in the fields of long-span steel structures, bridges, and offshore platforms. Welded joints and their welding methods when connecting hot-rolled steel pipes with butt welds. Background technique [0002] In the current "Code for Design of Steel Structures" (GB50017-2003), only the allowable stress method is used to analyze the fatigue of the components, but there is no requirement for the fatigue of the welds of the components; while the "Technical Regulations for the Application of Cast Steel Pipes" In (CECS235:2008), although several application forms of cast steel pipes were proposed, the fatigue problems of cast steel pipes and their welding parts were not analyzed, calculated and explained; the most commonly used "Welding Ha...

AI Technical Summary

Problems solved by technology

[0003] Those skilled in the art know that for the welding connection of cast steel pipe and hot-rolled steel pipe, even if the outer diameter of cast steel pipe and hot-rolled steel pipe is the same, but because the wall thickness of cast steel pipe is greater than the wall thickness of hot-rolled steel pipe, so When the thickness difference between the two materials is large, it is easy to cause uneven geometry of the weld, and lead to obvious residual stress and welding defects in the finished product after welding, so that the residual tensile stress of the main metal near the weld often reaches the steel. Yield point, which is the most sensitive area for the formation and development of fatigue cracks

[0004] To sum up, the current engineering and the aforementioned various design specifications, technical regulations and welding manuals have not considered the fatigue problem of the welded joints of cast steel pipes. The key factor that the welded parts cannot meet the engineering technical requirements under the reciprocating load

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