Blind hole measurement method for value and distribution of residual stress of thick-wall and large-diameter welded steel pipe

Abstract

The invention relates to a blind hole measurement method for the value and distribution of residual stress of a thick-wall and large-diameter welded steel pipe. In the method, the cut length of a measured pipe body is no less than 2m; the same number of measuring points are distributed on the inner and outer surfaces of the measured pipe, and the distance between the measuring points on the same surface is no less than 40nm; the measuring points in a welded area are distributed in an area which covers half of the cut pipe segment and uses a welded joint cross point as the centre; measuring resistance strain gauges are X, Y and 45 degree three-way resistance strain rosettes; when the resistance strain rosettes are adhered, the X and Y directions are parallel and vertical to the welded joints of the measured pipe body, and the blind hole has a diameter Phi of 1.2 to 1.5mm and a depth of 2 to 2.5mm; and the size and direction of the residual stress value of each measuring point can be obtained by substituting the measured data together with the marked stress release coefficient in a blind hole stress measure equation. Thus, the blind hole measurement method can measure the value and the distribution of the residual stress of three types of thick-wall and large-diameter welded steel pipes including spiral pipes, UOE pipes and JCOE pipes.

Description

technical field [0001] The invention relates to a method for testing the residual stress value and distribution of thick-walled and large-diameter welded steel pipes by using a blind hole method. It is suitable for welded steel pipes with diameter ≥ 600mm, wall thickness ≥ 12mm, and forming welding methods: spiral submerged arc welding, UOE and JCOE. Background technique [0002] Residual stress usually refers to the stress that exists inside the component and remains in balance under the condition of no working load. Many steps in the welded pipe manufacturing process, such as pipe body forming and welding, will cause residual stress in the final welded pipe body. Residual stress will have an impact on the manufacturing quality and performance of welded pipes, and it is one of the main mechanical factors that cause stress corrosion of the pipe body and various welding cracks; in different degrees, especially under low temperature and dynamic load conditions, it reduces the...

AI Technical Summary

Problems solved by technology

The conventional blind hole method and measuring point layout cannot reflect this change

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