Process for bending X100 steel grade large-caliber bent pipe through intermediate frequency induction heating

Abstract

The invention discloses a process for bending an X100 steel grade large-caliber bent pipe through intermediate frequency induction heating, which comprises the following steps of: (1) selecting raw materials meeting the standard; (2) performing a thermal simulation experiment; (3) bending; (4) correcting to round the end of the bent pipe; (5) machining a groove; (6) performing thermal treatment, namely reasonably tempering, and eliminating the stress of the bent pipe by using a natural gas thermal treatment furnace; (7) performing surface treatment; and (8) detecting a finished product, wherein process parameters are that: the pushing temperature is between 960 and 990 DEG C, the pushing speed is 25mm / min, the cooling speed is 600 DEG C / min, the cooling water temperature is less than or equal to 40 DEG C, and the tempering temperature is between 500 and 530 DEG C. A straight pipe section and a bending section are wholly heated and tempered, so that the uniformity and consistency of the whole performance index of the bent pipe are ensured; the bent pipe does not have an obvious tissue transition region, so that the stress defect caused by different tissues is overcome; and the ovality of a bent part of the bent pipe is controlled by controlling the width of a heating strip, so that the product has a good appearance size.

Description

technical field [0001] The invention belongs to a method for processing bent pipes, in particular to a method for simmering X100 grade large-diameter bent pipes. technical background [0002] As the demand for clean energy such as natural gas continues to grow globally, natural gas pipelines have become globally interconnected, and the construction of gas transmission projects has also entered a peak period. In order to improve the transmission efficiency and reduce the cost of laying pipelines, high-grade X-series pipeline steel has become the main steel used, and gradually increasing the grade of steel has become the dominant idea. In the past ten years, the level of pipeline steel series steel pipes and pipe fittings has been gradually raised to X80 steel grade and widely used. Based on successful application examples and production experience, the initial trial production of X100 steel grade trunk pipes at home and abroad has been successful, but there is no successful ...

AI Technical Summary

Problems solved by technology

However, the manufacturing process of X100 steel-grade elbows is different from other lower-grade steel elbows. It has the following technical difficulties to overcome: First, the chemical composition of low-carbon micro-alloying, through quenching during simmering The strong and tough microstructure of X100 steel grade obtained by the process is relatively complex, and the process parameters of forming temperature and cooling rate are difficult to grasp

The second is that the large-diameter elbow itself is long, and there are several weak parts such as the heating transition zone and the weld seam. Any performance defect will affect the overall quality of the elbow

A small T / D ratio will increase the ellipticity of the bending section during simmering and reduce the quality of the appearance and size of the bend