Local solution treatment method for stainless steel bent pipe

Abstract

The invention provides a local solution treatment method for a stainless steel bent pipe. The method comprises the following steps of: S1, placing the stainless steel bent pipe to be treated on a workbench, adjusting the position of a bending starting point of a bent part of the stainless steel bent pipe to be flush with the rotation center of the workbench, enabling the axis of a straight pipe part of the stainless steel bent pipe to be perpendicular to the rotation axis of the bending point, and then fixing the stainless steel bent pipe onto the workbench; S2, adjusting the position of the rotating center on the workbench till the position from the rotating center to the bending starting point of the bent part of the stainless steel bent pipe is the same as the bending radius of the bent part of the stainless steel bent pipe; and S3, controlling the workbench to drive a clamping assembly and the stainless steel bent pipe to rotate, and gradually heating and cooling the outer side of the bent part of the stainless steel bent pipe at the same time through using an induction heater. The flexibility and convenience of solution treatment are greatly improved, and the problems of cost control, deformation control, large-area oxide layer treatment and environmental protection caused by integral solution treatment are avoided.

Description

technical field [0001] The invention relates to the technical field of pipe fitting treatment, in particular to a local solution treatment method for stainless steel elbows. Background technique [0002] Small-diameter stainless steel elbows are widely used in industries such as ships, electric power, petrochemicals, and automobiles. They are used in large quantities and have complex application scenarios. Stainless steel elbows with a relatively small bending radius, especially cold-formed stainless steel elbows with a bending radius of less than 3D in the nuclear power industry, after bending, due to the large deformation rate, there will be obvious cold hardening phenomenon, and the toughness of the back of the elbow will decrease significantly. The minimum section elongation requirement specified in the material standard cannot be met. In order to solve the problem of toughness decline caused by cold bending, it is necessary to perform heat treatment on cold-bent pipes ...

AI Technical Summary

Problems solved by technology

[0005] (1) This solid solution treatment method is very easy to cause irregular deformation of long-dimensioned and complex-structured pipes, and the workload of correction after heat treatment is large: since stainless steel elbows usually have a certain length of straight section, and some elbows have complex structures, High precision is required. If the overall solution treatment is adopted, due to the uneven cooling of the water inlet and the release of the stress of the bend, it is easy to cause serious deformation of the bend. In this case, only mechanical methods can be used for correction, and the workload of correction is large. And it is easy to generate new stress;

[0006] (2) The cost of solid solution treatment is relatively high, even far exceeding the cost of bending pipes: the cost of starting a large heat treatment furnace is tens of thousands of yuan, but the cost of fuel consumption is sometimes greater than the cost of the bending pipe itself. If batch processing The quantity is small, unable to meet the standard of furnace opening, and can only wait for the furnace or start the furnace separately, which costs a lot and wastes resources;

[0007] (3) Measures such as sandblasting and pickling are required for the surface oxide layer after solution treatment, which are costly and difficult to clean: the temperature during solution treatment reaches above 1000°C, and a certain thickness of oxide layer will be formed on the surface after treatment, usually The surface cleaning method used is sandblasting or pickling. Since the elbow is heat-treated as a whole, oxidation occurs on both the inner and outer surfaces of the elbow. The cleaning cycle is long, difficult and costly;

[0008] (4) The purchase of solid solution treatment equipment needs to consider environmental protection factors: as various cities have higher and higher requirements for environmental protection and energy saving and emission reduction, they are becoming more and more cautious about the construction approval of large heat treatment furnaces, and some cities have even completely banned high energy consumption. Use of heat treatment equipment

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