Rail TIG welding method for black-and-white pipes

Abstract

The invention discloses a rail TIG welding method for black-and-white pipes, and belongs to the technical field of welding. When rail TIG welding is adopted for black-and-white pipe all-position welding, the difficulty lies in that smooth transition from welding materials in all directions (flat, downhill, uphill and the like) to a molten pool and stress balance in the molten pool crystallization process are guaranteed, otherwise, hot cracks are likely to appear on a base coat, inward concavities and the like are likely to appear on an overhead welding position, consequently, rail TIG welding cannot be successfully applied to butt joint of the black-and-white pipes, and wide application of rail TIG welding in boiler manufacturing is limited. According to the method, welding parameters are set in a partitioned manner, the welding rotating speed of the base coat is increased, the wire feeding amount and the welding current are reduced, and therefore the molten pool temperature at the overhead welding position at 4-7 o' clock is reduced, and generation of inward concavities of the base coat at the overhead welding position is effectively avoided; the welding rotating speed of a first filling layer at the overhead welding position is increased, the welding current is reduced, and the situation that when the first filling layer appears at the overhead welding position, inverse fusion is caused to the base coat, and consequently inward concavities are caused is effectively avoided; the welding parameters of the base coat are optimized, the arc extinguishing decay time and stroke are prolonged, the electric arc length is increased, and generation of arc extinguishing cracks of the base coat is effectively avoided; and the current and the wire feeding speed are changed in different areas, heat input of all the areas is accurately controlled, and generation of various poor fusion defects is effectively avoided.

Description

technical field [0001] The invention relates to an orbital TIG welding method for black and white pipes, belonging to the technical field of welding. Background technique [0002] With the development of new technologies and the increasing shortage of high-skilled welder resources in the market, in order to improve welding productivity and market competitiveness, boiler manufacturers are looking for intelligent solutions for welding automation. The application of orbital TIG welding in the butt joint of small pipes can improve welding production efficiency, reduce labor intensity of welders, and reduce the demand for all-position high-skilled welders in enterprises. However, orbital TIG welding in the market is only widely used in the butt joint of carbon steel materials, low alloy materials, and stainless steel materials. It has never been successfully applied to new heat-resistant steel materials T91 / T92 and austenitic stainless steel materials. (often referred to as "bla...

AI Technical Summary

Problems solved by technology

2) It is easy to appear concave in the upward welding position

In the upward welding position, the molten iron will flow downward due to the influence of gravity, resulting in concave

These two problems have not been solved for a long time, thus limiting the wide application of orbital TIG welding in the manufacture of boiler black and white tubes

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