Online repairing and annealing process for spheroidal graphite cast pipe

Abstract

The invention relates to an online repairing and annealing process for a spheroidal graphite cast pipe. The process comprises the following steps: surface polishing and / or machining is / are carried out on a defect or damaged part of the spheroidal graphite cast pipe to obtain a to-be-repaired part, synchronously feeding first powder into a laser cladding head, and at least one repairing layer is cladded on the to-be-repaired part of the spheroidal graphite cast pipe, then, laser energy generated when the second powder is synchronously fed into the laser cladding head is used for conducting laser stress relief annealing treatment on the repair layer of the cladding completed part, during laser stress relief annealing treatment, a powder feeding pipe of the second powder synchronously fed into the laser cladding head sprays a certain amount of Al powder to the laser stress relief annealing treatment part, the operations are alternately performed until the first powder is synchronously fed into the laser cladding head to complete cladding of the last repair layer, and the second powder is synchronously fed into the laser cladding head to complete laser stress relief annealing treatment on the last repair layer. The laser energy difference characteristic is fully utilized to introduce metal oxidation substance points for grain refining and strengthening, the process is controllable, and powder does not need to be mixed in advance.

Description

technical field [0001] The invention relates to the technical field of additive repair, in particular to an online repair and annealing process for ductile cast pipes. Background technique [0002] Ductile cast pipe, also known as ductile iron pipe, is a large-scale ductile iron pipe made by centrifugal casting process, some of which have complex shapes at the end of the pipe. The whole production process of ductile cast pipe is relatively complicated. Therefore, once surface or internal structure defects (such as cracks) are found during the casting and post-processing of ductile graphite pipes, or bumps occur during the casting and post-processing circulation, generally the first Consider repairing the damaged part, and consider scrapping the pipe only if it is determined that it cannot be repaired. [0003] At present, laser cladding is often used to repair ductile graphite pipes. When the damaged part is deep or the size is large, the damaged part will be milled out wit...

AI Technical Summary

Problems solved by technology

Laser cladding and additive repair operations have become increasingly mature, but they face two problems in terms of repair quality. One is that the tissue structure and mechanical properties of the repaired part are unstable, and the other is that the repaired part is subjected to repeated high-temperature shocks from high-energy processing beams. Inevitable processing internal stress, small and medium-sized parts can eliminate this internal stress by supplementing an annealing process, but for large ductile cast pipes, it is obviously not necessary to send the large ductile cast pipes back to the tube furnace for heat preservation and annealing Economical. For the former, those skilled in the art generally try to ensure the structural properties of the repaired part as much as possible by improving the composition of the repair material for welding, mainly by introducing a strengthening phase. For the latter, technicians have begun to try a high-energy beam online annealing process to eliminate Process internal stress to avoid heat treatment in the furnace. In additive repair, the energy of the welding laser is much higher than the energy of the annealing laser. Both welding and annealing are a short process. If the two connecting processes can be utilized, it is expected Eliminate some disadvantages in the formation and function of the strengthening phase, and reduce some unnecessary operations such as milling and mixing in industrial applications

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