Solutions to heat treatment deformation of seamless pipes

Solutions to heat treatment deformation of seamless pipes

Seamless steel pipe heat treatment refers to a seamless steel pipe thermal processing process that changes the chemical composition and structure of the surface or interior of seamless steel pipes through heating, insulation, cooling and other means to obtain the required performance.

The reasons for the deformation of seamless steel pipes are often complicated, but they can be reduced and controlled as long as the deformation rules are mastered, the causes are analyzed, and different methods are used to prevent the deformation of seamless steel pipes. Generally speaking, the following methods can be used to prevent heat treatment deformation of seamless steel pipes.

(1) Reasonable selection of materials. For seamless steel pipes, micro-deformation mold steel (such as air-hardened steel) with good material should be used. Mold steel with severe carbide segregation should be reasonably forged and tempered. For larger, non-forgeable mold steels, solution double refinement heat treatment can be performed.

(2) The structural design of seamless steel pipes should be reasonable, the wall thickness should not be too different, and the shape should be symmetrical. For molds with large deformation, the deformation rules should be mastered and machining allowance should be reserved. For large, precise and complex molds, a combined structure can be used.

(3) Seamless steel pipes should be preheated to eliminate residual stress generated during mechanical processing.

(4) Reasonably select the heating temperature and control the heating speed. For seamless steel pipes, balanced heating methods such as slow heating and preheating can be used to reduce heat treatment deformation of seamless steel pipes.

(5) On the premise of ensuring the hardness of seamless steel pipes, pre-cooling, graded cooling quenching or warm quenching processes should be used as much as possible.

(6) For seamless steel pipes, vacuum heating quenching and cryogenic treatment after quenching should be used as much as possible when possible.

(7) For some sophisticated and complex molds, preheating treatment, aging heat treatment, and quenching and tempering nitriding heat treatment can be used to control the accuracy of seamless steel pipes.

(8) When repairing defects such as trachoma, pores, and wear of seamless steel pipes, repair equipment with small thermal impact such as cold welding machines should be used to avoid deformation during the repair process.

In addition, correct heat treatment process operations (such as hole plugging, hole binding, mechanical fixing, appropriate heating methods, correct selection of the cooling direction of seamless steel pipes and the direction of movement in the cooling medium, etc.) and reasonable tempering heat treatment processes are also important in reducing unnecessary waste. Effective measures to prevent deformation of seamed steel pipes.

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