A preparation device and method for a steel pipe with alternating strength and weakness

Abstract

The invention belongs to the field of hydroforming, and particularly relates to a preparation device and method of strong-weak alternatively distributed steel pipes. The preparation method comprises an upper mold, a lower mold, jacking blocks, a pressing head, hydraulic pumps, hydraulic pipes and fixing block bodies; a plurality of small pressing heads are arranged on the pressing head, and a plurality of grooves are formed in the inner peripheral surfaces of the upper mold and the lower mold at uniform intervals; a hydraulic hole is formed corresponding to the position of each groove of the upper mold, and the small pressing heads are arranged in the corresponding hydraulic holes correspondingly; first cavities are formed in the steel pipes blocked by the jacking blocks, second cavities are formed by the pipe walls of the steel pipes and the surfaces of annular grooves, and hydraulic oil is injected into the second cavities; and the hydraulic pumps and the hydraulic pipes provide bulging pressure for the first cavities, the pressing heads provide anti-bulging pressure for the second cavities. According to the preparation device and method of the strong-weak alternatively distributed steel pipes, repeated bulging-anti-bulging are carried out on parts of the steel pipes, strain is generated to induce martensite transformation, the content of martensite of the bulging-anti-bulging parts is increased, strong-weak alternatively distributed laminar structures are presented in the axial direction of the steel pipes, and the strong-weak alternatively distributed steel pipes are prepared.

Description

technical field [0001] The invention belongs to the field of hydroforming, in particular to a preparation device and method for a steel pipe with alternating strength and weakness. Background technique [0002] Stainless steel materials contain a variety of organizational structures, such as face-centered cubic austenite and body-centered cubic martensite. A large number of literatures show that the martensitic transformation has a great influence on the mechanical properties of stainless steel materials. Transformation Induced Plasticity (TRIP) refers to the strain-induced martensitic transformation of materials when subjected to external force or thermal load. The hard martensitic phase produced by the phase transformation and the mechanical incompatibility between the soft and hard phases can provide a high rate of strain hardening. Therefore, by plastically deforming austenitic stainless steel and introducing strain-induced martensitic transformation, the strain harden...

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Problems solved by technology

[0003] The stainless steel pipes manufactured by the traditional process have single structural properties and cannot meet the requirements of some special properties. For example, at the corners of the pipes, it is necessary to ensure that the pipes have good plasticity to facilitate the forming of the bends, and that the pipes have sufficient strength. , to withstand the impact of the liquid inside the pipe, the traditional pipe is a homogeneous material, which cannot meet the needs of good plasticity and high strength at the same time

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