Strength mismatching heat treatment process for petroleum steel tube in hardened and tempered state

Abstract

The invention discloses a strength mismatching heat treatment process for a petroleum steel tube in a hardened and tempered state, belonging to the technical field of metal engineering materials. The process comprises first-stage whole tube hardening and tempering and second-stage tube end hardening and tempering. According to the process, the strength mismatching of the tube body and the tube ends of the petroleum steel tube in a hardened and tempered state can be realized, the strength and toughness of the tube ends are higher than those of the tube body, and the strength and toughness of transition zones between the tube ends and the tube body are higher than those of the tube body but lower than those of the tube ends, thus ensuring that the steel tube has the performance distribution of strength mismatching accompanied with the distribution of toughness mismatching. The distribution of strength mismatching eliminates the weak point that the tube ends of the existing product are prone to deform or even break due to stress concentration caused by thread structures, and improves the service safety of the steel tube.

Description

technical field [0001] The invention relates to the technical field of metal engineering materials, in particular to a strength mismatch heat treatment process for quenched and tempered petroleum steel pipes. Background technique [0002] The steel pipes used in the petroleum industry mainly include drill pipes, oil pipes and casings. According to current industry standards, drill pipe and some small-diameter tubing and casing have pipe end thickening and heat treatment processes, so that they can be used to withstand misalignment of loads. As far as most oil pipes and casings are concerned, the pipe body and pipe end have a uniform outer diameter and wall thickness, and the end product becomes the end product after the pipe end is threaded and connected with a coupling. The final heat treatment of these oil pipes and casings is the overall conditioning treatment. After such treatment, the pipe body and pipe ends usually have the same strength. However, because the strength...

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Problems solved by technology

The final heat treatment of these oil pipes and casings is the overall conditioning treatment. After such treatment, the pipe body and pipe ends usually have the same strength. However, because the strength of the coupling is higher than that of the pipe body and pipe ends, plus Due to the stress concentration effect at the threaded connection part of the upper pipe end, the pipe end is prone to deformation, even fracture, tripping and other failures, resulting in economic losses in oil field production

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