Method for improving radial structure and performance uniformity of G115 steel large-caliber thick-wall pipe

Abstract

The invention discloses a method for improving radial structure and performance uniformity of a G115 steel large-caliber thick-wall pipe, and belongs to the technical field of steel materials. The process comprises the following steps of a normalizing system and a tempering system, wherein the normalizing system is characterized in that a tube blank subjected to hot-extrusion is adopted, chargingis carried out by using the temperature of 400-600 DEG C, warming is carried out with the heating speed of 100-120 DEG C / h until the temperature reaches 980-1000 DEG C, the hardening time is 0.5-1 min / mm, then warming is carried out with the heating speed of 130-150 DEG C until the temperature reaches 1030-1080 DEG C, then hardening is carried out, the hardening time is 0.5-0.8 min / mm, heat preservation is carried out for 1-3 hours after hardening, and air cooling or water quenching is carried out to the room temperature; and the tempering system is characterized in that charging is carried out by using the temperature less than or equal to 600 DEG C, warming is carried out with the heating speed of 120-150 DEG C / h until the tempering temperature reaches 780 + / - 10 DEG C, the time of heatpreservation is 3-5 hours, and air cooling is carried out to the room temperature. The method has the advantages that the radial temperature field of the thick-wall pipe is improved, moreover, the grain of the thick-wall pipe is not prone to coarsening, so that the radial structure and performance uniformity of the thick-wall pipe is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of iron and steel materials, and particularly relates to a method for improving the radial structure and performance uniformity of G115 steel large-diameter thick-walled pipes, which improves the radial structure uniformity of G115 steel large-diameter thick-walled pipes with a wall thickness of 60-150 mm, especially It is suitable for the manufacture of pipes related to super (super) critical thermal power units with steam parameters of 630-650 °C. Background technique [0002] Improving the steam parameters of thermal power units is the most important measure to improve the thermal efficiency of the unit and realize coal saving and emission reduction. [0003] Heat-resistant materials are the main "bottleneck" problem that restricts the development of thermal power units to higher parameters. Research and practice have shown that P92 martensitic heat-resistant steel can be used in the manufacture of some ...

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Problems solved by technology

[0012] The purpose of the present invention is to provide a method for improving the radial structure and performance uniformity of G115 steel large-diameter thick-walled pipes, and to solve the radial structure and performance of new martensitic heat-resistant steel G115 large-diameter thick-walled pipes with a wall thickness of 60-150 mm. The problem of unevenness, to overcome the shortcomings of the current technology

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