Method for improving radial structure uniformity of martensite heat-resistant steel large-caliber thick-wall pipe

Abstract

The invention discloses a method for improving radial structure uniformity of a martensite heat-resistant steel large-caliber thick-wall pipe, and belongs to the technical field of steel and iron materials. The method comprises the following steps that a pipe blank subjected to hot extrusion is adopted, is placed into a furnace, is heated to 930-980 DEG C by taking the heating speed of 100-120 DEGC per hour, then undergoes heat preservation for 1-6 hours, then is cooled to 740 DEG C + / - 10 DEG C, then undergoes heat preservation for 60-100 hours, and then is cooled along with the furnace; thepipe blank obtained through the above step is placed into the furnace, is heated to 980-1000 DEG C by taking the heating speed of 100-120 DEG C per hour, then is heated to 1040-1100 DEG C as soon aspossible, undergoes heat preservation for 1-3 hours after undergoing hardening, and then undergoes air cooling or water quenching to reach the room temperature; then the pipe blank obtained through the last step undergoes the tempering system, wherein the pipe blank is placed into the furnace is heated to the tempering temperature of 780 + / - 10 DEG C by taking the heating speed of 130-150 DEG C per hour, undergoes heat preservation for 3-5 hours, and then undergoes air cooling to reach the room temperature. The method has the advantages that the structure heredity is eliminated, the radial temperature field of the thick-wall pipe is improved, moreover, the grain is refined, and the uniformity of the radial structure and the performance of the thick-wall pipe is greatly improved.

Description

technical field

[0001] The invention belongs to the field of iron and steel materials, and relates to a method for improving the radial structure uniformity of a large-diameter thick-walled pipe of martensitic heat-resistant steel, which improves the radial direction of a large-diameter thick-walled pipe of a new type of martensitic heat-resistant steel with a wall thickness of 60-150 mm. Microstructure uniformity, especially 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] At present, several large power units in my country are actively preparing to build the world's first 630°C ultra-supercritical coal-fired demonstration power station; at the same time, entrusted by the National E...

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