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Production method for improving comprehensive mechanical properties of T91 seamless steel tube

A seamless steel pipe, comprehensive mechanics technology, applied in the direction of metal material coating process, can solve the problems of long cycle, difficult to meet service conditions, and can not achieve energy saving and high efficiency, avoid oxidation and decarburization, omit annealing process, control The effect of furnace temperature stability

Active Publication Date: 2020-11-03
CHANGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The tensile strength of the finished pipe obtained through the traditional T91 production process is 680MPa-700MPa, the yield strength is 520MPa-540MPa, and the hardness is 200HBW-220HBW, which is still difficult to meet the service conditions of some specific environments, such as supercritical (SC) and ultra-supercritical (USC) unit pipes, etc., the service conditions are steam pressure ≥ 25MPa, steam temperature ≥ 580 ℃, tensile strength at room temperature ≥ 750MPa, yield strength ≥ 580MPa, hardness around 250HBW
At the same time, the traditional T91 production process has a long cycle, which cannot achieve energy-saving and high-efficiency effects

Method used

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  • Production method for improving comprehensive mechanical properties of T91 seamless steel tube
  • Production method for improving comprehensive mechanical properties of T91 seamless steel tube
  • Production method for improving comprehensive mechanical properties of T91 seamless steel tube

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] (1) Select the hot-rolled annealed T91 seamless pipe as the research object, and the steel pipe specification is Φ82mm×8.5mm;

[0039] (2) Carry out two passes of cold rolling to the steel pipe, carry out phosphating treatment in the middle of the two passes of rolling, and carry out degreasing treatment on the steel pipe after rolling, the cold rolling process is: the total deformation of cold rolling is 60%, the first pass The rolling deformation is 45%; the rolling deformation in the second pass is 26%, and no annealing is performed between the two passes;

[0040] (3) Quenching+tempering treatment is performed on the rolled steel pipe to obtain a finished pipe. Before quenching, preheat twice at 500°C, holding time for 10 minutes, and second preheating temperature at 800°C, holding time for 10 minutes. The quenching temperature is 1040°C, the holding time is 10min, and the cooling method is air cooling. The tempering temperature is 760°C, the holding time is 60min...

Embodiment 2

[0045] (1) Select a hot-rolled annealed T91 seamless pipe as the experimental object, and the steel pipe specification is Φ82mm×8.5mm;

[0046] (2) Cold rolling is carried out on the steel pipe, phosphating treatment is carried out in the middle of the two rolling passes, and oil removal treatment is carried out on the steel pipe after rolling. The cold rolling process is: the total deformation of cold rolling is 65%, and the rolling deformation in the first pass The rolling deformation in the second pass is 50%; the rolling deformation in the second pass is 24%, and no annealing is carried out between the two passes;

[0047] (4) Quenching+tempering treatment is performed on the rolled steel pipe to obtain a finished pipe. Preheat twice before quenching: the first preheating temperature is 500°C, the holding time is 10min, the second preheating temperature is 800°C, and the holding time is 10min. The quenching temperature is 1040°C, the holding time is 10min, and the cooling...

Embodiment 3

[0052] (1) Select a hot-rolled annealed T91 seamless pipe as the experimental object, and the steel pipe specification is Φ82mm×8.5mm;

[0053] (2) Cold rolling is carried out on the steel pipe, phosphating treatment is carried out in the middle of the two rolling passes, and oil removal treatment is carried out on the steel pipe after rolling. The cold rolling process is: the total deformation of cold rolling is 63%, and the rolling deformation in the first pass The rolling deformation in the second pass is 50%; the rolling deformation in the second pass is 22%, and no annealing is carried out between the two passes;

[0054] (4) Quenching+tempering treatment is performed on the rolled steel pipe to obtain a finished pipe. Preheat twice before quenching: the first preheating temperature is 500°C, the holding time is 10min, the second preheating temperature is 800°C, and the holding time is 10min. The quenching temperature is 1040°C, the holding time is 10min, and the cooling m...

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Abstract

The invention belongs to the technical field of metal material modification, and particularly relates to a method for improving the comprehensive mechanical properties of a T91 seamless steel tube. The method is characterized in that the first-pass rolling deformation is properly reduced, so that the hardness of the steel tube after first-pass rolling meets the requirements of second-pass rolling,and continuous two-pass cold rolling is realized, that is, common annealing treatment is not carried out between two passes of rolling, and only phosphating treatment is carried out; and then the rolled steel tube is subjected to quenching and tempering treatment with optimized process, so that the T91 finished tube with excellent comprehensive mechanical properties is obtained. According to themethod, the high-density dislocation obtained through first-pass rolling is reserved, the dislocation density is further improved and grains are refined through second-pass rolling, microstructures are further refined through quenching, alloy carbide / nitride distributed in a dispersed mode is formed in T91 steel through tempering, the strength and hardness of the seamless steel tube are further improved through dispersion strengthening, and meanwhile the plasticity is not obviously reduced.

Description

technical field [0001] The invention belongs to the technical field of metal material modification, and in particular relates to a production method for improving the comprehensive mechanical properties of T91 seamless pipes. Background technique [0002] T91 steel has high strength, good plasticity, good oxidation resistance and corrosion resistance, and can be used to manufacture high-pressure boiler reheaters, superheaters and other heating surface tubes with metal wall temperature < 625 °C and metal wall temperature ≤ 600 °C steam pipes etc. At this stage, T91 seamless steel pipes have gradually occupied the main position in the manufacture of large-capacity subcritical and supercritical power plant boilers in China. [0003] The tensile strength of the finished pipe obtained through the traditional T91 production process is 680MPa-700MPa, the yield strength is 520MPa-540MPa, and the hardness is 200HBW-220HBW, which is still difficult to meet the service conditions o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D8/10C21D1/18C23C22/73B21C37/06
CPCC21D8/105C21D1/18C23C22/73B21C37/06
Inventor 胡静周烨晖姚经松缪一新李和林
Owner CHANGZHOU UNIV