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Method for heat treatment of P92 steel

A heat treatment method and resistance heater technology, applied in heat treatment furnaces, heat treatment equipment, heat treatment process control, etc., can solve problems such as unsatisfactory, inability to effectively guarantee weld impact performance, and increased embrittlement tendency of P92 steel

Inactive Publication Date: 2010-06-09
天津诚信达金属检测技术有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] When P92 steel is operated for a long time in an ultra-supercritical unit with a parameter of 600 °C, the addition of tungsten promotes the precipitation of Laves phase and increases the embrittlement tendency of P92 steel. , must ensure sufficient impact energy, EN1597-1 standard stipulates the impact energy A for post-weld heat treatment of P92 weld deposit metal Kv ≥41J, the factors affecting the impact performance of P92 steel weld include welding process, post-weld heat treatment temperature and time, welding materials, etc., among which the post-weld heat treatment temperature and time have a crucial impact on the weld impact performance, and the process qualification test shows that When the temperature difference between the inner and outer walls of the P92 pipeline is greater than 30°C during the constant temperature process, the impact energy at the root of the weld is lower than 41J, which cannot meet the requirements of the EN1597-1 standard
[0004] At present, the post-weld heat treatment of pressure-bearing pipelines in thermal power plants is generally heated by flexible ceramic resistance heaters. The heating range is determined in accordance with the provisions of DLT / T819-2002 "Technical Regulations for Welding Heat Treatment in Thermal Power Plants". It can reach nearly 50°C. Although it can meet the requirements specified in the regulations that the temperature difference between any two points is less than 50°C within the heating range, it is qualified, but at this time the impact value of the root of the weld is lower than 41J, which cannot meet the EN1597-1 standard. Require
[0005] "Huaneng Power Plant P91, P92 Pipeline Site Post-weld Heat Treatment Process Guidelines (Trial)" provides the heat treatment process for P92 steel by flexible ceramic resistance heating. Can not effectively guarantee the impact performance of the weld

Method used

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  • Method for heat treatment of P92 steel
  • Method for heat treatment of P92 steel
  • Method for heat treatment of P92 steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] 1. Use the P92 main steam pipe of Φ538mm*91mm to weld according to the P92 steel welding process, and install a monitoring hot couple on the inner wall of the pipe before welding.

[0044] 2. Calculate the width of the heating zone HB=976mm, the width of the heat preservation zone GCB=1710mm, and customize the specifications of the heater and heat preservation cotton according to the calculated data.

[0045] 3. When the P92 pipe is welded and slowly cooled to 140°C, immediately press figure 1 The heater is installed as shown, the temperature control thermocouple is arranged in the center of the weld, and the temperature is controlled in three zones. When the temperature drops to 95°C, power on to keep the temperature at this temperature for 2 hours.

[0046] 4. Heating at 150°C / h to 300°C.

[0047] 5. After the temperature reaches 300°C, raise the temperature to 768°C at 80°C / h and keep it warm for 8 hours. At this time, the temperature difference between the monitor...

Embodiment 2

[0054] 1. Use the P92 main steam pipe of Φ433mm*72mm to weld according to the P92 steel welding process, and install a monitoring hot couple on the inner wall of the pipe before welding.

[0055] 2. Calculate the width of the heating zone HB=815mm, the width of the heat preservation zone 6CB=1370mm, and customize the specifications of the heater and heat preservation cotton according to the calculated data.

[0056] 3. When the P92 pipe is welded and slowly cooled to 140°C, immediately press figure 1 The heater is installed as shown, and the temperature control thermocouple is arranged in the center of the weld, and the temperature is controlled in two areas. When the temperature drops to 90 ° C, power on to keep the temperature at this temperature for 2 hours.

[0057] 4. Heating at 150°C / h to 300°C.

[0058] 5. After the temperature reaches 300°C, raise the temperature to 768°C at 80°C / h and keep it warm for 6 hours. At this time, the temperature difference between the moni...

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Abstract

The invention discloses a method for the heat treatment of P92 steel. In the method, a flexible ceramic resistor heating heat treatment process is adopted; and in the arrangement of a heating zone and a heat insulation layer, an internal and external wall temperature difference in a isothermal process is made less than 30 DEG C by reasonably determining the width of a heater and a heat insulation cotton and controlling temperature rise speed and heat insulation time so as to ensure the impact performance of weld joints and improve the service performance of the material.

Description

technical field [0001] The invention belongs to special steel heat treatment, in particular to a P92 steel heat treatment method. Background technique [0002] At present, with the development of the electric power industry and the increasing global concern for environmental issues, high-parameter, large-capacity supercritical (SC) and ultra-supercritical (USC) units have become an inevitable trend in the development of thermal power. Due to the P91 heat-resistant steel widely used in the pressure-bearing parts of boilers of thermal power generating units, its limit temperature is only 585°C, which cannot meet the needs of SC and USC units. P92 steel allows the main steam temperature of the boiler to be increased to 610°C, and the reheat temperature is as high as 625°C. It is more and more widely used in high-temperature headers and steam pipes of USC units. County Power Plant, Shanghai Waigaoqiao Power Plant and other units with a unit capacity of 1000MW and 600MW USC unit...

Claims

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Application Information

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IPC IPC(8): C21D9/08C21D11/00
Inventor 高洁安董艳柱田旭海柴丽文齐向前
Owner 天津诚信达金属检测技术有限公司
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