Method for predicting weld seam impact energy of Austenitic heat-resistant steel after aging at temperature of 650 DEG C

Abstract

The invention discloses a method for predicting the weld seam impact energy of Austenitic heat-resistant steel after aging at the temperature of 650 DEG C. The method comprises the following steps of: measuring the relative precipitation quantity M of M23C6 in a practically running steel weld seam metal structure; and substituting M into a quantitative relation of AKV=10.71+34.96e<-M/0.87> to calculate AKV so as to predict the concrete numerical value and variation trend of the weld seam impact energy. Compared with the conventional impact energy test method, the decision method of the invention has the advantages of rapidly and quantitatively predicting an impact energy value after the running process of a Super304H steel weld seam metal, providing a basis for safety supervision of boiler components, avoiding damage to components and achieving convenience and rapidness.

Description

technical field [0001] The invention relates to a method for predicting the impact energy of a steel weld, in particular to a method for determining the impact energy of a new type of austenitic heat-resistant steel weld during the aging process, and belongs to the technical field of metal materials. Background technique [0002] Ultra-supercritical units are the main development direction of thermal power generation at present. With the improvement of steam parameters, the performance of steel materials is required to be continuously improved. For this reason, a number of new heat-resistant steels have emerged. The performance changes of these steels in the application process are still being explored. stage, and Super304H steel is one of the new austenitic heat-resistant steels, which is mainly used in the high-temperature section of the high-temperature superheater and reheater of ultra-supercritical boilers. Super304H steel has a certain aging embrittlement tendency in t...

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Problems solved by technology

The steam temperature of the superheater and reheater of the 1000MW ultra-supercritical boiler built in China is 605°C. In my country, the tube wall temperature is specified plus 50°C. Therefore, the metal operating temperature of Super304H steel parts is about 650°C, which is at the aging embrittlement temperature. range, while the boiler usually has certain requirements on the toughness of the material during the start-up and shutdown process. However, during the operation, the metal structure of the material will precipitate and grow, especially the M 23 C 6 The change of type carbide will have a great impact on the performance of the material, so it is necessary to understand the weak link in the welded joint after operation, that is, the embrittlement state of the weld metal, and to master the embrittlement state of the weld metal of Super304H steel after operation, It is usually necessary to continuously sample the pipes for impact energy testing, which not only increases the maintenance cost, but also increases the number of welded joints to cause performance degradation, and sometimes does not allow destructive tests on components. Therefore, at operating temperatures, it is necessary to propose a prediction Super304H steel Weld metal impact energy method, grasp the change of Super304H steel weld metal toughness after aging at 650°C, so as to realize effective supervision

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