Optimizing method of 9% martensite steel pipeline postweld heat treatment heating width

Abstract

The invention relates to an optimizing method of 9% martensite steel pipeline postweld heat treatment heating width. According to the optimizing method, pipeline postweld heat treatment inner-outer wall temperature difference size data of T groups of pipelines with different sizes under different heating widths, different heat treatment environment temperature and different temperature control conditions are obtained through calculation. The minimum heating widths required by pipeline postweld heat treatment of the pipelines under different heat treatment environment temperatures, different temperature control temperatures and different preset inner-outer wall temperature differences are comprehensively considered, so that an error back propagation-based neural network is established for training and testing the minimum heating widths, pipeline size, heat treatment environment temperature, temperature control temperature and preset inner-outer wall temperature difference are used as inputs, and heating widths are used as outputs. By combining with actually measured data of the pipeline postweld heat treatment, a trained and tested network output threshold is corrected to obtain the optimizing method. According to the optimizing method, the minimum heating widths required by the postweld heat treatment can be rapidly calculated, a heat treatment process can be helped to be guided and optimized, and the heat treatment quality is improved.

Description

technical field [0001] The invention relates to a method for optimizing the heating width of a 9%Cr martensitic steel pipeline for post-weld heat treatment. Background technique [0002] 9%Cr new martensitic heat-resistant steel mainly includes three new martensitic heat-resistant steels: T / P92, T / P91 and E911, which are widely used in ultra-supercritical boiler main steam pipes, headers and other thick-walled pipes and other components , low weld toughness is a major problem in the installation process of this series of steel pipeline welds. In order to improve the toughness of the weld, local heat treatment must be carried out on the weld. Research at home and abroad shows that the post-weld heat treatment temperature has a great influence on the weld. Treatment, the impact energy of the weld can reach more than 41J. When heating at about 740°C, the constant temperature time must be extended to achieve this index. When the heating temperature is below 730°C, extending th...

AI Technical Summary

Problems solved by technology

Research at home and abroad shows that the post-weld heat treatment temperature has a great influence on the weld. Treatment, the impact energy of the weld can reach more than 41J. When heating at about 740°C, the constant temperature time must be extended to achieve this index. When the heating temperature is below 730°C, extending the constant temperature time not only has little effect, but the impact energy It is difficult to achieve the toughness index of 41J, and it will greatly increase the installation cost and seriously affect the construction progress

[0003] At present, on the basis of traditional heat-resistant steel, domestic and foreign have put forward the technical regulations for post-weld heat treatment of pressure-bearing pipelines. The post-weld heat treatment of Cr new martensitic heat-resistant steel is not necessarily applicable, that is, the applicability of existing standards to 9% Cr new martensitic heat-resistant steel needs to be verified

[0004] In addition, there are great disputes on the selection of heating width in domestic and foreign post-weld heat treatment specifications, and the heating width values ​​obtained according to different specifications are very different.

This brings difficulties to the on-site heat treatment, and the applicability of the regulations is questionable

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