Heat Treatment of Metals ›› 2024, Vol. 49 ›› Issue (6): 110-114.DOI: 10.13251/j.issn.0254-6051.2024.06.018

• PROCESS RESEARCH • Previous Articles     Next Articles

Effect of MA banded microstructure under different heat treatment states on HIC resistance of pipeline steel

Qu Zhiguo1,2, Zhang Youjian1,2, Wang Shiming1,2, Yu Hao1,2, Wang Dongming1,2   

  1. 1. Rizhao Steel Yingkou Medium Plate Co., Ltd., Yingkou Liaoning 115005, China;
    2. Liaoning Province Medium and Heavy Plate Professional Technology Innovation Center, Yingkou Liaoning 115005, China
  • Received:2023-12-06 Revised:2024-04-17 Online:2024-06-25 Published:2024-07-29

Abstract: Formation and elimination of MA microstructure in pipeline steel with 0.13%C under different rolling and heat treatment processes were studied, and the effect of MA banded microstructure on the hydrogen induced cracking (HIC) resistance of the steel was analyzed. The results show that the MA banded microstructure has a significant HIC resistance of the tested steel plate. By high-temperature tempering, the MA banded microstructure can be largely decomposed, and the HIC resistance is improved, especially with a significant reduction in crack thickness rate. After normalizing and fully austenitizing, the uneven distributed solute elements in the steel diffuse evenly, and the microstructure transforms into fine ferrite+pearlite structure after phase transformation. Although there is still fine pearlite bands, good HIC resistance can still be obtained. By normalizing and tempering treatment, MA bands caused by insufficient normalizing and austenitizing can be eliminated, and the fine pearlite bands exhibit intermittent distribution characteristic, thus the uniformity of the microstructure and HIC resistance can be further improved.

Key words: pipeline steel, MA microstructure, heat treatment process, hydrogen induced cracking

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