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Cracking Failure Analysis of X70 Pipeline Steel Weld

  • Bin Wang
  • Senfeng Zhang
  • Cui Zhou
  • Nan Liu
  • Liang Wang
  • Xiaoyu Tian
Conference paper
Part of the Springer Proceedings in Energy book series (SPE)

Abstract

The weld defects were detected by Nondestructive Testing Technology(NTT). The microstructure and microhardness were examined by optical microscope(OM), scanning electron microscopy (SEM) equipped with EDS and Vicker microhardness tester to identify the reasons of cracking failure in X70 pipeline steel weldment. As a result, the microstructure in the root layer and filling layer of the weld presents ferrite and pearlite while it is ferrite and bainite in the covering layer, but the morphology and distribution as well as the content of ferrite and pearlite in the root layer are different from which in the filling layer; the cracks initiate at the root of the weld and propagate towards filling layer, and the C, O, S segregation is serious, which contribute to the initiation and propagation of the crack in the weld; the hardness decreases sharply around the crack tip, which exhibits lower strength.

Keywords

Microstructure Cracks Segregation 

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Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  • Bin Wang
    • 1
    • 3
  • Senfeng Zhang
    • 1
  • Cui Zhou
    • 2
  • Nan Liu
    • 4
  • Liang Wang
    • 1
  • Xiaoyu Tian
    • 5
  1. 1.School of Materials Science and EngineeringSouthwest Petroleum UniversityChengduChina
  2. 2.Shanghai Jianke Engneering Consulting Co. LtdShanghaiChina
  3. 3.Sichuan Provincial Research Center of Welding Engineering TechnologyChengduChina
  4. 4.Sichuan Petroleum and Natural Gas Construction Engineering Co. LTDChengduChina
  5. 5.One Two Project Management Co. LTDChengduChina

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