Mechanical Properties and Notch Sensitivities of the Hydrogenated X70 Pipeline Steel Welded Joints

CHEN Ye, WANG Wanli, ZHAN Xianqiang, LIU Junjian, TANG Wenming

doi:10.16577/j.issn.1001-1560.2024.0197

Materials Protection >

2024 , Vol. 57 >Issue 9: 20 - 27

DOI: https://doi.org/10.16577/j.issn.1001-1560.2024.0197

Mechanical Properties and Notch Sensitivities of the Hydrogenated X70 Pipeline Steel Welded Joints

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(1.School of Materials Science and Engineering， Hefei University of Technology， Hefei 230009， China；2.Datang Boiler and Pressure Vessel Testing Center Co.， Ltd.， Hefei 230088， China；3.Datang East China Electric Power Test and Research Institute， Hefei 230088， China)

TANG Wenming(1969-)，Ph.D.，Professor，Research Focus:Material Failure and Reliability Assessment，Tel.:0551-62901362， E-mail: wmtang69＠126.com

Received date: 2024-07-05

Revised date: 2023-09-12

Accepted date: 2023-09-15

Online published: 2024-11-14

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Abstract

In order to explore the effects of pipeline inner-wall surface defects on reliability of the hydrogen enriched compressed natural gas(HCNG) pipeline steel welded joints in long-term service， the notches in the base metal， weld seam and heat affected zone of X70 pipeline steel welded joints were made，and the electrolytic hydrogen permeation on the notches was performed.Tests and analysis of the tensile mechanical properties， microstructures and notch sensitivities of the X70 pipeline steel welded joint notch samples with/without hydrogen permeation were carried out.Results showed that hydrogen permeation led to a decrease in the tensile mechanical properties of X70 pipeline steel welded joint samples， especially plasticity (elongation at break A).Due to the combined effect of notch and hydrogen damage， the tissue at the notch did not undergo significant deformation，and the tensile fracture exhibited quasi cleavage fracture characteristics.Furthermore，the welded joints of X70 pipeline steel with and without hydrogen permeation had certain notch sensitivity， and hydrogen permeation could increase the notch sensitivity of the welded joint.Therefore， the hydrogenated welding seams should be paid more attention during the pipeline maintenance， because of their higher notch sensitivity.

Key words： X70 pipeline steel; welded joint; electrolytic hydrogen permeation; notch sensitivity; hydrogen embrittlement sensitivity

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CHEN Ye, WANG Wanli, ZHAN Xianqiang, LIU Junjian, TANG Wenming . Mechanical Properties and Notch Sensitivities of the Hydrogenated X70 Pipeline Steel Welded Joints[J]. Materials Protection, 2024 , 57(9) : 20 -27 . DOI: 10.16577/j.issn.1001-1560.2024.0197

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