Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel Welds
High Strength Low Alloy (HSLA) steels are the materials of choice in pipeline construction with the API X70 grade as the steel for the majority of pipeline networks constructed during the late 20th and early this century. This paper reports on the influence of Post-Weld Heat Treatment (PWHT) on the...
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MDPI AG
2020-12-01
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| Series: | Materials |
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| Online Access: | https://www.mdpi.com/1996-1944/13/24/5801 |
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| author | Houman Alipooramirabad Anna Paradowska Shahrooz Nafisi Mark Reid Reza Ghomashchi |
| author_facet | Houman Alipooramirabad Anna Paradowska Shahrooz Nafisi Mark Reid Reza Ghomashchi |
| author_sort | Houman Alipooramirabad |
| collection | DOAJ |
| description | High Strength Low Alloy (HSLA) steels are the materials of choice in pipeline construction with the API X70 grade as the steel for the majority of pipeline networks constructed during the late 20th and early this century. This paper reports on the influence of Post-Weld Heat Treatment (PWHT) on the reduction of residual stresses, resulting changes in the microstructure, and mechanical properties of a multi-pass, X70 HSLA steel, weld joints made by a combined Modified Short Arc Welding (MSAW) and Flux Cored Arc Welding (FCAW) processes. Neutron diffraction results highlighted high magnitude of tensile residual stresses, in excess of yield strength of both parent and weld metal, in the as-welded specimen (<inline-formula><math display="inline"><semantics><mo>~</mo></semantics></math></inline-formula>650 MPa), which were decreased substantially as a result of applying PWHT (<inline-formula><math display="inline"><semantics><mo>~</mo></semantics></math></inline-formula>144 MPa). Detailed microstructural studies are reported to confirm the phase transformation during PWHT and its interrelationship with mechanical properties. Transmission Electron Microscopy (TEM) analysis showed polygonization and formation of sub-grains in the PWHT specimen which justifies the reduction of residual stress in the heat-treated weld joints. Furthermore, microstructural changes due to PWHT justify the improvement in ductility (increase in the elongations) with a slight reduction in yield and tensile strength for the PWHT weld joint. |
| first_indexed | 2024-03-10T13:56:13Z |
| format | Article |
| id | doaj.art-74a92f1acd174531820813d5b8bd271c |
| institution | Directory Open Access Journal |
| issn | 1996-1944 |
| language | English |
| last_indexed | 2024-03-10T13:56:13Z |
| publishDate | 2020-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Materials |
| spelling | doaj.art-74a92f1acd174531820813d5b8bd271c2023-11-21T01:35:07ZengMDPI AGMaterials1996-19442020-12-011324580110.3390/ma13245801Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel WeldsHouman Alipooramirabad0Anna Paradowska1Shahrooz Nafisi2Mark Reid3Reza Ghomashchi4School of Engineering, University of British Columbia, Okanangan, BC V1V 1V7, CanadaAustralian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, AustraliaSchool of Mechanical Engineering, the University of Adelaide, Adelaide, SA 5005, AustraliaAustralian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, AustraliaSchool of Mechanical Engineering, the University of Adelaide, Adelaide, SA 5005, AustraliaHigh Strength Low Alloy (HSLA) steels are the materials of choice in pipeline construction with the API X70 grade as the steel for the majority of pipeline networks constructed during the late 20th and early this century. This paper reports on the influence of Post-Weld Heat Treatment (PWHT) on the reduction of residual stresses, resulting changes in the microstructure, and mechanical properties of a multi-pass, X70 HSLA steel, weld joints made by a combined Modified Short Arc Welding (MSAW) and Flux Cored Arc Welding (FCAW) processes. Neutron diffraction results highlighted high magnitude of tensile residual stresses, in excess of yield strength of both parent and weld metal, in the as-welded specimen (<inline-formula><math display="inline"><semantics><mo>~</mo></semantics></math></inline-formula>650 MPa), which were decreased substantially as a result of applying PWHT (<inline-formula><math display="inline"><semantics><mo>~</mo></semantics></math></inline-formula>144 MPa). Detailed microstructural studies are reported to confirm the phase transformation during PWHT and its interrelationship with mechanical properties. Transmission Electron Microscopy (TEM) analysis showed polygonization and formation of sub-grains in the PWHT specimen which justifies the reduction of residual stress in the heat-treated weld joints. Furthermore, microstructural changes due to PWHT justify the improvement in ductility (increase in the elongations) with a slight reduction in yield and tensile strength for the PWHT weld joint.https://www.mdpi.com/1996-1944/13/24/5801PWHTneutron diffractionHSLAmicrostructural characterizationEBSD |
| spellingShingle | Houman Alipooramirabad Anna Paradowska Shahrooz Nafisi Mark Reid Reza Ghomashchi Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel Welds Materials PWHT neutron diffraction HSLA microstructural characterization EBSD |
| title | Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel Welds |
| title_full | Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel Welds |
| title_fullStr | Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel Welds |
| title_full_unstemmed | Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel Welds |
| title_short | Post-Weld Heat Treatment of API 5L X70 High Strength Low Alloy Steel Welds |
| title_sort | post weld heat treatment of api 5l x70 high strength low alloy steel welds |
| topic | PWHT neutron diffraction HSLA microstructural characterization EBSD |
| url | https://www.mdpi.com/1996-1944/13/24/5801 |
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