Effect of forced weld cooling on high-strength low alloy steels to interpass temperature

Thesis event information

Date and time of the thesis defence

Place of the thesis defence

Linnanmaa Campus, L10. Remote connection: Zoom link: https://oulu.zoom.us/j/68589304056

Topic of the dissertation

Effect of forced weld cooling on high-strength low alloy steels to interpass temperature

Doctoral candidate

Master of Science (Technology) Juhani Markus Laitila

Faculty and unit

University of Oulu Graduate School, Faculty of Technology, Materials and Mechanical Engineering Unit

Subject of study

Production Engineering

Opponent

Professor Antti Salminen, University of Turku

Second opponent

Docent Mika Lohtander, Lappeenranta-Lahti University of Technology LUT

Custos

Professor Jari Larkiola, University of Oulu

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Effect of forced weld cooling on high-strength low alloy steels to interpass temperature

The aim of the thesis was to evaluate the effect of forced weld cooling on high-strength low alloy steels. The first objective of the study was to establish how does external cooling of the steel changes the mechanical properties of the welded joint. In addition to the overall effect of external cooling, the study focused on establishing the optimal temperature to which the steel should be cooled to. The second objective was to study how significant time savings could be achieved by introducing external cooling to the welding process.

It was found that when the welded joint was rapidly cooled to 100 degrees Celsius by introducing external cooling the mechanical properties of the joint either improved or remained unchanged. Furthermore, it was discovered that the enhanced cooling rate provided by the external cooling caused significant changes to the steel in the heat-affected zone that is produced by the welding process.

The external cooling studied reduced the weld cooling time by 30.8-83.6% depending on the heat input, plate thickness and work temperature.

Overall, the external cooling had no negative effects on the mechanical properties of the welded joint. Furthermore, it was found that by introducing a similar type of external cooling that was studied to welding processes, a significant amount of time could be shaved off the production time.
Last updated: 26.1.2021