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Underwater in situ local heat treatment by additional stitches for improving the weldability of steel
Abstract
In this paper the influence of in situ local heat treatment performed by additional stitches on the weldability of high-strength low-alloy (HSLA) S355J2C+N steel was tested. The investigated steel is characterized by high susceptibility to cold cracking. It is necessary to find a method to improve the quality of welded joints. The local heat treatment was applied as an eect of bead-on plate welding made on the face of a Tekken test joint. The specimens were made by the use of covered electrodes in the water environment. For testing weldability, Tekken test specimens were made. Then, the dierent number of the pad welds with dierent overlapping were laid on the face of the tested welds. Non-destructive (NDT) visual and penetrant tests were undertaken. During the NDT, imperfections like shape mistakes and spatters were found. Then, metallographic macro- and microscopic testing were performed. The macroscopic observations proved that water environment can generate imperfections like cracking and pores. However, for specimens with additional stitches the number of imperfections decreased. Microscopic tests proved that the proposed technique aected the structure of the heat-aected zone (HAZ). The specimens without the application of additional stitches are characterized by brittle bainitic and martensitic structure. Specimens, in which the additional stitches were applied, contain tempered martensite, fine ferrite and fine pearlite in their HAZ. It was also observed that the number of cracks decreased for in situ local heat-treatment specimens. The final step was Vickers HV10 hardness measurement. These measurements confirmed previous results. The heat from additional stitches aected the steel by significantly decreasing the hardness by 80–100 HV10. The results of experiments showed that the heat from pad welds provided microstructural changes in heat-aected zones and a decrease in the susceptibility to cold cracking, which results in improvement in the weldability of HSLA steel in wet welding conditions.
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- Category:
- Articles
- Type:
- artykuły w czasopismach
- Published in:
-
Applied Sciences-Basel
no. 10,
pages 1 - 16,
ISSN: 2076-3417 - Language:
- English
- Publication year:
- 2020
- Bibliographic description:
- Tomków J., Janeczek A.: Underwater in situ local heat treatment by additional stitches for improving the weldability of steel// Applied Sciences-Basel -Vol. 10,iss. 5 (2020), s.1-16
- DOI:
- Digital Object Identifier (open in new tab) 10.3390/app10051823
- Sources of funding:
-
- Statutory activity/subsidy
- Verified by:
- Gdańsk University of Technology
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