Underwater In Situ Local Heat Treatment by Additional Stitches for Improving the Weldability of Steel
| Autor: | Anna Janeczek, Jacek Tomków |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Weldability 02 engineering and technology Welding cold cracking engineering.material lcsh:Technology 01 natural sciences law.invention lcsh:Chemistry Brittleness law Nondestructive testing 0103 physical sciences Water environment General Materials Science Composite material lcsh:QH301-705.5 Instrumentation 010302 applied physics Fluid Flow and Transfer Processes High-strength low-alloy steel bead-on plate welding lcsh:T business.industry Process Chemistry and Technology technology industry and agriculture General Engineering metallographic testing 021001 nanoscience & nanotechnology lcsh:QC1-999 Computer Science Applications underwater wet welding Cracking lcsh:Biology (General) lcsh:QD1-999 lcsh:TA1-2040 high-strength low-alloy steel engineering Pearlite lcsh:Engineering (General). Civil engineering (General) 0210 nano-technology business lcsh:Physics |
| Zdroj: | Applied Sciences Volume 10 Issue 5 Applied Sciences, Vol 10, Iss 5, p 1823 (2020) |
| ISSN: | 2076-3417 |
| Popis: | 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 effect 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 different number of the pad welds with different 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 affected the structure of the heat-affected 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 affected the steel by significantly decreasing the hardness by 80&ndash 100 HV10. The results of experiments showed that the heat from pad welds provided microstructural changes in heat-affected zones and a decrease in the susceptibility to cold cracking, which results in improvement in the weldability of HSLA steel in wet welding conditions. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|