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Non-destructive experimental test on the hardness and strength of steel exposed to temperatures of 250°C and 500°C | ||
| Al-Qadisiyah Journal for Engineering Sciences | ||
| Articles in Press, Accepted Manuscript, Available Online from 10 May 2026 PDF (6.86 M) | ||
| Document Type: Research Paper | ||
| DOI: 10.30772/qjes.2026.168669.1871 | ||
| Authors | ||
| Zel Citra* 1, 2; Antonius Antonius1; Agung Wahyudi Biantoro2; Han Ay Lie3; Risma Apdeni4 | ||
| 1Doctoral Program in Civil Engineering, Faculty of Engineering, Universitas Islam Sultan Agung (UNISSULA), Semarang, Indonesia. | ||
| 2Department of Civil Engineering, Faculty of Engineering, Universitas Mercu Buana, Jakarta, Indonesia. | ||
| 3Department of Civil Engineering, Faculty of Engineering, Universitas Diponegoro, Semarang, Indonesia. | ||
| 4Department of Civil Engineering, Faculty of Engineering, Universitas Negeri Padang, Padang, Indonesia | ||
| Abstract | ||
| This study evaluates changes in hardness and estimates the reduction in tensile strength of BJ37 structural steel after exposure to elevated temperatures of 250 °C and 500 °C using the Leeb hardness non-destructive testing (NDT) method. Since hardness is closely related to mechanical properties, the Leeb test can be used as an indirect approach to estimate tensile strength without damaging the material. A total of 36 specimens were prepared from the flange and web sections of a WF 300 X 150 X 6 X9 steel profile. The specimens were heated to 250 °C and 500 °C for 15 minutes and then rapidly cooled by water immersion before testing. The initial hardness was measured at approximately 366.19 HL, corresponding to an estimated tensile strength of about 372 MPa. After heating to 250 °C, the hardness decreased to 352.5 HL, with an estimated tensile strength of 342.5 MPa; at 500 °C, the hardness was 354.7 HL, corresponding to approximately 346 MPa. The reduction in tensile strength ranged from 7.0% to 7.9% relative to the initial condition, with only a small difference between the two temperature levels. These results indicate that the Leeb hardness method can serve as a rapid, non-destructive tool for the preliminary assessment of steel mechanical properties after fire exposure. Further research is recommended to validate these findings through destructive tensile testing, considering a wider range of temperatures, longer heating durations, and a larger number of specimens. The findings provide a practical basis for rapid post-fire evaluation of steel structural integrity. | ||
| Keywords | ||
| Steel Material; Non-Destructive Test; Hardness; Steel Strength Post-fire assessment | ||
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