Al-Qadisiyah Journal for Engineering Sciences

Non-destructive experimental test on the hardness and strength of steel exposed to temperatures of 250°C and 500°C

Articles in Press

Document Type : Research Paper

Authors

Zel Citra 1, 2
Antonius Antonius 1
Agung Wahyudi Biantoro 2
Han Ay Lie 3
Risma Apdeni 4

1 Doctoral Program in Civil Engineering, Faculty of Engineering, Universitas Islam Sultan Agung (UNISSULA), Semarang, Indonesia.

2 Department of Civil Engineering, Faculty of Engineering, Universitas Mercu Buana, Jakarta, Indonesia.

3 Department of Civil Engineering, Faculty of Engineering, Universitas Diponegoro, Semarang, Indonesia.

4 Department of Civil Engineering, Faculty of Engineering, Universitas Negeri Padang, Padang, Indonesia

https://doi.org/10.30772/qjes.2026.168669.1871
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
Subjects
Al-Qadisiyah Journal for Engineering Sciences

Articles in Press, Accepted Manuscript
Available Online from 10 May 2026

  • Receive Date 15 January 2026
  • Revise Date 28 March 2026
  • Accept Date 28 March 2026

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