Post-fire hardness and impact resistance tests of high-strength grade 8.8 steel bolts

• Autorzy: Król Paweł A.

Identyfikatory

DOI

10.24425/ace.2025.155119

Warianty tytułu

PL

Pomiary twardości i udarności śrub o podwyższonej wytrzymałości klasy 8.8, po symulowanej ekspozycji pożarowej

• Języki publikacji: EN

Abstrakty

EN

The article presents results of hardness and impact resistance tests of grade M20-8.8 bolts, previously subjected to simulated fire conditions. The tests were aimed at assessing the effect of temperature, fire exposure time, and cooling method on the hardness and impact resistance of bolts subjected to a fire in the context of fastener post-fire suitability for further use. Knowledge of these two parameters may be crucial from the point of view of expert assessment of the safety of structures that survived the fire. This may be of particular importance in the case of structures located in seismic and paraseismic areas, and subject to dynamic loads. Test specimens were received from bolts previously subjected to simulated thermal actions, which were supposed to reflect environmental conditions of a real fire. They were heated at temperatures of 100ºC, 150ºC, 200ºC, 300ºC, 400ºC, 500ºC, 600ºC, 700ºC, 800ºC, 900ºC, and 1000ºC for periods of 30′, 60′, 120′ and 240′, respectively, and then cooled at various rates, which resulted in the differentiation of the material microstructure. After heating, some of the bolts were cooled naturally, left to cool down freely at ambient temperature, whereas some other were rapidly cooled by immersion in water until they cooled completely, thus simulating the effect of an intensive firefighting operation. The obtained results were elaborated on to assess their usefulness in the analyzes of structures that survived the fire and, due to the nature and extent of damage, are the subject of considerations regarding the possibility of their further use.

PL

W artykule zaprezentowano wyniki pomiarów twardości oraz udarności śrub jakościowych M20-8.8, wykonanych ze stali stopowej 32CrB3, poddanych wcześniej symulowanym oddziaływaniom pożarowym. Celem badań była ocena wpływu temperatury, czasu ekspozycji pożarowej i metody chłodzenia na twardość i udarność śrub po ekspozycji pożarowej, w kontekście przydatności łączników do ich dalszego wykorzystania, po pożarze. Znajomość tych dwóch parametrów – poza wynikami uzyskiwanymi tradycyjnie z klasycznej statycznej próby rozciągania – może być istotna z punktu widzenia eksperckiej oceny bezpieczeństwa konstrukcji, które przetrwały pożar. W szczególności może mieć znaczenie w przypadku konstrukcji zlokalizowanych na terenach sejsmicznych i parasejsmicznych, oraz obciążonych w sposób dynamiczny. Próbki do badań pobrano ze śrub poddanych uprzednio symulowanym wpływom termicznym, mającym odzwierciedlać warunki środowiskowe realnego pożaru, wygrzewanych w temperaturze 100ºC, 150ºC, 200ºC, 300ºC, 400ºC, 500ºC, 600ºC, 700ºC, 800ºC, 900ºC i 1000ºC przez okres odpowiednio 30′, 60′, 120′ i 240′, a następnie studzonych ze zróżnicowaną prędkością, co finalnie spowodowało zróżnicowanie mikrostruktury materiału. Po wygrzaniu, część śrub chłodzono w sposób naturalny, pozwalając im ostygnąć swobodnie na powietrzu, drugą zaś część studzono w sposób gwałtowny, przez zanurzenie w wodzie aż do całkowitego wystudzenia, symulując tym samym efekt akcji ratunkowo-gaśniczej. W każdej z serii przebadano po 3 próbki, celem weryfikacji poprawności i powtarzalności uzyskanych wyników. Omówiono uzyskane wyniki oceniając ich przydatność w analizach konstrukcji, które przetrwały pożar i z uwagi na charakter oraz wielkość zniszczeń rozważa się możliwość ich dalszej eksploatacji.

• Wydawca: Komitet Inżynierii Lądowej i Wodnej PAN ; Politechnika Warszawska, Wydział Inżynierii Lądowej
• Czasopismo: Archives of Civil Engineering
• Rocznik: 2025
• Tom: Vol. 71, nr 3
• Strony: 571--586
• Opis fizyczny: Bibliogr. 42 poz., il., tab.

Twórcy

autor

Król Paweł A.

• Warsaw University of Technology, Faculty of Civil Engineering, Warsaw, Poland

• https://orcid.org/0000-0003-2586-5492

Bibliografia

• [1] M. Maślak, “Badania stali konstrukcyjnej po pożarze w kontekście oceny możliwości jej dalszego użytkowania w elementach nośnych ustrojów budowlanych (Testing of construction steel after a fire to assess the possibility of its continued use in the load-bearing elements of built structures)”, Przegląd Budowlany, no. 6, pp. 48-51, 2012.
• [2] M. Maślak and G. Żwirski, “Zmiany strukturalne w stali konstrukcyjnej wywołane epizodami jej nagrzewania i stygnięcia podczas pożaru (Changes in structural Steel Microstructures Following Heating and Cooling Episodes in Fires)”, Bezpieczeństwo i Technika Pożarnicza, vol. 48, no. 4, 2017, pp. 34-52, doi: 10.12845/bitp.48.4.2017.2.
• [3] T.G. Digges, S.J. Rosenberg, and G.W. Geil, Heat treatment and properties of iron and steel. National Bureau of Standards Monograph 88. Washington D.C., USA: United States Department of Commerce, 1966.
• [4] J.D. Verhoeven, Steel metallurgy for the non-metallurgist. Materials Park, Ohio, USA: ASM International, The Materials Information Society, 2007
• [5] P.A. Król and M. Wachowski, “Effect of Fire Temperature and Exposure Time on High-Strength Steel Bolts Microstructure and Residual Mechanical Properties”, Materials, vol. 14, no. 11, art. no. 3116, 2021, doi: 10.3390/ma14113116.
• [6] P.A. Król, “Post-fire behavior and residual capacity of high-strength grade 8.8 steel bolts”, Archives of Civil Engineering, vol. 70, no. 3, pp. 85-100, 2024, doi: 10.24425/ace.2024.150972.
• [7] T. Molkens, K.A. Cashell, and B. Rossi, “Post-fire mechanical properties of carbon steel and safety factors for the reinstatement of steel structures”, Engineering Structures, vol. 234, art. no. 111975, 2021, doi: 10.1016/j.engstruct.2021.111975.
• [8] P.A. Król, “Post-fire properties of bolt steel, quenched and tempered in the production process”, Archives of Civil Engineering, vol. 71, no. 2, pp. 429-450, 2025, doi: 10.24425/ace.2025.154130.
• [9] V. Kodur, M. Yahyai, A. Rezaeian, M. Eslami, and A. Poormohamadi, “Residual mechanical properties of high strength steel bolts subjected to heating-cooling cycle”, Journal of Constructional Steel Research (ASCE), vol. 131, pp. 122-131, 2017, doi: 10.1016/j.jcsr.2017.01.007.
• [10] A.S. Daryan and H. Ketabdari, “Mechanical properties of steel bolts with different diameters after exposure to high temperatures”, Journal of Materials in Civil Engineering (ASCE), vol. 31, no. 10, art. no. 04019221, 2019, doi: 10.1061/(ASCE)MT.1943-5533.0002865.
• [11] G.-B. Lou, S. Yu, R. Wang, and G.-Q. Li, “Experimental study on mechanical properties of high-strength bolts after fire”, Proceedings of the Institution of Civil Engineers. Structures and Buildings, vol. 165, no. 7, pp. 373-383, 2012, doi: 10.1680/stbu.11.00015.
• [12] C. Maraveas and Z. Fasoulakis, “Post-fire mechanical properties of structural steel”, presented at 8th National Steel Structures Conference, Tripoli, Greece, 2014.
• [13] C. Maraveas, Z. Fasoulakis, and K.D. Tsavdaridis, “Mechanical properties of High and Very High Strength Steel at elevated temperatures and after cooling down”, Fire Science Reviews, vol. 6, no. 3, 2017, doi: 10.1186/s40038-017-0017-6.
• [14] C. Maraveas, Z. Fasoulakis, and K.D. Tsavdaridis, “Post-Fire Assessment and Reinstatement of Steel Structures”, Journal of Structural Fire Engineering, vol. 8, no. 2, pp. 181-201, 2017, doi: 10.1108/JSFE-03-2017-0028.
• [15] X-Q. Wang, Z. Tao, and M.K. Hassan, “Post-fire behavior of high-strength quenched and tempered steel under various heating conditions”, Journal of Constructional Steel Research, vol. 164, art. no. 105785, 2020, doi: 10.1016/j.jcsr.2019.105785.
• [16] Z. Tao, X.Q.Wang, and B. Uy, “Stress-strain curves of structural and reinforcing steels after exposure to elevated temperatures”, Journal of Materials in Civil Engineering (ASCE), vol. 25, no. 9, pp. 1306-1316, 2013, doi: 10.1061/(ASCE)MT.1943-5533.0000676.
• [17] Z. Chen, J. Lu, H. Liu, and X. Liao, “Experimental study on the post-fire mechanical properties of high-strength steel tie rods”, Journal of Constructional Steel Research, vol. 121, pp. 311-329, 2016, doi: 10.1016/j.jcsr.2016.03.004.
• [18] P-C. Peng, J-H. Chi, and J-W. Cheng, “A study on behavior of steel structures subjected to fire using non-destructive testing”, Construction and Building Materials, vol. 128, pp. 170-175, 2016, doi: 10.1016/j.conbuildmat.2016.07.056.
• [19] PN-EN ISO 148-1:2017-02 Metale – Próba udarności sposobem Charpy’ego – Część 1: Metoda badania (Metallic materials – Charpy pendulum impact test – Part 1: Test method). Warszawa, PKN, 2017.
• [20] ASTM E0023-24 Standard test method for notched bar impact testing of metallic materials. West Conshohocken, PA, USA, ASTM International, 2024.
• [21] Y.J. Chao, J.D. Ward Jr., and R.G. Sands, “Charpy impact energy, fracture toughness and ductile-brittle transition temperature of dual phase 590 Steel”, Materials and Design, vol. 28, no. 2, pp. 551-557, 2007, doi: 10.1016/j.matdes.2005.08.009.
• [22] Y. Dai and P. Marmy, “Charpy impact tests on martensitic/ferritic steels after irradiation in SINQ target-3”, Journal of Nuclear Materials, vol. 343, no. 1-3, pp. 247-252, 2005, doi: 10.1016/j.jnucmat.2004.12.020.
• [23] L. Toth, H.P. Rossmanith, and T.A. Siewert, “Historical Background and Development of the Charpy Test”, in From Charpy to Present Impact Testing. ESIS Publication 30 – Proceedings of the Charpy Contenary Conference held in Poitiers, France, 2-5 October 2001, D. François and A. Pineau, Eds. Elsevier, 2002, pp. 3-19.
• [24] P. Zajdel, “Interpretacja rezultatów próby udarności oprzyrządowanym młotem Charpy’ego na potrzeby oceny właściwości stali konstrukcyjnych (Interpretation of the results of instrumented impact Charpy test for the purpose of assessing the properties of structural steel)”, Inżynieria i Budownictwo, no. 7, pp. 341-344, 2020.
• [25] M. Maślak, M. Stankiewicz, and P. Zajdel, “Kruchość wybranych stali konstrukcyjnych po symulowanej ekspozycji pożarowej (The brittleness of selected structural steeel grades specified after a simulated fire exposure)”, Inżynieria i Budownictwo, no. 5-6, pp. 232-239, 2022.
• [26] E. Tasak and A. Ziewiec, Spawalność materiałów konstrukcyjnych. Tom 1. Spawalność stali. Kraków: Wydawnictwo JAK, 2009.
• [27] ISO 14556:2023 Metallic materials – Charpy V-notch pendulum impact test – Instrumented test method. International Organization for Standardization, 2023.
• [28] K. Ye and F. Ozaki, “Impact fracture energy of steel welded connections in fire and post-fire”, Journal of Constructional Steel Research, vol. 170, art. no. 106120, 2020, doi: 10.1016/j.jcsr.2020.106120.
• [29] K.Ye, F. Ozaki, and M. Knobloch, “Impact fracture energies of cold-formed steel square hollowsection in and after fire”, Journal of Constructional Steel Research, vol. 183, art. no. 106740, 2021, doi: 10.1016/j.jcsr.2021.106740.
• [30] J. Nikolaou and G.D. Papadimitriou, “Microstructures and mechanical properties after heating of reinforcing 500 MPa class weldable steels produced by various processes (Tempcore, microalloyed with vanadium and work-hardened)”, Construction and Building Materials, vol. 18, no. 4, pp. 243-254, 2004, doi: 10.1016/j.conbuildmat.2004.01.001.
• [31] M. Hirohata, Y. Takashima, and F. Minami, “Characteristic of Charpy Absorbed Energy for Steel Bridge Member with Fire Damage”, Quarterly Journal of the Japan Welding Society, vol. 35, no. 2, pp. 122-126, 2017, doi: 10.2207/qjjws.35.122s.
• [32] M. Koufu, K. Mika, and I. Fuyuki, “A study on steel mechanical property considering heating history temperature and cooling method. Part V – effect of steel type on impact properties”, in Summaries of Technical Papers of Annual Meeting. Architectural Institute of Japan, Fire Safety, 2017, pp. 171-172.
• [33] K. Sugimoto, S. Kintou, M. Koufu, J. Haruhata, K. Nishimura, and J. Suzuki, “A study on steel mechanical property considering heating history temperature and cooling method. Part VI – effect of steel type onmicrostructure”, in Summaries of Technical Papers of Annual Meeting. Architectural Institute of Japan, Fire Safety, 2017, pp. 173-174.
• [34] S.K. Dhua, D. Mukerjee, and D.S. Sarma, “Influence of thermomechanical treatments on the microstructure and mechanical properties of HSLA-100 steel plates”, Metallurgical and Mechanical Transactions A: Physical Metallurgy and Material Science, vol. 34, pp. 241-253, 2003, doi: 10.1007/s11661-003-0326-3.
• [35] D. Rasouli, S. Khameneh, A. Akbarzadeh, and G.H. Daneshi, “Effect of cooling rate on the microstructure and mechanical properties of microalloyed forging steel”, Journal of Metarials Processing Technology, vol. 206, no. 1-3, pp. 92-98, 2008, doi: 10.1016/j.jmatprotec.2007.12.006.
• [36] B.K. Panigrahi, “Microstructure-mechanical property relationship for a Fe/Mn/Cr rocks bolt reinforcing steel”, Journal of Material Engineering and Performance, vol. 19, pp. 885-893, 2010, doi: 10.1007/s11665-009-9540-5.
• [37] L. Ceschini, A. Marconi, C. Martini, A. Morri, and A.D. Schino, “Tensile and impact behavior of a microalloyed medium carbon steel: effect of the cooling condition and corresponding microstructure”, Materials & Design, vol. 45, pp. 171-178, 2013, doi: 10.1016/j.matdes.2012.08.063.
• [38] A. Ghosh and M. Ghosh, “Tensile and impact behavior of thermos mechanically treated and microalloyed medium carbon steel bar”, Construction and Building Materials, vol. 192, pp. 657-670, 2018, doi: 10.1016/j.conbuildmat.2018.10.098.
• [39] PN-EN ISO 6508-1:2007 Metale – Pomiar twardości sposobem Rockwella – Część 1: Metoda badań [skale A, B, C, D, E, F, G, H, K, N, T] (Metallic materials – Rockwell hardness test – Part 1: Test method [scales A, B, C, D, E, F, G, H, K, N, T]). Warszawa, PKN, 2007.
• [40] PN-EN ISO 6506-1:2008 Metale – Pomiar twardości sposobem Brinella – Część 1: Metoda badań (Metallic materials – Brinell hardness test – Part 1: Test method). Warszawa, PKN, 2008.
• [41] PN-EN ISO 6507-1:2007 Metale – Pomiar twardości sposobem Vickersa – Część 1: Metoda badań (Metallic materials – Vickers hardness test – Part 1: Test method). Warszawa, PKN, 2007.
• [42] https://www.bossard.com/pl-en/assembly-technology-expert/technical-information-and-tools/online-calculators-and-converters/hardness-conversion/. [Accessed: 13 Jun. 2024].