Residual Mechanical Properties of High-Strength Steel Bolts after Exposure to Elevated Temperature

Yahyai, Mahmood; Kodur, Venkatesh; Rezaeian, Abbas

doi:10.1061/(asce)mt.1943-5533.0002416

Cited by 19 publications

(7 citation statements)

References 23 publications

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“…Bolts that underwent such a heating cycle permanently lose their original strength properties. This, in general, confirms the observations made by Kirby [ 1 , 2 ], Kodur et al [ 5 , 6 ], and Yahyai [ 7 ]. However, each of them in their considerations ignored the effect of rapid cooling, which is a natural consequence of the fire-fighting action, as well as the related consequences concerning both the microstructure and mechanical properties of the tested bolts.…”

Section: Discussionsupporting

confidence: 92%

“…However, each of them in their considerations ignored the effect of rapid cooling, which is a natural consequence of the fire-fighting action, as well as the related consequences concerning both the microstructure and mechanical properties of the tested bolts. Kodur et al [ 5 , 6 ], similar to Yahyai et al [ 7 ] did not focus on detailed microstructural studies, and they only tried to link the bolt failure model with the macroscopic image of the fracture surface. In the case of screws naturally cooled in the air after the annealing process at a temperature exceeding 600 °C, similar to observations of Sajid et al [ 10 ], the significant growth of pearlite and ferrite grains was observed leading to a reduction in the ultimate tensile strength.…”

Section: Discussionmentioning

confidence: 99%

“…They made an attempt to explain how cracks propagate depending on the microstructure of the bolt material. In [ 7 ], Yahyai et al undertook similar research as in [ 6 ], focusing on bolts with a higher strength grade—10.9. The effects of a heating temperature, the chemical composition of the charge steel (raw material), and production process parameters on durable mechanical properties were subject to an in-depth analysis.…”

Section: Introductionmentioning

confidence: 99%

“…It is worth mentioning that the available sources of knowledge present some research results relating only to two strength classes of bolts—grade 8.8 [ 1 , 2 , 4 ] and grade 10.9 [ 3 , 7 ]. The results obtained for bolts of grade 10.9 are qualitatively and quantitatively comparable to those presented for bolts of grade 8.8.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Fire Temperature and Exposure Time on High-Strength Steel Bolts Microstructure and Residual Mechanical Properties

Król

Wachowski

2021

Materials

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In this study, the influence of different fire conditions on tempered 32CrB3 steel bolts of Grade 8.8 was investigated. In this research different temperatures, heating time, and cooling methods were correlated with the microstructure, hardness, and residual strength of the bolts. Chosen parameters of heat treatments correspond to simulated natural fire conditions that may occur in public facilities. Heat treated and unheated samples cut out from a series of tested bolts were subjected to microstructural tests using light microscopy (LM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), XRD phase analysis, and the quantitative analysis of the microstructure. The results of the microstructure tests were compared with the results of strength tests, including hardness and the ultimate residual tensile strength of the material (UTS) in the initial state and after the heat treatments. Results of the investigations revealed considerable microstructural changes in the bolt material as a result of exposing it to different fire conditions and cooling methods. A conducted comparative analysis also showed a significant effect of all such factors as the temperature level of the simulated fire, its duration, and the fire-fighting method on the mechanical properties of the bolts.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Fire Temperature and Exposure Time on High-Strength Steel Bolts Microstructure and Residual Mechanical Properties

Król

Wachowski

2021

Materials

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show abstract

“…They made an attempt to explain how cracks propagate depending on microstructure of the bolt material. In [7], Yahyai et al undertook a similar research as in [6], focusing on bolts with a higher strength grade -10.9. The effects of a heating temperature, a chemical composition of the charge steel (raw material) and production process parameters on durable mechanical properties were subject to an in-depth analysis.…”

Section: Introductionmentioning

confidence: 99%

Effect of Fire Temperature and Exposure Time on High-strength Steel Bolts Microstructure and Residual Mechanical Properties

Król¹,

Wachowski²

2021

Preprint

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The article presents results of research consisting in an attempt to assess the influence of temperature, heating time and cooling method on microstructure and residual strength properties of steel previously tempered during the production process. Simulated environmental conditions to which high-strength bolts, commonly used in steel construction, were subjected, were intended to reflect conditions of a natural fire that may occur in public facilities where the obligation to ensure safety of users and rescue teams is of key importance, also required by law. Furthermore, the tests carried out also comprised a simulated effect of a rescue and firefighting operation using shock, rapid cooling of some of the heated bolts. Samples cut out from the tested bolts, after they were properly prepared, were subjected to microstructural tests using light microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), phase analysis with the use of an X-ray diffractometer (XRD) and quantitative analysis of the microstructure involving, inter alia, measuring the surface area of grains, their equivalent diameter and mean diameter. As a result of the tests, considerable microstructure changes were identified occurring in the bolt material as a result of exposing it to fire conditions, leading to a change in key, from the point of view of structural safety, mechanical properties. The results of the microstructure tests were compared with the results of previous strength tests, including hardness of the material after the heat treatment and the residual tensile strength of the material Rm. A conducted comparative analysis showed a significant effect of all such factors as the temperature level of the simulated fire, its duration and the fire-fighting method on the mechanical properties of bolts. Results obtained were provided with required comments and the concept of using the microstructure for the post-fire assessment of steel structures was referred to.

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Fire Response of Steel Beams With Bolted Flange Plate Connections

Ebrahimzadeh

Rezaeian

2021

Fire Technol

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Residual Mechanical Properties of High-Strength Steel Bolts after Exposure to Elevated Temperature

Cited by 19 publications

References 23 publications

Effect of Fire Temperature and Exposure Time on High-Strength Steel Bolts Microstructure and Residual Mechanical Properties

Effect of Fire Temperature and Exposure Time on High-Strength Steel Bolts Microstructure and Residual Mechanical Properties

Effect of Fire Temperature and Exposure Time on High-strength Steel Bolts Microstructure and Residual Mechanical Properties

Fire Response of Steel Beams With Bolted Flange Plate Connections

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