Mechanical properties of ultra-high strength (Grade 1200) steel tubes under cooling phase of a fire

An experimental investigation

Fatemeh Azhari, Amin Heidarpour, Xiao Ling Zhao, Christopher Hutchinson

Research output: Contribution to journalArticleResearchpeer-review

35 Citations (Scopus)

Abstract

There has recently been a growing trend towards using ultra-high strength steel (UHSS) in many engineering applications. However, few researches have focused on the mechanical properties of this kind of steel at elevated temperatures. In this study, the mechanical properties of UHSS at temperatures characteristic of fire and after cooling from fire temperatures, are studied experimentally. The specimens taken from UHSS tubes are subjected to fire temperatures of up to 600ºC and tensile tests are carried out both at elevated temperatures and after the specimens were cooled to room temperature. As expected, the strength of the UHSS specimens decreases significantly when tested under fire temperatures of 450ºC and 600 ?C. However, the strength of the UHSS is also considerably reduced after cooling down from high fire temperatures to room temperature. The stress-strain curves, strength and ductility of the UHSS tube specimens are discussed. Furthermore, in order to perform a comparison study, the stress-strain curves for three different grades of steel tubes including UHSS, high strength steel (HSS) and Mild steel (MS) tubes are presented and compared. It is shown that the reduction in the strength of the UHSS after cooling from fire temperatures of up to 600ºC does not occur to the same extent for HSS and MS steels. The effect of the cooling rate after exposure to fire temperatures on the mechanical properties of UHSS tube specimens is also investigated. Micro-structure examination is conducted using optical and scanning electron microscopy (SEM) and the room temperature strength reduction in the UHSS after exposure to the fire temperatures is discussed in terms of the effect on the steel microstructure. A recommendation has been made for separating studies of the effect of simulated fire temperatures on the residual strength of steel into two classes (low and high temperature), depending on whether a critical maximum temperature (which depends on alloy composition) is exceeded and the science underlying this recommendation has been discussed.
Original languageEnglish
Pages (from-to)841 - 850
Number of pages10
JournalConstruction and Building Materials
Volume93
DOIs
Publication statusPublished - 2015

Keywords

  • Ultra-high strength steel
  • Fire
  • Cooling
  • Stress–strain curve
  • Steel tube
  • Cooling rate
  • Micrograph

Cite this

@article{f90abec51d49469c81ffefd8ab47e620,
title = "Mechanical properties of ultra-high strength (Grade 1200) steel tubes under cooling phase of a fire: An experimental investigation",
abstract = "There has recently been a growing trend towards using ultra-high strength steel (UHSS) in many engineering applications. However, few researches have focused on the mechanical properties of this kind of steel at elevated temperatures. In this study, the mechanical properties of UHSS at temperatures characteristic of fire and after cooling from fire temperatures, are studied experimentally. The specimens taken from UHSS tubes are subjected to fire temperatures of up to 600ºC and tensile tests are carried out both at elevated temperatures and after the specimens were cooled to room temperature. As expected, the strength of the UHSS specimens decreases significantly when tested under fire temperatures of 450ºC and 600 ?C. However, the strength of the UHSS is also considerably reduced after cooling down from high fire temperatures to room temperature. The stress-strain curves, strength and ductility of the UHSS tube specimens are discussed. Furthermore, in order to perform a comparison study, the stress-strain curves for three different grades of steel tubes including UHSS, high strength steel (HSS) and Mild steel (MS) tubes are presented and compared. It is shown that the reduction in the strength of the UHSS after cooling from fire temperatures of up to 600ºC does not occur to the same extent for HSS and MS steels. The effect of the cooling rate after exposure to fire temperatures on the mechanical properties of UHSS tube specimens is also investigated. Micro-structure examination is conducted using optical and scanning electron microscopy (SEM) and the room temperature strength reduction in the UHSS after exposure to the fire temperatures is discussed in terms of the effect on the steel microstructure. A recommendation has been made for separating studies of the effect of simulated fire temperatures on the residual strength of steel into two classes (low and high temperature), depending on whether a critical maximum temperature (which depends on alloy composition) is exceeded and the science underlying this recommendation has been discussed.",
keywords = "Ultra-high strength steel, Fire, Cooling, Stress–strain curve, Steel tube, Cooling rate, Micrograph",
author = "Fatemeh Azhari and Amin Heidarpour and Zhao, {Xiao Ling} and Christopher Hutchinson",
year = "2015",
doi = "10.1016/j.conbuildmat.2015.05.082",
language = "English",
volume = "93",
pages = "841 -- 850",
journal = "Construction and Building Materials",
issn = "0950-0618",
publisher = "Elsevier",

}

Mechanical properties of ultra-high strength (Grade 1200) steel tubes under cooling phase of a fire : An experimental investigation. / Azhari, Fatemeh; Heidarpour, Amin; Zhao, Xiao Ling; Hutchinson, Christopher.

In: Construction and Building Materials, Vol. 93, 2015, p. 841 - 850.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Mechanical properties of ultra-high strength (Grade 1200) steel tubes under cooling phase of a fire

T2 - An experimental investigation

AU - Azhari, Fatemeh

AU - Heidarpour, Amin

AU - Zhao, Xiao Ling

AU - Hutchinson, Christopher

PY - 2015

Y1 - 2015

N2 - There has recently been a growing trend towards using ultra-high strength steel (UHSS) in many engineering applications. However, few researches have focused on the mechanical properties of this kind of steel at elevated temperatures. In this study, the mechanical properties of UHSS at temperatures characteristic of fire and after cooling from fire temperatures, are studied experimentally. The specimens taken from UHSS tubes are subjected to fire temperatures of up to 600ºC and tensile tests are carried out both at elevated temperatures and after the specimens were cooled to room temperature. As expected, the strength of the UHSS specimens decreases significantly when tested under fire temperatures of 450ºC and 600 ?C. However, the strength of the UHSS is also considerably reduced after cooling down from high fire temperatures to room temperature. The stress-strain curves, strength and ductility of the UHSS tube specimens are discussed. Furthermore, in order to perform a comparison study, the stress-strain curves for three different grades of steel tubes including UHSS, high strength steel (HSS) and Mild steel (MS) tubes are presented and compared. It is shown that the reduction in the strength of the UHSS after cooling from fire temperatures of up to 600ºC does not occur to the same extent for HSS and MS steels. The effect of the cooling rate after exposure to fire temperatures on the mechanical properties of UHSS tube specimens is also investigated. Micro-structure examination is conducted using optical and scanning electron microscopy (SEM) and the room temperature strength reduction in the UHSS after exposure to the fire temperatures is discussed in terms of the effect on the steel microstructure. A recommendation has been made for separating studies of the effect of simulated fire temperatures on the residual strength of steel into two classes (low and high temperature), depending on whether a critical maximum temperature (which depends on alloy composition) is exceeded and the science underlying this recommendation has been discussed.

AB - There has recently been a growing trend towards using ultra-high strength steel (UHSS) in many engineering applications. However, few researches have focused on the mechanical properties of this kind of steel at elevated temperatures. In this study, the mechanical properties of UHSS at temperatures characteristic of fire and after cooling from fire temperatures, are studied experimentally. The specimens taken from UHSS tubes are subjected to fire temperatures of up to 600ºC and tensile tests are carried out both at elevated temperatures and after the specimens were cooled to room temperature. As expected, the strength of the UHSS specimens decreases significantly when tested under fire temperatures of 450ºC and 600 ?C. However, the strength of the UHSS is also considerably reduced after cooling down from high fire temperatures to room temperature. The stress-strain curves, strength and ductility of the UHSS tube specimens are discussed. Furthermore, in order to perform a comparison study, the stress-strain curves for three different grades of steel tubes including UHSS, high strength steel (HSS) and Mild steel (MS) tubes are presented and compared. It is shown that the reduction in the strength of the UHSS after cooling from fire temperatures of up to 600ºC does not occur to the same extent for HSS and MS steels. The effect of the cooling rate after exposure to fire temperatures on the mechanical properties of UHSS tube specimens is also investigated. Micro-structure examination is conducted using optical and scanning electron microscopy (SEM) and the room temperature strength reduction in the UHSS after exposure to the fire temperatures is discussed in terms of the effect on the steel microstructure. A recommendation has been made for separating studies of the effect of simulated fire temperatures on the residual strength of steel into two classes (low and high temperature), depending on whether a critical maximum temperature (which depends on alloy composition) is exceeded and the science underlying this recommendation has been discussed.

KW - Ultra-high strength steel

KW - Fire

KW - Cooling

KW - Stress–strain curve

KW - Steel tube

KW - Cooling rate

KW - Micrograph

UR - http://goo.gl/uoKGdv

U2 - 10.1016/j.conbuildmat.2015.05.082

DO - 10.1016/j.conbuildmat.2015.05.082

M3 - Article

VL - 93

SP - 841

EP - 850

JO - Construction and Building Materials

JF - Construction and Building Materials

SN - 0950-0618

ER -