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Mechanical properties of 600 MPa highstrength bars after exposure to high temperatures(PDF)

长安大学学报（自然科学版）[ISSN:1006-6977/CN:61-1281/TN]

Issue:
2018年06期
Page:
89-91
Research Field:
桥梁与隧道工程
Publishing date:

Info

Title:
Mechanical properties of 600 MPa highstrength bars after exposure to high temperatures
Author(s):
SUN Chuanzhi;  LI Aiqun;  MIAO Changqing;  QIAO Yan;  DONG Xue
(1. School of Architecture and Engineering, Suqian College, Suqian 223800, Jiangsu, China； 2. School ofCivil Engineering， Southeast University， Nanjing 210096， Jiangsu, China； 3． School of Civil andTransportation Engineering， Beijing University of Civil Engineering and Architecture， Beijing 100044， China；4. Suqian Housing and UrbanRural Development Bureau, Suqian 223800, Jiangsu, China)
Keywords:
bridge engineering;  highstrength bar;  after exposure to high temperature;  cooling method;  internal tissue;  mechanical property
PACS:
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DOI:
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Abstract:
To examine the influence of different heating temperatures and cooling methods on the mechanical properties of 600 MPa highstrength bars, 27 groups of 600 MPa highstrength bars were subjected to the following sequence of experimental treatments. The bars were heated to high temperatures and cooled by different cooling methods. Static tensile tests were performed on the bars, and the longitudinal tissue of the resulting fractures was observed. The results were compared with those from other grades of reinforcement. Based on the experimental data obtained, formulas for estimating the changes in mechanical properties with temperature under different cooling modes were derived. The results show that the cooling mode has no effect on the basic tissue at low temperatures, but the influence of the different cooling methods on the tissue is greater at high temperatures. When the temperature is less than 550 ℃, the mechanical properties of the steel bars remain basically unchanged, and when the temperature is 625 ℃, three parameters (yield strength, limit strength, and elastic modulus) show declining trends, but the elongation rate is basically unchanged. When the temperature is greater than 775 ℃, the different cooling methods significantly affect the mechanical properties, especially when the cooling bar is immersed in water. In particular, the test specimen has no neck shrinkage, the section is relatively neat, and the stressstrain curve has no yield platform. The yield strength and limit strength increase, and the elongation decreases rapidly. When the temperature is 925 ℃, the elongation is only 1.7%, and the damage indicates obvious brittleness. Although the elongation of the specimens exposed to the other two cooling methods is about 30%, the mechanical properties vary substantially. 10 figs, 20 refs.

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Last Update: 2018-12-18