国产Q355钢材高温冷却后力学性能试验研究

张春涛; 李海; 于伟

doi:10.13206/j.gjgS22110104

国产Q355钢材高温冷却后力学性能试验研究

doi: 10.13206/j.gjgS22110104

张春涛^1,2,
李海¹,
于伟^3,4

1. 西南科技大学土木工程与建筑学院, 四川绵阳 621010;
2. 工程材料与结构冲击振动四川省重点实验室, 四川绵阳 621010;
3. 桂林理工大学土木与建筑工程学院, 广西桂林 541004;
4. 广西建筑新能源与节能重点实验室, 广西桂林 541004

基金项目:

国家自然科学基金项目(51868013,51508482)。

详细信息

作者简介:
张春涛,男,1983年出生,博士,教授。Email:zhangchuntao1@126.com

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出版历程
- 收稿日期: 2022-11-01
- 网络出版日期: 2023-05-24
- 刊出日期: 2023-03-25

Experimental Research on Post-Fire Mechanical Properties of Domestic Q355 Steel After Cooling from High Temperature

1. College of Civil Engineering and Architecture, Southwest University of Science and Technology, Mianyan 621010, China;
2. Shock and Vibration of Engineering Materials and Structures Key Laboratory of Sichuan Province, Mianyang 621010, China;
3. College of Civil and Architecture Engineering, Guilin University of Technology, Guilin 541004, China;
4. Guangxi Key Laboratory of New Energy and Building Energy Saving, Guilin 541004, China

摘要

摘要: Q355作为一种新型钢材,凭借其优良的力学性能在我国建筑领域中逐渐广泛运用,但其存在抗火性差的致命缺点,对钢结构建筑存在较大的危险。通过对火灾后的钢结构建筑进行安全性鉴定和承载能力评估,可有效避免因拆除重建而产生的浪费,对其中能予以修复或替换的构件采取相应措施,能较大地节约经济成本。因此,有必要对火灾后的Q355钢材进行残余力学性能研究。为了真实模拟Q355钢材经历火灾及灭火后发生的情形,设置200~900℃及自然冷却、浸水冷却等条件来模拟火灾,并将高温后的Q355钢材进行力学性能试验。借助高温炉、万能试验机及电子引伸计等设备,获得高温冷却后Q355钢材的应力-应变曲线和力学性能参数(屈服强度、抗拉强度、屈强比、弹性模量和伸长率等),并对应力-应变曲线和力学参数受温度及冷却方式的影响规律进行分析,对比分析Q355钢材与Q235、Q460和Q690钢材高温后力学性能的变化规律,利用ORIGIN数据处理软件拟合出Q355钢材在不同冷却方式作用影响下的力学性能数学模型。结果表明:Q355钢材在自然冷却和浸水冷却方式下具有不同的表观特征、破坏模式和力学性能特征;Q355钢材的表面碳化程度随温度的升高而逐渐加深,暴露温度超过600℃时,碳化现象愈加明显,甚至在浸水冷却时,碳化表皮出现剥落;温度未超过600℃时,表观形貌变化特征较小且拉伸试件变形程度较轻,与未经高温试件的表观及变形相似;另外,600℃同时也是Q355钢材残余力学性能改变的临界温度,当温度低于600℃时,Q355钢材力学参数受温度和冷却方式的影响小;温度超过600℃后,Q355钢材力学性能参数随温度和冷却发生改变而显著变化,自然冷却后Q355钢材的屈服强度、抗拉强度和弹性模量均随温度升高而减小,伸长率却随温度升高而增大;温度超过600℃后,Q355钢材经浸水冷却后屈服强度和抗拉强度随温度升高而增大,弹性模量和伸长率却随温度的升高而降低。基于试验结果,建立不同冷却方式下Q355力学性能参数随温度变化的数学模型。
- Q355钢材 /
- 高温 /
- 力学性能 /
- 冷却方式 /
- 数学模型
Abstract: As a new type of steel, Q355 has been widely used in the field of construction due to its excellent mechanical properties. However, it has the fatal disadvantage of poor fire resistance, which is dangerous to steel structure buildings. Through the safety appraisal and bearing capacity evaluation of steel structure buildings after fire, the waste caused by demolition and reconstruction can be effectively avoided, and corresponding measures can be taken to repair or replace the components, which can greatly save economic costs. Therefore, it is necessary to study the residual mechanical properties of Q355 steel after fire. In order to simulate the situation of Q355 steel after fire and fire extinguishing, the conditions of 200 to 900℃, natural cooling and water cooling were set to simulate the fire, and the mechanical properties of Q355 steel after high temperature were tested. With the help of high temperature furnace, universal testing machine and electronic extensometer, the stress-strain curve and mechanical properties parameters (yield strength, tensile strength, ratio of yield strength to ultimate tensile strength, elastic modulus and elongation, etc) of Q355 steel after high temperature cooling were obtained. The influence of temperature and cooling method on the stress-strain curve and mechanical parameters was analyzed. The mechanical properties of Q355 steel and Q235, Q460 and Q690 steel after high temperature were compared and analyzed. The mathematical model of mechanical properties of Q355 steel under different cooling methods was fitted by ORIGIN data processing software. It was found that there were significant differences in the different apparent characteristics, failure modes and mechanical properties of Q355 steel for different temperatures and cooling methods. The surface carbonization degree of Q355 steel gradually deepened with the increase of temperature. When the exposure temperature exceeds 600℃, the carbonization phenomenon become more obvious, and even when immersed in water for cooling, the carbonization skin peeled off. When the temperature does not exceed 600℃, the apparent morphology change characteristics were small and the deformation degree of the tensile specimen was light, which was similar to the appearance and deformation of the specimen without high temperature. In addition, 600℃ was also the critical temperature for the change of residual mechanical properties of Q355 steel. When the temperature was lower than 600℃, the effect of temperatures and cooling methods on the mechanical properties of Q355 steel was negligible. However, when the temperature was higher than 600℃, temperatures and cooling methods exerted a distinct influence on the mechanical properties of Q355 steel. After air cooling, the yield strength, tensile strength, and elastic modulus of Q355 steel decreased with the increase in temperature, but the ultimate elongation increased with the increase in temperature. After water cooling, the yield strength and tensile strength of Q355 steel increased with the increase in temperature, while the elastic modulus and ultimate elongation decreased with the increase in temperature. Furthermore, the predictive equations were proposed to determine the post-fire material properties of Q355 steel for cooling in air and cooling in water.
- Q355 steel /
- high temperature /
- mechanical property /
- cooling method /
- predictive equations

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