不同冷却方式下S280GD+Z钢材高温后力学性能试验研究

Experimental research on mechanical properties of S280GD+Z steel after high temperature under different cooling methods

为研究高温及冷却方式对不同厚度S280GD+Z钢材力学性能的影响,通过高温、冷却和拉伸试验,对经历20℃~800℃高温后1.0mm、1.5mm和2.0mm厚S280GD+Z钢材在自然冷却和浸水冷却方式下的力学性能进行了试验研究。结果表明:受火温度和冷却方式对S280GD+Z钢材表面特征和破坏模式影响较大,对其弹性模量影响较小;温度低于600℃时,受火温度和冷却方式对S280GD+Z钢材屈服强度、极限强度和伸长率影响较小;温度超过600℃后,自然冷却方式下,不同厚度S280GD+Z钢材屈服强度和极限强度均随受火温度提高而降低;浸水冷却方式下,1.5mm和2.0mm厚S280GD+Z钢材屈服强度和极限强度随受火温度的提高而增大,伸长率随受火温度的提高而降低。将不同厚度S280GD+Z钢材高温后力学性能与其他冷成型钢材比较,认为不同钢材高温后力学性能差异较大。所建立力学参数与受火温度间数学模型可为采用S280GD+Z钢材的冷弯薄壁型钢结构火灾后安全评价与加固设计提供参考。

In order to study the effects of high temperature and cooling methods on mechanical properties of S280GD+Z steel,an experimental research on mechanical properties of S280GD+Z steel with thickness of 1.0mm,1.5mm and 2.0mm under cooling in air and cooling in water after high temperature of 20℃~800℃is carried out by procedures of high temperature,cooling and tensile tests.The results indicate that fire temperature and cooling methods have a great influence on the surface characteristics and failure modes of S280GD+Z steel,but no obvious influence on elastic modulus.When the temperature is lower than 600℃,the fire temperature and cooling methods have little effect on the yield strength,ultimate strength and elongation of S280GD+Z steel.When the temperature exceeds 600℃,under the cooling in air,the yield strength and ultimate strength of S280GD+Z steel with different thicknesses decrease with the fire temperature increases.Under the cooling in water,the yield strength and ultimate strength of S280GD+Z steel with thickness of 1.5mm and 2.0mm under cooling in water increase with the increase in fire temperature,while the elongation of S280GD+Z steel decreases with the increase in fire temperature.The mechanical properties of S280GD+Z steel with different thicknesses after high temperature are compared with other cold⁃formed steels,it is found that the mechanical properties of different steels after high temperature are quite different.The mathematical model established between mechanical parameters and fire temperatures can provide reference for post⁃fire safety evaluation of cold⁃formed thin⁃wall steel structures using S280GD+Z steel.