国产Q550高强钢高温力学性能试验研究

Experimental Research on Mechanical Properties of Domestic High Strength Steel Q550 at Elevated Temperatures

摘要:

通过稳态拉伸法对国产Q550高强钢高温力学性能进行试验研究,得到20~800 ℃下钢材的试验现象、力学性能参数、应力-应变关系曲线,并将所得试验结果与国内外相关规范和研究成果对比。试验表明：不同温度下试件破坏时表面及断口形貌区别明显；300 ℃后随着温度升高,弹性模量、屈服强度、极限强度下降,应力-应变关系曲线的弹性段和强化段缩短,下降段趋于平缓。450 ℃内高温对断后伸长率影响不大,此后随温度升高断后伸长率急剧增大。现有钢材高温力学性能参数模型对国产Q550高强钢并不适用。因此,分别采用多项式模型和美国国家标准与技术研究院的钢材高温通用材料模型进行拟合,得到高温下Q550高强钢力学性能参数的数学模型。

Abstract:

An experimental study was carried out to investigate the mechanical properties of domestic high strength steel Q550 at elevated temperatures. Steady-state tests were conducted on specimens at high temperatures ranged from 20 ℃ to 800 ℃. The experimental phenomena, mechanical properties and stress-strain curves at different temperatures were obtained. The tests results were compared with the reduction factors determined by current standards and by other researchers. The results showed that, the surface and fracture of the specimens at different temperatures were significantly different. When the temperature of specimen was higher than 300 ℃, the elastic modulus, yield strength and ultimate strength decreased with the increase of temperature, the linear elasticity and strain-hardening stage of the stress-strain curves shortened, and the descending stage tended to be gentle. The high temperature had little influence on elongation when the temperature was below 450 ℃. The current parameter models of high temperature mechanical properties were not applicable for Q550 steel. In order to obtain the mathematical models for mechanical properties of Q550, polynomial model and high temperature material model proposed by National Institute of Standards and Technology were employed.