高强度结构钢材Q460-C低温冲击韧性试验研究

EXPERIMENTAL STUDY ON THE IMPACT TOUGHNESS OF Q460-C HIGH-STRENGTH CONSTRUCTION STEEL AT LOW TEMPERATURE

高强度钢材在建筑行业中逐渐被应用,而随着钢材强度的增大,其韧性性能会有一定程度的退化,特别是在低温环境中更加明显。因此,有必要研究高强度建筑钢材的冲击韧性。通过对14 mm厚的高强钢材Q460-C进行低温下的冲击韧性试验,并将其夏比冲击功值与60,90,120,150 mm厚Q345的AKV值进行比较分析。结果显示,Q460-C的冲击韧性随温度的降低而下降,在20～-20℃,14 mm厚Q460-C钢材的低温冲击功值依次低于同温度下的150,120,90,60 mm厚Q345的AKV值,在低于―20℃时,Q460钢材的强度对其低温脆性的影响没有Q345钢材的厚度对其低温脆性的影响明显。同时,还利用Boltzmann函数对试验结果进行拟合分析,得到Q460-C钢材的韧脆转变温度为-11.1℃;最后对不同温度点下的冲击试件断口进行扫描电镜分析,观察到-20℃下冲断的试件断口形貌有相当的脆性特征,基本已完成了从韧性向脆性断裂的转变。试验表明,Q460-C钢材的低温脆性特征明显,应引起足够重视。

High strength steel has been gradually applied in construction industry.As the strength of steel increases,the property of toughness degrades to some extent,particularly in the case of application at low temperature.Therefore,it is necessary to study the impact toughness of high strength steel.Impact toughness tests of 14 mm thick Q460-C steel at low temperature were performed,Charpy impact power level was compared with that of 60,90,120,and 150 mm thick Q345 steel at the same temperature respectively,besides the scanning electronic microscope of the Charpy-type specimen fracture surfaces with different temperature points were analyzed.And the results showed that：1）The impact toughness of Q460-C steel decrease with the descending temperature;2）Between 20 ℃ and-20 ℃,the low temperature impact power level of 14 mm thick Q460-C was lower than that of 150,120,90 mm and 60 mm thick Q345 at the same temperature;3）The influence of steel strength on low temperature brittleness of Q460-C was less obvious than that of steel depth on that of Q345;4）The fracture appearances of Charpy-type specimens of Q460-C,which break at-20 ℃ had finished the transition form ductile to brittle on the whole,with a large of significant brittle characteristics.Meanwhile,a Boltzmann function fit analysis was made on Charpy impact test results of Q460-C,obtaining-11.1 ℃ as the brittle ductile transition temperature.Test results showed that the low temperature brittleness of Q460-C and its welding seam were apparent,to which much attention should be paid.