低温下高强钢缺口板断裂试验

Fracture experiment of structural steel notched plates at low temperature

为研究低温下结构钢断裂机理及抗断设防,在冷脆转换温度下(-45±2℃)对10个16mm厚Q345钢材缺口板进行了单向拉伸断裂试验,研究了缺口尺寸(a、2b)对结构钢断裂模式的影响。结果表明:试件断裂于刻痕心部,断口心部有一条清晰的起裂棱,宏观断面大致垂直于加载方向;试件缺口愈尖锐或缺口比率(2b/a)愈小,断裂延性愈差。材性试验曲线展现了较明显的屈服、强化和颈缩现象;高强钢低温下的强屈比、伸长率均满足规范对建筑用钢材塑性设计的要求。从整体上看,试验数据离散性较小。

To study rupture mechanism and fracture design of structural steel at low temperature,fracture experiment was performed on 10 notched plates with the thickness of 16 mm at the ductile-brittle transition temperature（-45±2 ℃）.The load-displacement curves of notched plates were recorded accurately and the experiment results indicated that the first crack initiated at the notched edge and expanded rapidly along the width of the plates.Finally,the specimens fractured at the critical section and there was a clear edge,and the more the gap was sharp,the more the fracture ductile was poor.The stress-strain curve tested at low temperature exhibits the character of yielding,hardening and necking of high strength steel.The ratio of ultimate strength to yield strength and ductility,at low temperature meet with the requirement in plastic design for structural steel.Generally,the data of this experiment were stability and qualitatively revealed fracture rules.