结构钢材裂纹尖端张开位移的低温试验  

Experimental measurements of the crack tip opening displacement of structural steels at low temperature

作　　者：武延民[1] 王元清[1] 石永久[1] 江见鲸[1] 

机构地区：[1]清华大学土木工程系,北京100084

出　　处：《清华大学学报（自然科学版）》2005年第6期730-732,共3页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金资助项目(50078029)

摘　　要：目前对结构钢材低温脆性断裂的控制主要通过冲击韧性指标,难于获得定量的结果,因此,有必要对结构钢材的断裂指标进行低温测定。试验测定了结构钢材Q235A、Q345B和Q390E(屈服强度标准值分别为235MPa、345MPa和390MPa)在20～-70℃下12～48mm试样的裂纹尖端张开位移指标(CTOD),并分析了最大载荷CTOD特征值δm随温度和厚度的变化规律。结果表明,总的趋势是δm随着温度的降低而下降,其规律可以比较好的用Boltzmann函数描述;厚度增大,δm的总趋势降低,但在厚度12～24mm范围附近也会出现δm随厚度增加而上升的现象。Currents tests of brittle fracture for steel structures at low temperatures is based on the impact toughness, but accurate quantitative results are difficult to obtain. Therefore, measurements of the fracture toughness of structural steel are also used to evaluate brittle fracture. The current experiments measured the crack tip opening displacement (CTOD) of three structural steels, Q235A, Q345B and Q390E (their characteristic yield strengths are 235 MPa, 345 MPa and 390 MPa) for 12 mm to 48 mm thick slabs from 20 ℃ to -70 ℃. The results describe the variations of the CTOD at maximum load (δ_m) with temperature and thickness. The results show that δ_m decreases with decreasing temperature in a manner consistent with the Boltzmann function. δ_m also decreases with increasing thickness for thicher plates but increases between the 12 mmand 24 mm thicknesses.

关 键 词：结构钢材 裂纹尖端张开位移(CTOD) 低温 

分 类 号：TU313[建筑科学—结构工程]