论文部分内容阅读
关于钢结构的脆性破坏事故的记载可以追溯到1879年或更早一些。而随着材料强度的提高以及焊接工艺的应用,脆性破坏的事故也在增多。因此对脆性破坏进行了广泛的研究。铁素体钢存在着二种断裂机理,即以沿一定的结晶学平面解理的解理断裂和以显微孔隙的产生和聚集为机理的范性断裂。在温度由高而降低时,就由范性断裂逐步转变到解理断裂。考查脆性破坏事故可以看到具有下述的特点:破坏时的名义应力较低,通常是低于设计应力或材料的屈服强度;破坏前没有或者只有局部的极小的塑性变形;断口是平直而光亮,即一般称为解理断口;破坏一旦发生便以极高的速度扩展
Records of brittle failure of steel structures can be traced back to 1879 or earlier. With the increase of material strength and the application of welding technology, the number of accidents of brittle failure is also increasing. Therefore, brittle failure has been extensively studied. There are two kinds of fracture mechanism in ferritic steels: cleavage fracture cleaved along a certain crystallographic plane and normal fracture caused by microporosity generation and accumulation. When the temperature decreases from high to low, the transition from normal to cleavage faulting. Examination of the brittle failure can be seen with the following characteristics: The nominal stress at break is low, usually lower than the design stress or the yield strength of the material; there is no or only partial minimum plastic deformation before failure; the fracture is straight The light, which is generally called cleavage fracture; destruction in the event of an extremely high rate of expansion