WSM50C钢的裂尖塑性损伤与断裂

The Ductile Damage and Fracture at The Crack Tip in Steel WSM50C

本文利用一组紧凑拉伸(CT)试样。测定了WSM50C高炉钢板材料的J_(?)阻力曲线和断裂韧性J_(IC),并采用液氮冲剖试样技术,在扫描电镜下研究了裂纹尖端附近材料塑性损伤与断裂的细观力学行为。观测研讨了内部空穴的演化规律。结果表明,裂尖附近的塑性损伤与断裂可以用细观空穴扩张比参数R/R_0来描述。当J<J_(IC)时,随着载荷的增加,裂尖逐步饨化,R/R_0单调增加;当J≥J_(IC)时,R/R_0达到临界值R_C/R_0后即保持不变。说明临界空穴扩张比R_C/R_0是表征材料塑性破坏的材料常数。

The J_R resistance curve and fracture toughness J_(IC) were experimentally determined from a series of CT specimens made of steel WSM50C. And then the specimens were cut by using the technique of brittle splitting in liquid nitrogen, the void growth processes at the crack tip regions were observed and measured by Scanning Electron Microscope, so that the mechanical behavior of ductile damage and fracture was exposed both macroscopically and microscopically. The results show that the microform parameter of void growth ratio, R/R_0, can be effectively employed to characterize the damage and fracture behavior at the region of the speeimen's crack tip. The ratio R/R_0 monotonically increases with the increasing of load when J is below J_(IC) and rereads constant when J is equal to or over J_(IC). So it can be considered that the critical void growth ratio R_C/R_0, as a microscopic fracture toughness, can be employed to predict both initiation and propagation of the crack.