摘要
采用ZL-2超强脉冲放电装置实现了7A04超硬铝合金试件中斜裂纹的止裂实验.在瞬间超强脉冲电流作用下,裂尖前缘发生了强烈的绕流热集中现象,斜裂纹裂尖附近金属熔化,钝化了裂尖,阻止了干线裂纹源的开裂趋势.对止裂前后裂尖附近金属组织进行了显微观察,并对止裂前后裂纹附近的断口进行了对比分析;在万能材料试验机上对试件进行了拉伸力学性能对比测试.研究表明:在斜裂纹止裂瞬间,裂尖熔化,同时实现了组织超细化,提高了裂纹的扩展功,改善了试件的抗拉力学性能.
The oblique crack arrest of 7A04 super hardness aluminium was studied by super pulse current discharge with home- made equipment ZL-2. Under the super impulse current discharge, there is a strong detouring phenomenon at the crack tip. The metal melt around the oblique crack tip passivates the crack tip and inhibits the cracking trend of main crack source. The microstructures of the aluminium alloy before and after crack arrest were observed by metallographic microscope, and the fracture morphologies were compared macroscopically and microcosmically. Tension tests of samples with an oblique crack before and after crack arrest were done by using a PC-control universal tester. The results indicates that on the moment of crack arrest, the metal around the crack tip melts, the microstructure at the crack tip appears super refine, the work of crack expansion increases, and the tensile mechanical properties of specimens are improved.
出处
《北京科技大学学报》
EI
CAS
CSCD
北大核心
2009年第2期203-206,214,共5页
Journal of University of Science and Technology Beijing
基金
国家自然科学基金资助项目(No.50675190)
关键词
超硬铝合金
裂纹
止裂
微观组织
脉冲放电
super hardness aluminium alloy
crack
crack arrest
microstructure
pulse current discharge
