摘要
根据DWTT试样断口中脆性区产生的原因不同,异常断口形貌分为三类:第一类试样韧性起裂后,经历较长的韧性稳定扩展,仅在锤击区域产生孤立的脆性断裂形貌区;第二类试样韧性起裂后,经历韧性稳定扩展,转变为脆性断裂直至试样破坏,脆性面积较大;第三类试样起裂区和锤击侧均为韧性断裂形貌,仅在试样中部核心部位产生脆性断裂区域。通过降低试样断裂过程中承受的最大载荷和横向约束,可以减少或消除由于试样在试验过程中过大的压缩变形和试样厚度局部增大产生的第一类和第二类异常断口。而主要由于裂尖应力状态发生变化产生的第三类异常断口,其韧脆断裂形貌的转变是材料本身力学性能的体现,在实际管道结构的断裂过程中是会发生的,在试验中也是不可能消除的。因此,不加区别地将异常断口试样全部视为无效试样,人为消除试验中的异常断口,将会存在巨大的安全隐患。
According to different reason caused the brittle area in fracture on DWTT specimen,the appearance of abnormal fracture can be classified into three kinds,the first is isolated brittle fracture area occurred only in the area within hammering,through longer toughness stable enlarging after toughness starting fracture of sample.The second kind of specimen is to transfer to brittle fracture until sample destroyed and the brittle areas become bigger through toughness stable enlarging after toughness starting fracture of sample,the third kind of specimen shows toughness fracture appearance in initial fracture area and the area within hammering,and brittle fracture area only shown in the middle of specimen.The first and second kind of fracture can be reduced and removed,which caused by compression and distortion in test process and thickness of specimen become larger locally though reducing the maximum load and transverse restriction subject to in fracture process with regards to the third fracture,its transition from toughness to brittle depend on mechanical property of material itself,its occurrence accompanies with actual fracture of pipeline and can not be avoided in test.So,it will cause seriously safety problem to consider all specimens with Abnormal fracture as invalid specimen.
出处
《焊管》
2006年第4期25-30,共6页
Welded Pipe and Tube
