A Study on the Micro-mechanisms for the Crack Initiation and Growth Ductile Fracture.

裂纹萌生和扩展延性断裂的微观机制研究。

• 批准号: 15360458
• 负责人: KANEDA Shigehiro
• 金额: $ 6.91万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15360458/
• 关键词: ductile fracture; stress triaxiality; SM490B; prestrain; AE; dimple; cleavage; 脆性破壊; 予ひずみ; 応力三軸度; 相当塑性ひずみ; 柱・梁部材; 予歪み; 結晶方位; 粒界; 相当塑性歪み

Relations between equivalent plastic strain and stress triaxiality were studied by fracture tests of round notched bar tensile specimens. The critical ductility curves represented by above-described relationship were constructed by fracture test results and FEM analyses.Base material used in the tests is as received SM490B steel. The yield and ultimate strength at room temperature were 353 and 543 MPa respectively. Compressive prestrain up to 30% plastic strain was given in some specimens. The effects of prestrain and notch radius on ductile fracture initiation behavior were investigated and observed the fractured surface by scanning electron microscope (SEM).Damage initiation behavior during the tests was detected by use of AE sensors attached to the specimens. It is shown that prestrain leads to cleavage micro-cracking and reduces ductility. From SEM-fractographs, it is found that fractured surface is 100% dimple in as-received material, in the meantime, tiny amounts of cleavage in 10% prestrain material, up to 100% cleavage in 30% prestrain material, respectively.

通过圆形凹口抗拉伸标本的断裂测试研究了等效塑性应变与应力三轴性之间的关系。由骨折测试结果和FEM分析构建了由上述关系表示的临界延展性曲线。测试中使用的基本材料是接收的SM490B钢。室温下的产量和最终强度分别为353 MPa。在某些标本中给出了高达30％塑性应变的压缩率。研究了Prestrain和Notch Radius对延性断裂起始行为的影响，并通过扫描电子显微镜（SEM）观察到断裂的表面。通过使用附着在标本上的AE传感器检测到测试过程中损伤起始行为。结果表明，prestrain会导致切割微裂缝并降低延展性。从Sem-Fractographs中可以发现，骨折的表面在接收的材料中是100％的凹痕，同时，在10％的prestrain材料中少量裂解，分别在30％的prestrain材料中分别裂解高达100％的裂解。

项目成果

鋼材の延性破壊発生挙動に及ぼす予ひずみの影響

预应变对钢材延性断裂起裂行为的影响

• 发表时间: 2005
• 期刊: 材料 第54巻
• 作者: 吉成仁志;榎並啓太郎;菅 満春;金田重裕
• 通讯作者: 金田重裕

The Effect of Prestrain on ductile Fracture Initiation of Steel

预应变对钢延性断裂萌生的影响

• 发表时间: 2005
• 期刊: Journal of Materials Science JAPAN Vol.54, No3
• 作者: Hitoshi Yoshinari;Keitaro Enami;Mitsuharu Kan;Shigehiro Kaneda
• 通讯作者: Shigehiro Kaneda