Fracture Mechanics- and Image Processing-Aided Assessment of Fatigue and Fracture Toughness of Austempered Ductile Cast Iron

断裂力学和图像处理辅助评估等温淬火球墨铸铁的疲劳和断裂韧性

• 批准号: 01550060
• 负责人: HARADA Shoji
• 金额: $ 1.41万
• 依托单位: Department of Mechanical Engineering, Faculty of Engineering, Kyushu Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1990
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550060/
• 关键词: Ductile Cast Iron; Low-Cycle Fatigue; Spheroidal Graphite and Matrix; Laser Interferometric Gauge; Crack Initiation and Propagation; Fracture Mechanics; Crack Closure; Bainite, Ferrite and Pearlite Matrix; き裂開口変位

To examine quantitatively the effects of spheroidal graphite and matrix on strength of ductile cast iron, low-cycle fatigue tests were mainly conducted. Three kinds of ductile cast irons, ferritic, pearlitic and bainitic ductile irons with same chemical composition were prepared by heat treatment. First, graphite morphology such as nodule count, nodularity, area fraction etc. of each material was measured by an image processing analyzer. Then, a laser interometric measuring instrument for measuring closure behavior of a spheroidal graphite-initiated small crack with a higher accuracy was newly developed.Through the fatigue tests, it was found that the matrix structure primarily controls the fatigue strength and that the spheroidal graphite plays an important role during the fatigue process from microcrack initiation to final failure. In cases of bainitic and pearlitic materials, a microshrinkage formed during fabrication in the matrix was found to be responsible for the crack initiation site. Finally, the results of macroscopic crack propagation tests revealed that the matrix structure hardly influences the macroscopic crack propagation rate.

为了定量考察球墨和基体对球墨铸铁强度的影响，主要进行了低周疲劳试验。采用热处理工艺制备了化学成分相同的铁素体、珠光体和贝氏体球铁三种球墨铸铁。首先，用图像处理分析仪测量了每种材料的结节数、球化率、面积分数等石墨形态。在此基础上，研制了高精度的球状石墨萌生小裂纹闭合行为激光干涉测量仪，通过疲劳试验发现，基体组织主要控制疲劳强度，球状石墨在微裂纹萌生到最终失效的疲劳过程中起着重要作用。在贝氏体和珠光体材料的情况下，在制造过程中在基质中形成的微收缩被发现是导致裂纹萌生的原因。最后，宏观裂纹扩展试验结果表明，基体结构对宏观裂纹扩展速率几乎没有影响。

项目成果

原田昭治,秋庭義明,植田隆浩,矢野満: "球状黒鉛鋳鉄の低サイクル疲労および機構に及ぼす基地組織の影響" 破壊と新技術シンポジウム(日本機械学会).

Shoji Harada、Yoshiaki Akiba、Takahiro Ueda、Mitsuru Yano：“基础结构对球墨铸铁低周疲劳的影响及机理”断裂与新技术研讨会（日本机械工程学会）。

Shoji Harada・Yoshiaki Akiniwa Takahiro Ueda・Mitsuru Yano: "LowーCycle Fatigue of a Pearlitic Ductile Cast Iron" Proc.4thInt.Conf.Fatigue&Fatigue holds,Fatigue 90.Honolulu. 3. 1649-1654 (1990)

Shoji Harada、Yoshiaki Akiniwa Takahiro Ueda、Mitsuru Yano：“珠光体球墨铸铁的低周疲劳”Proc.4thInt.Conf.Fatigue&Fatigue 举行，Fatigue 90.Honolulu (1990)。

原田 昭治・秋庭 義明・植田 隆浩・矢野 満: "地状黒鉛鋳鉄の低サイクル疲労" 機械学会「破壊と新技術シンポジウム」講演論文集. 47-51 (1990)

Shoji Harada、Yoshiaki Akiba、Takahiro Ueda、Mitsuru Yano：“地质石墨铸铁的低周疲劳”日本机械工程学会“断裂与新技术研讨会”论文集47-51（1990）。

原田 昭治・秋庭 義明・福島 良博: "半導体レ-ザ干渉変位計による微小き裂の開閉口挙動の測定" 日本材料学会第39期学術講演会前刷. 19-21 (1990)

Shoji Harada、Yoshiaki Akiba、Yoshihiro Fukushima：“使用半导体激光干涉位移计测量微裂纹的打开和关闭行为”，日本材料科学学会第 39 届学术会议预印本（1990 年）。

原田 昭治・秋庭 義明・植田 隆浩・矢野 満: "球状黒鉛鋳鉄の低サイクル疲労強度に及ぼす黒鉛粒数の影響" (機械学会講演予定).

Shoji Harada、Yoshiaki Akiba、Takahiro Ueda、Mitsuru Yano：“石墨晶粒数量对球墨铸铁低周疲劳强度的影响”（日本机械工程学会预定演讲）。