Establishing Strength Evaluation Method of Very Thin Ductile Cast Iron and the Way of Improving Reliability of Thin Wall Castings.

建立极薄球墨铸铁强度评价方法及提高薄壁铸件可靠性的途径。

• 批准号: 18560708
• 负责人: NOGUCHI Toru
• 金额: $ 2.47万
• 依托单位: Hokkaido University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18560708/
• 关键词: Casting; Ductile cast iron; Thin wall; Strength evaluation; Tensile strength; Elongation; Toughness; Nondestructive evaluation; 引張強さ; 破壊靱性; SP試験; 引張試験

The purpose of this research is to establish the way of strength evaluation of very thin (less than 2 mm) ductile cast iron by small test pieces and to find the way to improve reliability of thin wall castings. Tensile properties, toughness, fatigue properties and nondestructive evaluation were discussed.1) Tensile test: A small test piece 4.5 mm wide and 2 mm thick with 12 mm gauge length was proposed, with which, tensile strength and elongation equivalent to the ones from a 14 mm diameter standard test piece are obtained. Elongation should be determined from the load-elongation curve measured.2) Toughness test: Small punch test (SP test) by 10×10×0.5 (mm) test piece was applied. Crack initiation deflection δ^* is determined by the measured load deflection curve, and equivalent fracture strain ε_<qf> is estimated, from which, fracture toughness J_<Ic> is determined. J_<Ic> can be also estimated from HRB hardness.3) Fatigue test: It was concluded that fatigue tests with stress ratio, R= -1.0, by thin plate test pieces should be carried. Special jigs for the test were developed. Fatigue crack initiation from the cast surface and the process of primary and steady crack propagation will be observed. Casting method to get sound thin plate specimens with ordinary melt treatment was also developed.4) Nondestructive evaluation: Eddy current test was applied to estimate the hardness and the microstructure. Improving the measurement accuracy and new standards different from the thick specimens may enable the estimation.

本研究的目的是建立用小试件评定特薄（小于2 mm）球墨铸铁强度的方法，并寻求提高薄壁铸件可靠性的途径。1）拉伸试验：提出了一种宽度为4.5mm、厚度为2 mm、标距为12 mm的小试样，其抗拉强度和伸长率与直径为14 mm的标准试样相当。延伸率应根据测量的载荷-延伸率曲线确定。2）韧性测试：采用10×10×0.5（mm）试件进行小冲杆测试（SP测试）。由实测载荷-挠度曲线确定裂纹萌生挠度δ^*，估算等效断裂应变ε<qf>，由此确定断裂韧度J<Ic>。J_<Ic>也可以由HRB硬度估算。3）疲劳试验：得出应进行薄板试件应力比R=-1.0的疲劳试验的结论。开发了用于测试的专用夹具。观察了疲劳裂纹从铸件表面萌生的过程以及初始裂纹稳定扩展的过程。4）无损检测：采用涡流检测技术检测合金的硬度和显微组织。提高测量精度和新的标准不同的厚标本可能使估计。

项目成果

Evaluation Method of Fatigue Characteristics of Thin Wall Ductile Cast Iron

薄壁球墨铸铁疲劳特性评价方法

• 发表时间: 2007
• 作者: SAMESHIMA Daigo;HORIKAWA Noritaka;NAKAMURA Takashi
• 通讯作者: NAKAMURA Takashi

Toughness Evaluation of Thin Wall Ductile Cast Iron by SP Test

SP试验评价薄壁球墨铸铁的韧性

• 发表时间: 2007
• 作者: Daigo Sameshima;TNoguchi;et. al.
• 通讯作者: et. al.

Fatigue Characteristics of Ductile Cast Iron Including Small Chill Structure

含小冷硬组织的球墨铸铁的疲劳特性

• 发表时间: 2007
• 作者: SAMESHIMA Daigo;ENDO Takeshi;NOGUCHI Toru;HORIKAWA Noritaka;NAKAMURA Takashi
• 通讯作者: NAKAMURA Takashi

スモールパンチ試験を用いた薄肉球状黒鉛鋳鉄のじん性評価

小冲头试验评价薄壁球墨铸铁的韧性

• 发表时间: 2008
• 期刊: 鋳造工学 80
• 作者: 鮫島大湖;野口徹;他
• 通讯作者: 他

SP試験を用いた薄肉球状黒鉛鋳鉄のじん性評価

SP试验评价薄壁球墨铸铁的韧性

• 发表时间: 2006
• 期刊: 日本鋳造工学会第148回全国講演大会 講演概要集 148
• 作者: 鮫島大湖;野口徹;中村孝;桃野正
• 通讯作者: 桃野正