Fatigue strength of in situ processed Cu-Nb composite wires

原位加工Cu-Nb复合丝的疲劳强度

• 批准号: 13650072
• 负责人: KATAGIRI Kazumune
• 金额: $ 2.24万
• 依托单位: IWATE UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650072/
• 关键词: Cu-Nb composite wires; Fatigue strength; Fracture mechanisms; Stress-strain characteristics; Cryogenic temperature; Drawing strain; Nb weight fraction; Electric resistivity; 銅・ニオブ複合線材; 疲労きれつ; ニオブ体積分率; 破面観察; 微視組織; きれつ発生; きれつ進展

In order to investigate the fatigue strength of multi- and mono-strand in-situ Cu-Nb composite wires, fatigue tests at room and cryogenic temperatures and fractographic observations were carried out.1. The 0.2% proof stress and the UTS increased with the Nb content and drawing strain. The Young's modulus did not change with the drawing strain, while it decreased with the Nb content. With decrease in the temperature to 77K, the 0.2% proof stress and the UTS increased by 5 to 10%, while the Young's modulus was almost constant.2. Although the fatigue strength at high stress amplitude region was high in the wire with high drawing strain, it was almost the same in low stress region regardless of the drawing strain. A drastic decrease in the plastic strain range in the initial stage was observed in the fatigue. At 77K, the fatigue strength increased by a factor of 2.The fatigue strength in the wire with high Nb content was high at high stress region, while it was rather low at low sterss region. This is explained by the magnitude of plastic strain range associated with the Young's modulus and work hardening in the wires with high and low Nb content in the high and low stress regions.4. The slip plane decohesion facets and inclusions within the Cu wire sheath were possible sites for the crack initiation. Te magnitude of small irregularity in the fatigue crack propagation region was smaller at low temperature.5. Evidence on the roles of the Nb filaments acting as barriers against crack propagation was obtained.6. The effect of mean stress on the fatigue strength was small.7. The residual resistivity at 4.2K and 14T was 0.10μΩcm and it increased by 0.02μΩ cm with straining by 1.8%.

为了研究多股和单股原位Cu-Nb复合丝的疲劳强度，进行了室温和低温疲劳试验以及断口观察。 1． Nb含量和拉拔应变。杨氏模量不随拉拔应变而变化，但随Nb含量的降低而降低，0.2%屈服强度和UTS增加。 5～10%，而杨氏模量几乎恒定。2．高拉拔应变线材的高应力振幅区域的疲劳强度较高，但无论拉拔应变A如何，在低应力区域疲劳强度几乎相同。在疲劳温度77K时，初始阶段的塑性应变范围急剧减小，疲劳强度增加了2倍。高Nb含量的线材在高应力区域的疲劳强度较高。相当低的低这是通过高应力和低应力区域中与杨氏模量和加工硬化相关的塑性应变范围来解释的。4．钢丝护套是裂纹萌生的可能部位。在低温下，疲劳裂纹扩展区域的小不规则性较小。5． 6．平均应力对疲劳强度影响较小。7．4.2K、14T时残余电阻率为0.10μΩcm，应变增加1.8%。

项目成果

片桐一宗, 佐々木君幸, 伊藤巧, 笠場孝一, 正路良孝, 斎藤隆, 後藤謙次, 富士広: "in situ法Cu-Nb多芯線材の室温における疲労強度"低温工学. 38・4(印刷中). 7 (2003)

Kazumune Katagiri、Kimiyuki Sasaki、Takumi Ito、Koichi Kasaba、Yoshitaka Masami、Takashi Saito、Kenji Goto、Hiroshi Fuji：“原位 Cu-Nb 多芯线的室温疲劳强度” 38・4（出版中）。 7 (2003)

片桐一宗, 伊藤巧, 笠場孝一, 正路良孝, 斎藤隆, 後藤謙次, 富士広: "in situ 法Cu-Nb多芯線材の疲労強度"第26回疲労シンポジウム講演論文集. 73-76 (2002)

Kazumune Katagiri、Takumi Ito、Koichi Kasaba、Yoshitaka Masami、Takashi Saito、Kenji Goto、Hiroshi Fuji：“原位 Cu-Nb 多芯线的疲劳强度”第 26 届疲劳研讨会论文集（2002 年）。

片桐一宗, 佐藤正, 笠場孝一, 正路良孝, 佐々木君幸, 斎藤隆, 後藤謙次, 富士広: "in situ法複合Cu-Nb多芯線材の疲労強度"第79回日本材料学会フラクトグラフィ部門委員会 資料. No.432. 10 (2001)

Kazumune Katagiri、Tadashi Sato、Koichi Kasaba、Yoshitaka Masami、Kimiyuki Sasaki、Takashi Saito、Kenji Goto、Hiroshi Fuji：“原位复合 Cu-Nb 多芯线材的疲劳强度”第 79 届日本材料学会断口学部委员会材料 No. .432.10（2001）