Relationship between heat treatment and fatigue crack extension properties demonstrated on the dental alloy casting used as the compact-type specimen

在用作致密型样品的牙科合金铸件上展示了热处理与疲劳裂纹扩展性能之间的关系

• 批准号: 10671820
• 负责人: NAKAMURA Hideo
• 金额: $ 2.05万
• 依托单位: Tokyo Medical and Dental University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10671820/
• 关键词: fatigue crack development; dental alloy; casting; compact-type specimen; heat treatment

Outline of our research performance<<Research object>>In an object to determine causes of the fact that fatigue strength demonstrated no alterations owing to heat treatment, any relationship between extension speed of fatigue crack and stress intensity factor as well as effective stress intensity factor range was researched depending on the heat treatment process.<<Materials and methods>>1. A casting pattern was produced from an acrylic plate, placed in the center of a casting ring, and invested conventionally with a gypsum-bonded investment material. The investment was, after setting, heated for 30 minutes at 100°C and for one hour at 300°C and then maintained for 30 minutes at 700°C. Then it was cast and allowed to cool down to the room temperature prior to devesting. The casting was cleaned with a surface cleaning agent in a ultrasonic cleaner for removing the oxidized layer and the compact test specimen was finally finished from this casting in accordance with ASTM-E647 specificati … More on by the wire electro-discharge machining. A heat treatment was conducted on the specimen as indicated by the alloy manufacturer.2. The crack extension length was measured from the cracks on the fractured part by 100 times power of magnification with the CCD video camera (VS-60, Mitsubishi Chemical).3. Stress intensity factor was calculated in accordance with ASTM-E647 specification. And effective stress intensity factor range was determined through the load division elasticity compliance method. With this method, the load magnitude of the crack opening was to be established by using the substraction circuit of the strain signal and the load bearing signal from the foil strain gauge (FLK-217-1L, Tokyo Sokki Laboratory) which was attached to the rear surface of the sample.4. Fatigue tests were conducted on a hydraulic servo dynamic testing machine manufactured by Instron (8501, Instron) for loading failure stresses repeatedly under the room temperature atmosphere with repeated sign wave as the load waveforms at frequency of 5 Hz, maximum loading of 50〜77.4 kgf, and stress ratio of 0.1.<<Results and Discussion>>The cracks extended throughout the center of the specimen although slight irregularities exhibited. The crack extension speed was approximately 3 X 10ィイD17ィエD1 m/cycle at the effective extension intensity factor range of 15 MPamィイD11/2ィエD1 near around the fractured area, and no significant difference owing to heat treatment was observed. Probable reasons for above results are considered as follows :1. Variation was found to be significant in consequence of using the cast specimen.2. initial crack extension was not established in consequence of greater load magnitude of fracture stress.Future testing will be scheduled by increasing numbers of test specimens.(This research was reported at the 34th Congress Meeting of the Japanese Society for Dental Materials and Devices.) Less

研究成果概要<<研究对象>>以查明疲劳强度未因热处理而发生变化的原因为目的，根据热处理工艺，对疲劳裂纹的扩展速度与应力强度因子以及有效应力强度因子范围之间的关系进行了研究。<<材料与方法>>1.铸造模型由丙烯酸板制成，放置在铸造环的中心，并按常规方式用石膏粘合的包埋材料进行包埋。凝固后，将包埋件在100℃下加热30分钟，在300℃下加热1小时，然后在700℃下保持30分钟。然后将其铸造并在脱模前冷却至室温。在超声波清洗机中使用表面清洗剂对铸件进行清洗，以去除氧化层，最后根据 ASTM-E647 规范，通过线切割放电加工从该铸件中制成致密的测试样本。按照合金制造商的指示对样品进行热处理。2．使用CCD摄像机(VS-60，三菱化学)，以100倍的放大倍率，从断裂部分的裂纹处测量裂纹扩展长度。 3．应力强度因子根据ASTM-E647规范计算。并通过荷载划分弹性柔量法确定有效应力强度因子范围。采用这种方法，通过使用应变信号和来自贴在样品背面的箔应变计（FLK-217-1L，东京测器实验室）的承载信号的减法电路来确定裂纹张开的载荷大小。 4．疲劳试验是在英斯特朗（Instron）制造的液压伺服动态试验机（8501，Instron）上进行的，在室温气氛下以重复正弦波作为载荷波形，频率为5 Hz，最大载荷为50〜77.4 kgf，应力比为0.1。<<结果与讨论>>尽管表现出轻微的不规则性，但裂纹扩展至整个样品中心。在断裂区域附近的有效延伸强度因子范围15MPaィイD11/2ィエD1处，裂纹扩展速度约为3×10ィイD17ィエD1 m/cycle，并且没有观察到由于热处理而产生的显着差异。造成上述结果的可能原因如下： 1．发现使用铸件样本的结果存在显着的变化。2．由于断裂应力的负载幅度较大，未确定初始裂纹扩展。未来的测试将通过增加测试样本的数量来安排。（该研究报告于第 34 届日本牙科材料与设备学会代表大会上。） 少

项目成果

中村英雄ほか: "金銀パラジウム合金の疲労亀裂進展速度に及ぼす熱処理の影響"歯科材料・器械 第34回日本歯科理工学会学術講演会口演集. 18・S34. 206 (1999)

Hideo Nakamura 等：“热处理对金银钯合金疲劳裂纹扩展速度的影响”第 34 届日本牙科科学与工程学会学术会议牙科材料和仪器论文集 18・S34。 (1999)

Hideo, Nakamura et al.: "Effect of Heat Treatment on fatigue crack propagation of Au-Ag-Pd alloy"J J Dent Mat. 18(s34). 206 (1999)

Hideo, Nakamura 等人：“热处理对 Au-Ag-Pd 合金疲劳裂纹扩展的影响”J J Dent Mat。

中村英雄 ほか: "金銀パラジウム合金の疲労亀裂進展速度に及ぼす熱処理の影響"歯科材料・機械 第34回日本歯科理工学会学術講演会口演集. 18・S34. 206 (1999)

Hideo Nakamura 等：“热处理对金银钯合金疲劳裂纹扩展速度的影响”第 34 届日本牙科科学与工程学会学术会议牙科材料和机械论文集 18・S34。 (1999)