Development of high strength and toughness austemper ductile cast iron and application to its structural part materials

高强韧性等温球墨铸铁的研制及其在结构件材料中的应用

• 批准号: 06452336
• 负责人: AOYAMA Masaji
• 金额: $ 3.84万
• 依托单位: DAIDO INSTITUTE OF TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06452336/
• 关键词: DUCTILE CAST IRON; HEAT TREATMENT; AUSTEMPERING; CORROSION RESISTANCE; FATIGUE CRACK PROPAGATION; IMPACT TESTING; Cu-Ni ALLOY (8)

This research aims at the development of atmospheric resistance austemper ductile cast iron which consider use in high strength, toughness, and the corrosion environment and practical use.The following experiment was carried out. The research clarified the best heat treatment conditions by austemper treatment of the Cu-Ni alloyed cast iron. The austemper treatment conditions and the elucidation of the mechanism evaluated strength and the impact characteristic by the instrumented Charpy impact test and the tensile test. Furthermore, the destruction behavior and the fatigue strength evaluation of the cast iron were experimented with the fatigue flaw growth resistance test. The evaluation of corrosion resistance was executed by in the ferric sulfate solutions and the atmospheric exposure examination.As a result of this research, the Ni-Cu alloyed cast iron obtained a remarkable impact characteristic with heat treatment. Strength and toughness reached absorbed energy of 20J by the austempering of 623K.As the crack initiation energy increases, the fracture load reached a high value. Crack propagation advanced gradual after reaching the maximum load value. An excellent high ductility and a high strength material were obtained by austemper treatment. Stress intensity factor (DELTA K) of the austempered cast iron enlarged the crack propagation resistance and showed the growth of a steady crack. Also, threshold stress intensity factor (DELTA Kth) showed a high value with austemper treatment. However, DELTA Kth was not able to be improved with the alloy material.Corrosion resistance of the Cu-Ni alloy cast iron have increased to two times that of non-alloy material in outdoor exposure test and in the ferric sulfate solutions.

本研究的目的是开发考虑在高强度、高韧性和耐腐蚀环境下使用的耐大气奥氏体球墨铸铁。进行了以下实验。研究明确了对铜镍合金铸铁进行奥氏体热处理的最佳热处理条件。通过仪器夏比冲击试验和拉伸试验，对奥氏体处理条件和机理进行了分析，评价了强度和冲击特性。通过抗疲劳裂纹生长试验，对铸铁的破坏行为和疲劳强度进行了试验研究。通过硫酸铁溶液和大气暴露试验对其耐蚀性进行了评价。研究结果表明，Ni-Cu合金铸铁经热处理后具有显著的冲击特性。经623K等温回火，强度和韧性达到20J的吸收能。随着裂纹起裂能的增大，断裂载荷达到较高值。裂纹扩展在达到最大荷载值后逐渐推进。通过奥氏体处理获得了优异的高延展性和高强度材料。等温铸铁的应力强度因子δ K增大了裂纹扩展阻力，裂纹扩展为稳定裂纹。低温处理的阈值应力强度因子（DELTA Kth）也较高。然而，DELTA Kth无法通过合金材料得到改善。铜镍合金铸铁在室外曝晒试验和硫酸铁溶液中的耐蚀性提高到非合金材料的2倍。