تاثیر تخلخل بر خستگی برنز آلومینیوم نیکل دار ریختگی و ارایه روشی برای کاهش پراکندگی داده ها

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشگاه صنعتی اصفهان، دانشکده مهندسی مواد

2 دانشکده مهندسی مواد، دانشگاه صنعتی اصفهان

چکیده

در این پژوهش تاثیر حفرههای ریختگی بر استحکام خستگی برنز آلومینیوم نیکلدار ریختگی مورد مطالعه قرار گرفت. به این منظور آزمایش خستگی چهار نقطهای تحت شرایط R = -1 و فرکانس 50 هرتز روی این آلیاژ انجام شد. بررسی نتایج و رسم منحنی S-N آلیاژ نشان داد به دلیل وجود تخلخل و عیوب ریختگی در نمونه ها، داده های خستگی پراکندگی زیادی دارند که این پراکندگی با افزایش تنش اعمال شده بیشتر می شود. جهت کاهش پراکندگی داده ها و محاسبه استحکام خستگی، اندازه تخلخل در سطح مقطع شکست به کمک تصاویر میکروسکوپی الکترونی روبشی و تکنیک پردازش تصویر اندازه گرفته شد. سپس به کمک نتایج به دست آمده استحکام خستگی بر اساس اندازه سطح موثر نمونه ها محاسبه شد. بررسی نتایج نشان داد که رسم منحنی S - N بر اساس تنش محاسبه شده به عیوب ریخته گری و حفرهها وابستگی کمتری دارد و شاخص واقعی تری از استحکام خستگی برنز آلومینیوم نیکلدار ریختگی به شمار می آید.

کلیدواژه‌ها


عنوان مقاله [English]

Influence of Porosity on Fatigue of Cast Nickel Aluminum Bronze and AProposed Method to Reduce scatter of data

نویسندگان [English]

  • Saghar Fooladi Mahani 1
  • Fakhreddin Ashrafizadeh 1
  • Mohammad Ali Golozar 2
1 Isfahan University of Technology, Materials engineering faculty
2 Materials Engineering, Isfahan University of Technology, Isfahan
چکیده [English]

In this study, the effect of casting porosity on the strength of cast nickel aluminum bronze (NAB) was investigated. For this purpose, four-point fatigue tests were carried out under R = -1 and 50 Hz on this alloy. Experimental results and plotted fatigue curve indicated high values of scattering in fatigue data, increased at applied stress levels higher 150 MPa. To reduce scattering and to obtain a more realistic fatigue strength, pore sizes were measured from the fracture surfaces of the specimens by using image processing technique. The fatigue strength was, then, calculated based on the effective area and fatigue curves were re-plotted. Results indicated that S - N curves obtained by this method are independent from casting defects and could present a better index for fatigue strength of the casting alloy. Therefore, it was concluded that the strength was obtained from this method could be an appropriate reference value when considering the fatigue properties of cast nickel aluminum bronze.

کلیدواژه‌ها [English]

  • “nickel aluminum bronze”
  • “casting structure”
  • “porosity”
  • “fatigue”
  • “S-N curve”
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