بررسی تجربی تنش پسماند در قطعات با مقطع متغیر در فرآیند ذوب انتخابی لیزری

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری، مهندسی مکانیک، دانشگاه تربیت دبیر شهید رجایی، تهران

2 استادیار، مهندسی مکانیک، دانشگاه تربیت دبیر شهید رجایی، تهران

چکیده

یکی از چالش‌های مهم در فرآیند ذوب انتخابی لیزری، ایجاد تنش‌های پسماند در قطعات تولید شده می‌باشد. تنش‌های پسماند می‌تواند روی دقت ابعادی، خواص مکانیکی و عملکرد قطعه اثرات منفی داشته باشد. در اغلب قطعات صنعتی مانند پره­های توربین، مقطع قطعه در طول آن تغیر می­کند که می­تواند در مقدار تنش­های پسماند تأثیرگذار باشد. مهمترین پارامترهای فرآیند ذوب انتخابی لیزری شامل توان لیزر، سرعت اسکن، ضخامت لایه­ها و فاصله هاشور مسیر اسکن می‌باشد. پارامترهای مذکور روی پروفیل حرارتی ایجاد شده در حین فرآیند ساخت موثراند؛ بنابراین می توانند در ایجاد تنش‌های پسماند در قطعات  نقش اساسی داده باشند. در این مقاله با روش تجربی تأثیر پارامتر فاصله هاشور مسیر اسکن روی مقدار تنش پسماند نمونه‌های اینکونل 625 با مقاطع متفاوت در فرآیند ذوب انتخابی لیزری مورد بررسی قرار گرفته است؛ به گونه­ای که چگالی انرژی از محدوده مناسب برای تراکم نمونه­ها خارج نشود. با استفاده از روش تست غیر مخرب پراش اشعه ایکس، تنش پسماند در مرکز سطح نمونه‌ها و فصل مشترک مقاطع نمونه­ها اندازه­گیری شده است. نتایج نشان می‌دهد که با افزایش فاصله هاشور مسیر اسکن، مقدار تنش پسماند کاهش می­یابد. همچنین مقایسه مقدار تنش پسماند در مرکز سطح دو بخش پایینی و بالایی نمونه‌ها نشان می‌‌دهد که مقدار تنش پسماند در فصل مشترک دو سطح مقطع تقریباً به نصف کاهش می‌یابد.

کلیدواژه‌ها


عنوان مقاله [English]

Experimental study of residual stress in parts with variable cross section in selective laser melting process

نویسندگان [English]

  • Morteza Mansouri 1
  • Afshin Kazerooni 2
  • Mohammad Meghdad Fallah 2
1 Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran.
2 Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran.
چکیده [English]

One of the major challenges in the selective laser melting process is the generation of residual stresses in the processed parts. The residual stress can have detrimental effects on the dimensional accuracy, mechanical properties and performance of the part. In most industrial components, such as turbine blades, the cross section of the part changes along its length which can affect  the amount of residual stress. The most important  parameters of selective laser melting process include laser power, scanning speed, layer thickness and hatch spacing. These parameters are effective on the thermal profile created during the manufacturing process. Therefore, they can play an essential role in the formation of residual stresses in parts. In this paper, the effect of hatch spacing parameter on the residual stress magnitude of Inconel 625 samples with different cross sections has been investigated experimentally; so that the energy density does not exceed the appropriate range for the density of the samples. Using the non-destructive X-ray diffraction method, the residual stresses measured in the center of the sample surface and the intersection of the two variable sections of the samples. The results showed that the use of a larger hatch space significantly reduces the amount of residual stress. Also, the comparison of the amount of residual stress in the center of the surface of the lower and upper parts of the samples shows that the amount of residual stress in the interface between the two cross sections is reduced by almost half.

کلیدواژه‌ها [English]

  • Selective Laser Melting Process (SLM)
  • Residual Stress
  • Samples with variable cross section
  • Inconel 625
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