مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

بررسی اثر پیشگرم بر روی کاهش تنش‌های پسماند در جوشکاری تعمیری لوله های فولادی

نویسندگان
1 دانشگاه تربیت مدرس، تهران
2 دانشگاه تربیت مدرس
چکیده
در این مقاله به مطالعه اثر حرارت پیشگرم بر جوشکاری تعمیری در لوله‌های فولادی و تحلیل ترمو-الاستیک-پلاستیک این فرآیند به کمک روش المان محدود پرداخته شده است. برای تایید مدل المان محدود از داده‌های تجربی جوشکاری تعمیری لوله فولاد کربنی که با روش کرنش‌سنجی سوراخ بدست آمده بودند استفاده شده است. ارتباط خوبی بین نتایج المان محدود و داده‌های تجربی بدست آمد. نتایج نشان داد روش محاسباتی توسعه یافته در این مطالعه یک روش موثر جهت پیش‌بینی تنش پسماند در جوشکاری تعمیری لوله‌های مورد نظر است. اثر‌‌ پیشگرم بر روی کاهش تنش‌های پسماند جوشکاری در تعمیر لوله‌های فولاد زنگ‌نزن و فولاد کربنی با استفاده از مدل المان محدود تایید شده مورد مطالعه قرار گرفت. مشاهده شد که با افزایش دمای پیشگرم، تنش‌های پسماند محوری کششی هم در سطح داخلی و هم در سطح خارجی لوله فولاد زنگ‌نزن و فولاد کربنی به ترتیب تا 35 و 50 درصد کاهش یافته، ولی تنش‌های فشاری در سطح خارجی تغییر چندانی نکرده است. هم‌چنین در لوله فولاد زنگ‌نزن با افزایش دمای پیشگرم تنش پسماند محیطی کششی در سطح خارجی و در لوله فولاد کربنی تنش محیطی کششی در سطح داخلی کاهش اما تنش‌های فشاری تغییر قابل توجهی نمی‌کنند. بطور کلی پیشگرم بر اندازه و توزیع تنش پسماند محیطی در سطح داخلی لوله فولاد زنگ‌نزن تاثیر مهمی ندارد. هم‌چنین در دماهای پیشگرم بالا تنش-های پسماند محوری توزیع وسیع‌تری خواهند داشت
کلیدواژه‌ها

عنوان مقاله English

Application of pre-heating in the reduction of residual stress in the repair welds of steel pipes

نویسندگان English

mehran Charkhi 1
Davood Akbari 2
1 Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran.
2 Mechanical engineering-tarbiat modares university
چکیده English

In this paper, the study application of pre-heating on the repair welds in the steel pipes and analysis of thermo-elastic-plastic molding of this process was investigated using finite element method. In order to verify the model, experimental data for repair welding of carbon steel pipe, obtained by deep hole drilling method, were utilized. Good agreement was observed between the finite element and experimental data. The results indicated that the developed computational method is an effective tool to predict the residual stress of pipes in the repair welded. The present finite element model was developed in repair welded carbon steel and stainless steel pipes to consider the effect of preheating. It was observed that by increasing the preheating temperature in the repair welded pipes, tensile axial residual stresses on the inner surface and outer surface of the carbon steel and stainless steel pipes decreased 35 and 50 percent respectively, but the compressive axial residual stresses on the outer surface have small variation. Moreover, by increasing the preheating temperature tensile hoop residual stresses on the outer surface on the stainless steel side and tensile hoop residual stresses on the inner surface on the carbon steel side decreased, but only a small variation was observed on the compressive hoop residual stresses. In general, there is no significant effect on the magnitude and distribution of hoop residual stresses on the inner surface of the stainless steel pipe. Also, high preheating temperatures will have wider distribution of axial residual stresses.

کلیدواژه‌ها English

Preheat
Residual stresses
repair welding
FEM analysis
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