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Article
Study the Effect of Welding Parameters on the Residual Stresses Induced by Submerged Arc Welding process

Authors: Samir Ali Amin --- Sadeq Hussein Bakhy --- Fouad Ali Abdullah
Journal: AL-NAHRAIN JOURNAL FOR ENGINEERING SCIENCES مجلة النهرين للعلوم الهندسية ISSN: 25219154 / eISSN 25219162 Year: 2017 Volume: 20 Issue: 4 Pages: 945-951
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

Welding residual stress has influences on fatigue, fracture, and corrosion. It is therefore important to explore the welding factors effect on the residual stresses. In this work, four welding factors (current, arc voltage, welding travel speed and included angle) were used to weld low carbon steel (ASTM A516 Grade 60).The experiments included welding of (60) pieces with dimensions of (300 x 150) mm and 10 mm thickness that were conducted based on the design matrix founded by using design of experiment (DOE) software (DESIGN EXPERT 10) with response surface methodology (RSM) technique. The X-Ray diffraction (XRD) method was used to measure the residual stress, which was then modeled and optimized in terms of the welding factors using (RSM) technique. The data showed that the welding travel speed and arc voltage have a significant influence on the residual stress. It was found that the optimum solution for minimum residual stress was at 450 Amp welding current, 34 volt arc voltage, 38 cpm welding speed, and 60⁰ included angle. Where, the optimum value of residual stress was (-88.4 MPa). Finally, the predicted and experimental results of residual stress were in agreement with a maximum error of 1.8%.

تؤثر الأجهادات المتبقية المتولدة من عملية اللحام على كل من الكلل والتآكل والكسر الميكانيكي. لذلك فمن المهم دراسة تأثير عوامل اللحام على تولد الاجهادات المتبقية. في هذه الدراسة تم تم دراسة حالة الاجهادات المتبقية المتولدة من اللحام بطريقة القوس المغمور لصلب واطيء الكاربون نوع (A516 Gr 60), حيث تم استخدام اربعة عوامل لحام هي التيار والفولطية وسرعة اللحام وزاوية اخدود اللحام, ان ابعاد القطع المعدنية المعدة للحام هي (300x150x10 mm). تم بعد ذلك قياس الاجهادات المتبقية المتولدة بطريقة حيود الاشعة السينية (XRD) ثم عمل موديل رياضي وحساب القيمة المثلى بوصفها دالة لعوامل اللحام المستخدمة بواسطة تقنية تصميم التجارب (DOE) مع منهجية الاستجابة السطحية (RSM). حيث اظهرت النتائج ان التأثير الاكبر على تولد الاجهادات المتبقية كان لفولطية القوس وسرعة اللحام, كذلك وجد ان الظروف المثلى التي تعطي اقل اجهادات متبقية هي (450 Amperes, 34 Volt, 38 cpm and 60⁰ Included Angle) حيث تكون القيمة المثلى للاجهادات المتبقية عند هذه الظروف هي (-88.4). واخيراً كان هنالك توافق كبير بين النتائج المتوقعة والعملية للاجهادات المتبقية مع نسبة خطاء قليلة جداً لا تتجاوز 1.8%.

Keywords

: SAW --- Residual Stress --- Welding parameters --- DOE --- RSM


Article
Influence of SAW Welding Parameters on Microhardness of Steel A516-Gr60

Authors: Sadeq H. Bakhy --- Samir A. Amin --- Fouad A. Abdullah
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 10 Part (A) Engineering Pages: 1039-1047
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Submerged Arc Welding (SAW) process is generally used for industries, such as petroleum storage tanks, pressure vessels, and structural components.Good mechanical properties of welded joint lead to crack-free strong joints. In this research, included angle, current, welding travel speed and arc voltage were utilized as welding parameters to weld ASTM A516 Grade 60 (low carbon steel). The experiments were carried out according to a design matrix that established by DOE (Version10) with RSM technique. Microhardness of welded samples was measured by a Digital Microhardness Tester, and then RSM technique was used to model and optimize the microhardness based on the welding parameters. The results showed that the including angle and welding current have a great effect on the microhardness. The optimum solution for minimum microhardness was found at 450 Amp welding current, 38 cpm welding speed, 34-volt arc voltage and included angle of 60⁰. The optimum value of microhardness was (186.7 HV). Eventually, the experimental and predicted results of microhardness were found in good agreement with 4.6%. maximum error.

Keywords

SAW --- Microhardness --- Welding parameters --- DOE --- RSM


Article
EXPERIMENTAL ANALYSIS OF RESISTANCE SPOT WELDING PARAMETERS FOR LOW CARBON STEEL SHEET

Author: Kamal Abdulkareem Mohammed
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 3 Pages: 14-22
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Resistance Spot Welding (RSW) is one of the most efficient fusion welding processes which known as a thermo – electric process used in joining metal by a combination of adjustable parameters (heat, pressure and time), it is high speed, flexible and highly productive process. It is extensively used for many industrial purposes in particular in the automotive industry. The aim of the present work is to study the effect of welding nugget area on the tensile strength of the resistance spot welded joints, the present discussion deals with effect of the parameters of resistance spot welding process (current, time, electrode force) on nugget formation and on failure load of the spot weld joints (the relation between nugget size and strength with input parameters). The test material of the specimens which used in this study is low carbon steel. The mechanical performance (peak load, failure mode) of the welded joints was determined by tensile testing, the testing results were analyzed which were obvious the effectiveness and the necessaries of the suitable or proper welding parameters for the strength of the spot weld joints.


Article
Investigation Parameters of Resistance Spot Welding For AA1050 Aluminum Alloy Sheets
أستقصاء متغيرات لحام مقاومة النقطة لصفائح سبيكة الالمنيوم AA1050

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Abstract

The parameters of resistance spot welding (RSW) performed on low strength commercial aluminum sheets are investigated experimentally, the performance requirements and weldability issues were driven the choice of a specific aluminum alloy that was AA1050. RSW aluminum alloys has a major problem of inconsistent quality from weld to weld comparing with welding steel alloys sheet, due to the higher thermal conductivity, higher thermal expansion, narrow plastic temperature range, and lower electrical resistivity. Much effort has been devoted to the study of describing the relation between the parameters of the process (welding current, welding time, and electrode force) and weld strength. Shear-tensile strength tests were performed to indicate the weld quality. A weld lobe diagrams were constructed to evaluate the weldability of three sheet thicknesses of this alloy. Most appropriate welding time and electrode force are 5 cycles and 1.75-2.25 kN respectively. The ranges of the weldability are 14-28, 18-30, and 22-32 kA for 0.6, 1.0, and 1.5 mm sheet thicknesses respectively. A statistical regression analysis was used to demonstrate the relationship of the process parameters and the strength of the weldments. Two empirical equations for each thickness were proposed to estimate the shear tensile strength of the weldments, one for quadratic and the other linear relationship between the process parameters and the strength. There are no significant differences between the equations when applied to the available data.

تم التحري عملياً عن مًتغيرات لحام المقاومة النقطي على الصفائح المصنوعة من الالمنيوم التجاري واطئ القوة، ولمتطلبات الأداء وقابلية اللحام وجودته اختيرت سبيكة الالمنيوم AA1050. للحام المقاومة النقطي لسبائك الالمنيوم مشكلة كبيرة في استقرارية جودة اللحام من لحام ولحام آخر مقارنة بلحام صفائح سبائك الفولاذ، وذلك للموصلية الحرارية والتمدد الحراري العاليين، قصر المدى الحراري اللدن، والمقاومة الكهربائية المنخفضة لسبائك لالمنيوم عن سبائك الفولاذ. كُرس الكثير من الجهد لدراسة العلاقة بين متغيرات عملية اللحام ( تيار اللحام، زمن اللحام، وقوة ضغط الاقطاب) مع قوة الملحومات. أُجريت فحوصات القوة (قص شد) لبيان جودة اللحام. شكلت مخططات متغيرات اللحام Lobe Diagram لتقييم قابلية اللحام ولثلاثة مقاطع من صفائح سبيكة الالمنيوم المذكورة. أفضل حالة لزمن اللحام هي 5 دورات وقوة ضغط الاقطاب هي 1.75 ــ 2.25 كيلو نيوتن. مدى قابلية اللحام هي 14- 28 ، 18- 30 ، و 22 - 32 كيلو أمبير للصفائح 0.6 ، 1.0 ، و 1.5 ملم على التوالي. تم استخدام تحليل الانحدار الاحصائي لتوضيح العلاقة بين متغيرات عملية اللحام ومتانة قوة الملحومات. تم اقتراح اثنين من المعادلات التجريبية لكل سمك لتخمين متانة قوة اللحام العلاقة الاولى من الدرجة الثانية والاخرى علاقة خطية بين متغيرات عملية اللحام ومتانة قوة الملحومات. وظهر عدم وجود فروقات جوهرية بين العلاقة الخطية والدرجة الثانية عند تطبيقها على البيانات المتاحة.

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