Effect of Pulse Shapes on the Weldability of High Conductivity Copper ‎C101 by Nd-YAG Laser

تم لحام وصلات تراكب مماثلة من صفائح رقيقة من النحاس النقي C101 باستخدام اللحام بالليزر النبضي. تم دراسة تأثير معاملات اللحام بالليزر على الخواص الميكانيكية. أظهرت النتائج التجريبية أنه يمكن الحصول على وصلات خالية من عيوب الصوت من وصلات نحاسية - نحاسية مماثلة حيث يحدث الكسر بعيدًا عن خط اللحام. يقترح العمل الحالي تحسين التحكم في التصميم لثلاثة أشكال مختلفة للنبض؛ مستطيلة (عادية)، منحدرة لأسفل ومعدلة وتستخدم في لحام ست عينات نحاسية مختلفة لتحقيق أقصى قوة شد وقص للمفاصل. أوضحت النتائج أن شكل النبضة المعدلة هو الأمثل في اختبار شد القص. كان لشكل النبضة المنحدرة تأثير أقل أهمية على قوة المفصل النحاسي عند مقارنته بشكل النبضة المستطيلة. تم الحصول على العلاقة بين معلمات الإدخال والإخراج من خلال استخدام برنامج Minitab، وتم استخدام برنامج Matlab للوصول إلى الحل الأمثل. أظهرت الخوارزمية الجينية أن المقدار الأمثل الذي تم تحقيقه لقوة القص كان 77.9 ميجا باسكال، وكانت معلمات الإدخال المثلى هي طاقة النبضة البالغة 39 جول وعرض النبضة 8.5 وتردد 10 هرتز والسرعة الخطية 160 ملم / دقيقة. Similar lap joints of pure copper C101 thin sheets were welded using pulsed laser welding. The effect of laser welding parameters on mechanical properties was investigated. The experimental results revealed that sound defect-free joints could be obtained from similar copper-copper joints where the fracture occurs away from the weld line. The present work proposes improved design control for three different pulse shapes; rectangular (normal), ramped-down and modulated which are used to weld six different copper samples to achieve the optimum tensile-shear strength of the joints. Results showed that modulated pulse shape has the optimum in the shear-tensile test. Ramped-down pulse shape had a less significant effect on the strength of the copper joint when compared with the rectangular pulse shape.  The relationship between the input and output parameters was obtained by employing Minitab software, and the Matlab software was used in order to reach the optimum solution. The genetic algorithm showed that the optimum magnitude achieved for the shear strength was 77.9 MPa, and the optimum input parameters were pulse energy of 39J, the pulse width of 8.5, frequency of 10Hz and linear speed of 160mm/min.&nbsp

Wire Arc Additive Manufacturing of Steel: Deposition Patterns Effect on Microstructure and Mechanical Properties

Recently, Metal Inert Gas (MIG) -based weld deposition process is one of the deposition-based Additive Manufacturing (AM) processes. This technique has created considerable interest due to the advantages it offers of being able to produce fully functional, complex, dense metallic objects. The study mainly aims to investigate the influence of a variety of deposition patterns on the microstructure and the mechanical properties of steel materials built on a low alloy steel substrate by MIG process. Experiments were carried out using a semi-automated MIG welding to built the samples manufactured using five different deposition patterns (longitudinal, transverse, right network, oblique and oblique network). Microscopy generally showed coarse equiaxed grains in the lower regions, fine equiaxed grains in the middle regions and columnar grains in the upper regions. The maximum hardness was (201HV) for the sample built with the oblique pattern, while the minimum hardness was (170 HV) for the sample built longitudinally. The highest average tensile strength value was (480 MPa) for the sample built longitudinally. The fracture mode was significantly ductile.The lowest average tensile strength value was however (262.5 MPa) for the sample built transversely, and the fracture mode was brittle

Brazing Polycrystalline Diamonds (PCDs) in Applications of Cutting Tools: A review

This article surveys all researches which have conducted on polycrystalline diamond (PCDs) cutting tools, with particular consideration to the characteristics and performance of diamond-metal interface. There has been a revolution in industry over the fifty years or so, due to the usage of diamond in numerous applications, because of the special properties of diamond, joining diamonds to various materials by brazing requires much more precision than traditional brazing. Diamond is frequently utilized in cutting tools and workpieces because of its great hardness and wear resistance. Copper base filler & nickel base filler are the two materials that are most frequently used as brazing fillers in diamond brazing. This review describes the properties of diamond, how it interacts with metals and alloys, how it wets them, what influences these interactions, and how practical aspects of diamond joining is. Additionally, an analysis is done on a number of new brazing alloys, including amorphous Ni-based brazing filler metals

Post-migration stress among adult male Iraqi refugees and its implications for counselling and psychotherapy : a qualitative study

This three-phase study explores how counselling and psychotherapy can address the post-migration stress that adult male Iraqi refugees can experience in later stages of exile (defined in this study as having lived in Sweden for a minimum of five years). In Phase 1 the exile-related experiences of ten Iraqi refugee men were explored with specific emphasis on social support, acculturation, racial discrimination, and support systems. In Phase 2 the counselling experiences of ten adult male Iraqi refugee ex-counselling clients were explored. In Phase 3 the views of eight professionals were explored regarding their experiences of counselling Iraqi refugee men. The adult male Iraqi refugee participants in Phase 1 and Phase 2 were individually interviewed using semi-structured interviewing. The twenty interviews were analysed using Interpretative Phenomenological Analysis (IPA). In Phase 3, the findings from Phase 1 and Phase 2 were used to design two focus group interviews using four mental health professionals in each group. The two focus group interviews were also analysed using IPA. The main findings of Phase 1 were that Iraqi refugee men expressed feeling disempowered, racially discriminated against, and marginalised by society. The main findings of Phase 2 were that adult male Iraqi refugee ex-counselling clients expressed a reluctance to disclose to therapists issues pertaining to their ethnic minority status and experienced racial microaggressions from therapists. The main findings of Phase 3 were that professionals described avoiding and struggling with cultural issues. Another main finding of Phase 3 was that in spite of client feedback revolving around the need for practical help and the experience of post-migration stress, professionals emphasised pre-migration trauma in discussing their views on counselling this client group. Based on the findings of this three-phase study, a pluralistic counselling approach is proposed to address the different post-migration stressors that adult male Iraqi refugees can experience in later stages of exile in Sweden and perhaps other Western countries

Wire Arc Additive Manufacturing of Steel: Deposition Patterns Effect on Microstructure and Mechanical Properties

Recently, Metal Inert Gas (MIG) -based weld deposition process is one of the deposition-based Additive Manufacturing (AM) processes. This technique has created considerable interest due to the advantages it offers of being able to produce fully functional, complex, dense metallic objects. The study mainly aims to investigate the influence of a variety of deposition patterns on the microstructure and the mechanical properties of steel materials built on a low alloy steel substrate by MIG process. Experiments were carried out using a semi-automated MIG welding to built the samples manufactured using five different deposition patterns (longitudinal, transverse, right network, oblique and oblique network). Microscopy generally showed coarse equiaxed grains in the lower regions, fine equiaxed grains in the middle regions and columnar grains in the upper regions. The maximum hardness was (201HV) for the sample built with the oblique pattern, while the minimum hardness was (170 HV) for the sample built longitudinally. The highest average tensile strength value was (480 MPa) for the sample built longitudinally. The fracture mode was significantly ductile.The lowest average tensile strength value was however (262.5 MPa) for the sample built transversely, and the fracture mode was brittle

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Brazing Polycrystalline Diamonds (PCDs) in Applications of Cutting Tools: A review

This article surveys all researches which have conducted on polycrystalline diamond (PCDs) cutting tools, with particular consideration to the characteristics and performance of diamond-metal interface. There has been a revolution in industry over the fifty years or so, due to the usage of diamond in numerous applications, because of the special properties of diamond, joining diamonds to various materials by brazing requires much more precision than traditional brazing. Diamond is frequently utilized in cutting tools and workpieces because of its great hardness and wear resistance. Copper base filler & nickel base filler are the two materials that are most frequently used as brazing fillers in diamond brazing. This review describes the properties of diamond, how it interacts with metals and alloys, how it wets them, what influences these interactions, and how practical aspects of diamond joining is. Additionally, an analysis is done on a number of new brazing alloys, including amorphous Ni-based brazing filler metals