دنیای جوشکاری

دنیای جوشکاری

دنیایی از مطالب جوشکاری و بازرسی فنی
دنیای جوشکاری

دنیای جوشکاری

دنیایی از مطالب جوشکاری و بازرسی فنی

ارزیابی عمق ترک با استفاده از تکنیک های جریان گردابی

Evaluation of crack depth using eddy current techniques

with GMR-based probes

ارزیابی عمق ترک با استفاده از تکنیک های جریان گردابی با پروب ها بر پایه - GMR

ABSTRACT

This paper presents experimental and simulated results obtained using the eddy current nondestructive method to conclude about the depth of linear cracks machined on an aluminum plate. Experimental tests were performed with a sinusoidal excitation field of fixed-amplitude and with a giant magnetoresistance-based sensor to measure the resultant magnetic field on the plate surface. To validate and better insight the experimental results, numerical simulations have been carried out with a commercial program for conditions similar to the experimental case studies. A scheme to infer about crack depth is proposed.

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فرآیند شکل دهی ادغام شده با لحیم کاری القایی Induction Brazing

Forming Process Integrated Induction Brazing 

فرآیند شکل دهی ادغام شده با لحیم کاری القایی

ABSTRACT

Processing steps additional to forming operations, such as joining, usually require a vast effort for transport and storage. Due to integration of currently external production steps, processes could be synchronized. Brazing represents an additional operation, which is likely to gain of importance in the light of an increasing relevance of light weight construction. Servo presses enable an adjustment of the ram motion to process requirements. Hence, the ram motion can be adjusted to create a time slot for the execution of additional processes inside the press. In this paper, the possibility to integrate brazing into forming process chains is investigated.  For a demonstration part, a tool that allows brazing inside a servo press is developed. Achievable part qualities and cycle times are  evaluated. 


 

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رفتار خستگی خوردگی آلیاژ آلومینیوم جوشکاری شده

Corrosion fatigue behaviour of aluminium alloy 6061-T651 welded

using fully automatic GMAW and ER5183 filler alloy

رفتار خستگی خوردگی آلیاژ آلومینیوم 6061-T651 جوش داده شده با (GMAW)

با آلیاژ ER5183 به عنوان فیلر

ABSTRACT

The fatigue life of aluminium 6061-T651 at various applied stress amplitudes in the unwelded and welded condition was found to be significantly reduced on immersion in a 3.5% NaCl simulated sea water solution, compared to that measured in ambient air. The ratio of fatigue life in NaCl test solution to that in air increased as the stress amplitude decreased. The observed reduction in the fatigue life in the NaCl test solution was most likely due to the presence of pits which nucleated on second phase particles or precipitates. Welded joints performed using pulsed gas metal arc welding and ER5183 filler wire failed at the interface between the weld metal and the heat-affected zone as a result of a high pitting rate in this region.


  

ادامه مطلب ...

رفتار خستگی خوردگی آلیاژ آلومینیوم جوشکاری شده

Corrosion fatigue behaviour of aluminium alloy 6061-T651 welded

using fully automatic GMAW and ER5183 filler alloy

رفتار خستگی خوردگی آلیاژ آلومینیوم 6061-T651 جوش داده شده با (GMAW)

با آلیاژ ER5183 به عنوان فیلر

ABSTRACT

The fatigue life of aluminium 6061-T651 at various applied stress amplitudes in the unwelded and welded condition was found to be significantly reduced on immersion in a 3.5% NaCl simulated sea water solution, compared to that measured in ambient air. The ratio of fatigue life in NaCl test solution to that in air increased as the stress amplitude decreased. The observed reduction in the fatigue life in the NaCl test solution was most likely due to the presence of pits which nucleated on second phase particles or precipitates. Welded joints performed using pulsed gas metal arc welding and ER5183 filler wire failed at the interface between the weld metal and the heat-affected zone as a result of a high pitting rate in this region.


  

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شکست خستگی در اتصال جوش داده شده آلیاژ آلومینیوم

Features of AcousticEmission Signals during the Initiation 

of a Fatigue Failure in a Welded Joint of an Aluminum Alloy

of the Al–Cu–Mn System

ویژگی های سیگنال انتشار آکوستیک در طول شروع یک شکست خستگی

در یک اتصال جوش داده شده آلیاژ آلومینیوم سیستم Al-Cu-Mn

ABSTRACT

The features of the generation of acoustic emissions (AEs) during the initiation of a fatigue failure in various zones of a welded joint of thermally hardened 2219T6grade aluminum alloy, which is produced using electronbeam welding, are  considered. Metallographic studies showed that a welded joint of the alloy is structurally and mechanically inhomogeneous. This predominantly influ ences the initiation and development kinetics of fatigue cracks in the joint and the AE kinetics. It is shown that the area of a formed flaw is proportional to the sum of the amplitude of detected signals, and the transition from the initiation to the stable propagation of a failure is accompanied by an abrupt increase in AE activity.


 

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جوشکاری تیگ آلومینیوم و منیزیم

اتصال آلومینیوم و منیزیم از طریق جوشکاریA-TIG

 با پیش نورد کمکی همراه با لایه میانی روی 

ABSTRACT

AZ31B Mg and 6061 Al alloys were successfully welded via a novel pre-roll-assisted A-TIG welding technique with Zn interlayer at an overlap configuration. The rolling operation increased the contact area and control tightly between Zn interlayer and plates at an interlayer-assisted overlap configuration to avoid the adverse effect of gaps. B2O3 activating flux was coated on the upper Al plates to provide contraction of the arc column to increase the arc energy density; welding penetration was increased without improving heat input, which reduced the formation and grain coarsening of Al–Mg IMCs. Therefore, the tensile–shear strength of the joints was improved obviously. The average of tensile–shear strength joined was 71.2 MPa with a maximum of 74 MPa compared to 41.1 MPa with a maximum of 45.2 MPa by conventional TIG with Zn interlayer.


  

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جوشکاری اینکونل 625 و فولاد زنگ‎نزن L 304 با پرتوی الکترونی

Microstructure and hardness studies of electron beam

welded Inconel 625 and stainless steel 304L

مطالعه ریزساختار و سختی اینکونل 625 و فولاد زنگ‎نزن L 304

جوشکاری شده با پرتوی الکترون

ABSTRACT

In this study, electron beam welding of dissimilar Inconel 625 and SS 304L alloys was successfully performed by employing optimized electron beam welding parameters. The welded joint was characterized using SEM/EDS, XRD and micro-hardness tester. The welded joint was found homogeneous, well bonded and defect free. Two types of microstructure i.e. columnar dendritic and cellular dendritic were observed in the fusion zone. The development of different microstructures in the fusion zone was attributed to the localized cooling effects during solidification. Few micro-cracks along with dendrites splitting were observed in the vicinity of end crater that was mainly due to the segregation of S element. A significant variation of Ni and Fe was observed across Inconel/FZ and FZ/SS interfaces due to their fast diffusion in the melt pool. Micro-hardness measurements across Inconel/FZ and FZ/SS interfaces showed an increasing trend in the FZ from SS 304L towards Inconel base alloy.


  

ادامه مطلب ...

جوشکاری آلیاژ Al–Cu–Mg–Mn به روش تیگ

Effect of welding parameters on the solidification microstructure

of autogenous TIG welds in an Al–Cu–Mg–Mn alloy

تاثیر پارامترهای جوشکاری بر میکروساختار انجمادی جوش های TIG

بدون ماده پر کننده در یک آلیاژ Al–Cu–Mg–Mn

ABSTRACT


The weld metal microstructures of autogenous TIG welds have been investigated for a range of welding conditions using an Al–Cu–Mg–Mn alloy. It was found that a combination of high welding speeds and low power densities provide the thermal conditions required for the nucleation and growth of equiaxed grains in the weld pool, providing heterogeneous nucleation sites are available. The most likely origin of the nucleants is from a combination of dendrite fragments and TiB2 particles that survive in the weld pool. The finest microstructure was observed in the centre of the weld and is attributed to the higher cooling rates which operate along the weld centreline. Composition profiles across the dendrite side arms were measured in the TEM and were found to follow a Scheil type segregation behaviour where there is negligible back diffusion in the solid. The measured core concentration of the dendrite side arms was found to rise with increasing welding speed and was attributed to the formation of significant undercoolings ahead of the primary dendrite tip, which enriched the liquid surrounding the dendrite side arms.

 

  

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تنش‌های پسماند در جوش‌های لب به لب اتصالات لوله غیرمشابه

Effect of the welding heat input on residual stresses in butt-welds of dissimilar pipe joints

اثر ورودی حرارت جوشکاری بر تنش‌های پسماند در جوش‌های لب به لب اتصالات لوله غیرمشابه

ABSTRACT

This study used finite element techniques to analyse the thermo-mechanical behaviour and residual stresses in dissimilar butt-welded pipes. The residual stresses at the surface of some weld specimens were measured experimentally by using the hole-drilling method. The results of the finite element analysis were compared with experimentally measured data to evaluate the accuracy of the finite element modelling. Based on this study, a modelling procedure with reasonable accuracy was developed. The developed finite element modelling was used to study the effects of welding heat input on magnitude and distribution of welding residual stresses in butt-welded pipes made of ferritic and austenitic steels. The hoop and axial residual stresses in dissimilar pipe joints of 8 mm thick for V-groove shape were studied. It is shown that the welding heat input has a significant effect on magnitude and distribution of residual stresses in the stainless steel side of the studied joints.

 

  

ادامه مطلب ...

تنش پسماند حرارتی در فرآیند جوشکاری لیزری هیبریدی-GMA welding process

Numerical and experimental study of thermally induced residual stress in the hybrid laser–GMA welding process

مطالعه عددی و تجربی تنش پسماند حرارتی در فرآیند جوشکاری لیزری هیبریدی-GMA


ABSTRACT

A model based on a double-ellipsoidal volume heat source to simulate the gas metal arc welding (GMAW) heat input and a cylindrical volume heat source to simulate the laser beam heat input was developed to predict the temperature field and thermally induced residual stress in the hybrid laser–gas metal arc (GMA) welding process. Numerical simulation shows that higher residual stress is distributed in the weld bead and surrounding heat-affected zone (HAZ). Effects of the welding speed on the isotherms and residual stress of the welded joint are also studied. It is found that an increase in welding speed can reduce the residual stress concentration in the as-weld specimen. A series of experiments has been performed to verify the developed thermo-mechanical finite element model (FEM), and a qualitative agreement of residual stress distribution and weld geometrical size is shown to exist.

 

 

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