دنیای جوشکاری
دنیایی از مطالب جوشکاری و بازرسی فنیدنیای جوشکاری
دنیایی از مطالب جوشکاری و بازرسی فنیمکانیزم نفوذ فلاکس در جوشکاری تیگ برای آلیاژ آلومینیوم
Study of mechanism of activating flux increasing
weld penetration of AC A-TIG welding for aluminum alloy
مطالعه مکانیزم افزایش مکانیزم نفوذ فلاکس فعال ساز جوشکاری AC A-TIG
برای آلیاژ آلومینیوم
ABSTRACT
When multi-component flux AF305 is used as surface activating flux for an aluminum alloy, the weld penetration of activating flux-tungsten inert-gas (A-TIG) welding is over two times more than that of conventional TIG welding. Using A-TIG welding with the modes of alternating current (AC), direct current electrode negative (DCEN) and direct current electrode positive (DCEP), respectively, the flux differently affects weld penetration when the polarity is different. After studied the effect of compelled arc constriction on weld penetration of AC welding, it is believed that the constriction of the whole arc root is not the main mechanism that flux AF305 dramatically improves weld penetration. The penetration has a relationship with the separate distribution of slag on the weld surface. Then, an observation of scanning electron microscopy (SEM) and an electronic data systems (EDS) analysis of slag were performed respectively. The separate distribution of slag on the weld pool during welding and the great constriction of arc spots were confirmed by TIG welding with helium shielding gas. The relationship between slag distribution and weld penetration was studied by adding aluminum powder into flux AF305 to change the distribution of slag. During welding, the separate distribution of slag on the weld pool results in the great constriction of arc spots, an increase in arc spot force, and an increase in Lorentz force within the arc and weld pool. Finally, the weld penetration is increased.
شرایط جفت شدگی ضعیف جوشکاری مقاومتی نقطه ای
Poor fit-up condition in resistance spot welding
شرایط جفت شدگی ضعیف جوشکاری مقاومتی نقطه ای
ABSTRACT
An experimental setup for poor fit-up condition research, which makes it possible to analyze poor fit-up conditions of different intensities and also quantify them is presented. The intensity of poor fit-up condition can be estimated by measuring the welding force during the initial contact between the electrode tips and the weldpieces. In order to reduce the negative influence of the poor fit-up condition on weld strength an addition of preheating phase was studied. Although it helps to increase the weld strength, a significant gap remains between the weld strength of non-deformed welds and poor fit-up welds even at large preheating currents.
استحکام جوش و چقرمگی در جوشکاری اینکونل 625 و فولاد ضد زنگ سوپر دوپلکس
Characterization of weld strength and toughness in
the multi-pass welding of Inconel 625 and
Super-duplex stainless steel UNS S32750
مشخصه‌یابی استحکام جوش و چقرمگی در جوشکاری چند پاس
اینکونل 625 و فولاد ضد زنگ سوپر دوپلکس UNS S32750
ABSTRACT
The present study investigated the weldability of dissimilar metals involving Inconel 625 and Super-duplex stainless steel obtained from continuous current (CC) and pulsed current (PC) gas tungsten arc welding (GTAW) processes employing ER2553 and ERNiCrMo-4 fillers. A comparative analysis on these dissimilar weldments was carried out to establish the structure-property relationships. Microstructure examination was carried out using optical microscopy (OM) and scanning electron microscopy (SEM) techniques. Grain coarsening was observed at the HAZ of UNS S32750 for all the cases. Mechanical tests ascertained that the PCGTA weldments employing ERNiCrMo-4 offered better weld strength and impact toughness. Elaborative studies on the structure – property relationships of these dissimilar weldments were discussed.
اتصال Inconel 625 به UNS 32205 به روش جوشکاری پرتو الکترونی
Investigations on the structure – Property relationships of
electron beam welded Inconel 625 and UNS 32205
بررسی روابط خواص-ساختار اتصال Inconel 625 به UNS 32205
به روش جوشکاری پرتو الکترونی
ABSTRACT
The metallurgical and mechanical properties of electron beam welded Ni based superalloy Inconel 625 and UNS S32205 duplex stainless steel plates have been investigated in the present study. Interface microstructure studies divulged the absence of any grain coarsening effects or the formation of any secondary phases at the heat affected zone (HAZ) of the electron beam (EB) weldments. Tensile studies showed that the fracture occurred at the weld zone in all the trials and the average weld strength was reported to be 850 MPa. Segregation of Mo rich phases was witnessed at the inter-dendritic arms of the fusion zone. The study recommended the use of EB welding for joining these dissimilar metals by providing detailed structure – property relationships.
اثر ارتعاش مکانیکی روی ریزساختار مادهی جوشکاری
Studies on the Effect of Mechanical Vibration on
the Microstructure of the Weld Metal
تحقیقات در مورد اثر ارتعاش مکانیکی روی ریزساختار مادهی جوشکاری
ABSTRACT
The solidification process in the weld metal produces solidification structure. The solidification process depends on the thermal gradient, solidification speed and the alloy content. These structures can be planar, cellular, columnar dendritic and equiaxed dendritic. The solidification process may change from planar to cellular, columnar dendritic and equiaxed dendritic across the weld metal zone as shown in fig.1. Three grains are shown to grow epitaxially from the fusion line. A short distance away from the fusion line, solidification changes to the cellular mode. Further away from the fusion line, the solidification changes to columnar dendritic mode. Near the weld centre line equiaxed dendrites nucleate and grow, blocking off the columnar dendrites. Each one of these structures would affect the hot cracking susceptibility in greater or smaller extent.
ادامه مطلب ...
جوشکاری اصطکاکی لحظه ای (IFW) برای کاربردهای هوافضا
Inertia friction welding (IFW) for aerospace applications
جوشکاری اصطکاکی لحظه ای (IFW) برای کاربردهای هوافضا
ABSTRACT
The use of inertia welding in the aerospace industry has been steadily increasing owing to the signifi cant improvements it provides in joint quality, compared with the use of fusion welding. This chapter introduces the process, with respect to its operation, parameters, differences from other friction welding techniques and equipment. It also explains the application of the technique and the selection of the process parameters, and the different mathematical, analytical and numerical approaches that are used to model the thermal fi elds and residual stress development. Details of the microstructural, mechanical properties and residual stress development in inertia friction-welded Ni-based superalloys, titanium alloys, steels and other alloys are also discussed.
اتصال با استفاده از تغییرشکل پلاستیک
Joining by plastic deformation
اتصال با استفاده از تغییرشکل پلاستیک
ABSTRACT
Vehicles such as aircraft and cars comprise a large number of mechanical parts produced by a variety of manufacturing processes. Cars generally consist of 10,000–30,000 parts, and the number of parts in aircraft is counted in millions. A trend in manufacturing such products is that both the number of parts and their complexity are increasing, including new combinations of dissimilar materials. Welding, adhesive bonding and mechanical fastening are typically used to join components during product assembly. In fusion welding, workpieces are joined by the application of an external heat source which melts material around the interface. Although the use of welding is widespread, the high temperatures required may reduce the quality, accuracy and reliability of joined parts. The strength of adhesively bonded and mechanically fastened joints is almost always lower than that achieved by welding. Commercial requirements for higher performance, higher productivity and lower cost in joining operations are becoming more demanding. In addition, strong joining of dissimilar materials is increasingly required. For example, high strength steel and aluminium sheets must be joined in some current car models, to allow weight reduction. There is therefore a need to identify new joining methods for new applications and materials.
سیلان مواد در طول جوشکاری اصطکاکی اغتشاشی Ti-6Al-V
Material Flow During Friction Stir Welding of Ti-6Al-4V
سیلان مواد در طول جوشکاری اصطکاکی اغتشاشی Ti-6Al-V
ABSTRACT
6 mm thick Ti-6Al-4V butt joints were produced with a tracer material embedded in the joint under a variety of process conditions, namely rotational speed and traversing speed, in an attempt to relate the welding process parameters to the material flow behavior via post weld radiographic and metallographic evaluations. It was found that by embedding refractory alloy powder into the joint line, welding through it, and subsequently x-raying the joint, the material flow patterns could be examined. The tracer material was distributed over a wider area in the weld zone relative to its starting position, implying a fair amount of mixing occurred even though little vertical movement of the tracer material was observed. There was minimal effect of material flow patterns as a function of welding parameters observed using the tracer material and radiographic examination, but defect formation in the root, where there was no tracer material, examined by cross sectional metallographic evaluations were found to be dependent on the rotational speed and traversing speed conditions. Lack of penetration defects were generally associated with relatively “cold” welding conditions (low rotational speed/high traversing speeds) and voids with “hot” conditions (high rotational speed/low traversing speeds).
جوشکاری حالت جامد آلیاژ برنج Cu-Zn و فولاد