دنیای جوشکاری
دنیایی از مطالب جوشکاری و بازرسی فنیدنیای جوشکاری
دنیایی از مطالب جوشکاری و بازرسی فنیاستحکام 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.
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.
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.
جوشکاری لیزر CP Ti به فولاد زنگ‌نزن با شکل‌های ضربان زمانی مختلف
Laser welding of CP Ti to stainless steel with
different temporal pulse shapes
جوشکاری لیزر CP Ti به فولاد زنگ‌نزن با شکل‌های ضربان زمانی مختلف
ABSTRACT
CP Ti and stainless steel sheets were laser welded by using a pulsed wave Nd:YAG laser welding system. The effect of pulse profiles used in laser welding was studied by investigating weld appearance, weld geometry, microstructure, hardness variation, joint strength and failure mode of welds. Weld quality was strongly affected by the temporal pulse profile adopted in laser welding. In comparison with the use of a normal rectangular pulse profile, stronger welds with a better homogeneity and a complex fracture mode were achieved by using a ramp-down pulse profile. This quality enhancement was contributed from the less degree of intermixing between two welding materials in melting pools.
جوشکاری فلزات دیرگداز (نیوبیوم، تانتالیوم، مولیبدن و تنگستن) و لحیم کاری گرم آن ها
The welding and brazing of the refractory metals
niobium, tantalum, molybdenum and tungsten
مروری بر جوشکاری و لحیم کاری گرم فلزات دیرگداز
نیوبیوم، تانتالیوم، مولیبدن و تنگستن
ABSTRACT
This review covers the present and future problems in the development and welding of niobium, tantalum, molybdenum and tungsten and their alloys. Their metallurgical characteristics are discussed together with the influence of impurities and alloying elements on mechanical properties, alloy development and weldability. Other factors briefly discussed are availability, high temperature strength, ductility and oxidation resistance.
اثر پارامترهای جوشکاری ترمیمی بر عمر مفید قالب های دایکست
Effect of repair-welding parameters on life time of
die casting moulds
اثر پارامترهای جوشکاری ترمیمی بر عمر مفید قالب های دایکست
ABSTRACT
In die casting, H13 hot working tool steels are exposed to heat shocking and cracking due to the thermal fatigue which is exerted by die casting process. The gradual destruction of mould surfaces during the service, decreases casting piece quality and limits the mould life time. These moulds are expensive and replacing of them is the main problem of the die casting industries therefore repair-welding of die casting moulds can be helpful. H13 steel has low weldability because of the significant hardening resulted from large amounts of alloying elements. Within this study, results were obtained on the performance of repair welded parts that were welded by three types of filler metals on the thermal fatigue test. The filler metals that are used in this study are H13 tool steel, maraging steel and Co-base alloy. Maximum and minimum life time of the repair welded parts of die casting mould in the thermal fatigue test were obtained from Co-base alloy and H13 hot work steel filler metals, respectively. Repair-welding by maraging filler metal shows the intermediate life time. It seems that repair-welding of H13 moulds by maraging filler metals is more economic because of its lower price in comparison with the Co-base filler metal.
جوشکاری اصطکاکی اغتشاشی صفحات AA 2219 نورد شده
Interface behaviours and mechanical properties of filling friction stir weld joining AA 2219
رفتارهای فصل مشترک وخواص مکانیکی جوشکاری اصطکاکی اغتشاشی
پرکردن اتصال AA2219
ABSTRACT
Being brittle and having low thermal conductivity, refractories suffer damage and sometimes fail in service as a result of thermal shock. While the approach of those making fine-grained technical ceramics is to make their products sufficiently strong to withstand thermal stresses the refractory technologist is more cunning. He uses, often little known, devices to provide resistance to thermal shock that minimise but do not eliminate damage to the component. In this paper the basic equations of thermal conduction and elasticity are presented and followed by some immediate results that should guide the designer of components subject to severe thermal environments. The influence of size and shape of the refractory components is then discussed along with ways in which refractory producers can engineer the thermal and mechanical properties. In particular, the methods used to tailor fracture behavior to optimize the thermal shock resistance are treated in some detail.
تاثیر انجماد بر تحول ریزساختاری فلز جوش پایه نیکل
Influence of solidification on the microstructural evolution
of nickel base weld metal
تاثیر انجماد بر تحول ریزساختاری فلز جوش پایه نیکل
ABSTRACT
The effect of segregation resulting from solidification on the microstructural evolution of nickel base alloys was investigated. Two different groups of alloys were produced to simulate either the Hastelloy C type or the Inconel 625/718 type of alloys. Gravitational thermal analysis welding was performed on these experimental alloys and the extent of microsegregation in the weld metal was determined. Using composition profiles obtained from solidified microstructures, predictions of the phase stability of these microstructures were made based on metal d-level (Md) calculations. The maximum Md values obtained in these microstructures were compared with those critical to the formation of topologically close-packed (TCP) phases such as sigma, P, and Laves. These profiles showed an increase in the Md level in the interdendritic regions which was correlated to the formation of TCP phases.
الزامات پاکیزگی برای فولادهای X80 و X65 خط لوله جوشکاری‌شده
Steel cleanness requirements for X65 to X80
electric resistancewelded linepipe steels
الزامات پاکیزگی برای فولادهای X80 و X65 خط لوله جوشکاری‌شده
به روش مقاومت الکتریکی
ABSTRACT
CONTROL OF OXIDES AND SULPHIDES : Clean steel practices at the BHP Steel Ltd, Flat Products plant have always been related to customers’ requirements and expectations. Monitors were developed for critical cleanness grades from either in-house tests or from customer supplied data. Some of these monitors have been in existence for nearly 20 years and have successfully guided process improvements both in steelmaking and in continuous slab casting, such as ladle opening with submerged shroud, vibration ladle slag detection, argon shielding of delivery systems, weir wall design, and quick melting ux addition to the tundish on start up.
اثر هیدروژن بر روی تافنس شکست فلز جوش در فولاد زنگ نزن دوفازی
Hydrogen influence on fracture toughness of the weld metal in
super duplex stainless steel (UNS S32750) welded with two different heat input
اثر هیدروژن بر روی تافنس شکست فلز جوش در فولاد زنگ نزن دوفازی
(UNS S32750) جوشکاری شده با دو حرارت ورودی مختلف
ABSTRACT
The super duplex stainless steels have a microstructure composed by two phases, ferrite (α) and austenite (γ). This dual microstructure improves simultaneously the mechanical and corrosion resistance properties. However, the welding of these steels is often a critical operation. The present work evaluated the fracture toughness through critical tip open displacement (CTOD) tests of welded joints, with two different heat input, 1.1 kJ mm−1 and 2.0 kJ mm−1. The steel used was a super duplex stainless steel (UNS S32750) in presence of hydrogen. The CTOD tests (according BS 7448-1 and BS 7448-2 standards) were performed in air and under different times of hydrogenation. The procedure of hydrogenation has been performed using cathodic potential of −1400 mVSCE by 96 and 360 h. The microstructural analysis allowed to determine relevant aspects (α/γ balance, inter austenitic spacing and γ morphology) and to compare with CTOD results. The results showed strong evidence that the reductions of CTOD values is related to differences in the γ2 morphologies. Another important result was the high statistic dispersion in the measures of austenitic spacing, according DNV RP F112-08, which implies in low reliability of using this standard in presence of high anisotropy. The paper also aims to discuss and evaluate which is the best approach to hydrogenated duplex stainless steels: linear elastic fracture mechanics or elasto plastic fracture mechanics.