Computational modelling of dynamic recrystallisation of Ni-based superalloy during linear friction welding

Linear friction welding (LFW) is an advanced joining technology used for manufacturing and repairing complex assemblies like blade integrated disks (blisks) of aeroengines. This paper presents an integrated multiphysics computational modelling for predicting the thermomechanical-microstructural processes of IN718 alloy (at the component-scale) during LFW. Johnson–Mehl–Avrami-Kolmogorov (JMAK) model was implemented for predicting the dynamic recrystallisation of γ grain, which was coupled with thermomechanical modelling of the LFW process. The computational modelling results of this paper agree well with experimental results from the literature in terms of γ grain size and weld temperature. Twenty different LFW process parameter configurations were systematically analysed in the computations by using the integrated model. It was found that friction pressure was the most influential process parameter, which significantly affected the dynamic recrystallisation of γ grains and weld temperature during LFW. The integrated multiphysics computational modelling was employed to find the appropriate process window of IN718 LFW.

Effect of friction time on tensile strength and metallurgical properties of friction welded dissimilar aluminum alloy joints

Dissimilar (AA6061 & AA7075-T6) friction welded aluminum joints were taken into the investigation to correlate the influences of friction time on tensile and metallurgical properties. The dissimilar metals were welded by varying the friction time from 2 s to 6 s with the following constant parameters: a rotating speed of 1200 rpm, friction pressure of 35 MPa, upset pressure of 35 MPa, and upset time of 3 s. The higher friction time during joint fabrication needs to be selected to attain good metallurgical bonding between rubbing surfaces. The highest tensile strength of 228 MPa was attained when the friction time was given as 4 s. Furthermore, the increase in friction time widened the width and reduced the hardness of the heat affected zone on the AA6061 side where joint failure occurred. Finally, the metallurgical features of the dissimilar specimens were characterized using optical microscopy, scanning electron microscopy, and X-ray diffraction. Other details related to the characterization and results of the testing were recounted.

INFLUENCE OF GAS-DYNAMIC TESTING RIG PIPELINES MATERIAL ON THEIR DYNAMIC CHARACTERISTICS

Приведено исследование зависимости газодинамических характеристик стенда от применяемого материала трубопровода. Oсновополагающими факторами, влияющими на работоспособность стенда, являются выходные параметры - давление и расход рабочего тела, которые напрямую зависят от потерь давления на трение, создаваемого элементами стенда. Для оценки степени влияния материалов на потери стенда выбраны два вида труб: полипропиленовые и металлические. Аналитические расчёты потери давления рассматриваемых трубопроводов из различного материала показали, что трубопроводы из полипропилена предпочтительнее. Однако при проведении эксперимента получены противоположные данные, которые показали, что в полипропиленовых магистралях возможно присутствие значительного количества диафрагм: в местах пайки труб, образовавшихся в процессе изготовления. Именно этот факт способствует существенному повышению значений сопротивлений в полипропиленовых трубопроводах на 20 % по сравнению со стальными трубами, где диафрагмы отсутствуют. В результате проведения исследования был введен коэффициент, учитывающий влияние диафрагм полипропиленового трубопровода при аналитическом расчете на сопротивление. Для сохранения более точных снимаемых значений с газодинамических стендов целесообразнее использовать трубопроводы из металла, в которых рассчитать потери возможно с отклонениями до 3 % Here we give the study of the dependence of the gas-dynamic characteristics of the stand on the pipeline material used. The fundamental factors affecting the performance of the stand are the output parameters-the pressure and flow rate of the working fluid, which directly depend on the friction pressure losses created by the elements of the stand. To assess the degree of influence of materials on the losses of the stand, we selected two types of pipes: polypropylene and metal. Analytical calculations of the pressure loss of the considered pipelines made of various materials have shown that pipelines made of polypropylene are preferable. However, during the experiment, we obtained the opposite data, which showed that a significant number of diaphragms may be present in polypropylene pipelines: in the places of soldering of pipes formed during the manufacturing process. This fact contributes to a significant increase in the resistance values in polypropylene pipelines by 20 % compared to steel pipes, where there are no diaphragms. As a result of the study, we introduced a coefficient that takes into account the influence of polypropylene pipeline diaphragms in the analytical calculation of resistance. To preserve more accurate values taken from gas-dynamic stands, it is more expedient to use metal pipelines in which it is possible to calculate losses with deviations of up to 3 %

Exploration of Rotary Friction Welding Technique

Friction welding is a solid-state welding system which welds materials without authentic melting it. This study explores papers of different researchers on the friction welding method and it has been observed that the welding parameters like friction time; friction pressure, forge time and forge pressure highly affect properties of welded joints. The reason for this investigation is to exhort industry and the insightful world regarding advantages of revolving friction welding so the technique may be utilized in an ideal manner.

Collaborative Approach Overcomes Cementing Challenges in Narrow Pressure Window Environment

The collaborative approach used for cementing the production liner in an onshore development well in Russia is presented. The reservoir has a narrow window between pore and fracture pressures, which has previously caused formation instability and severe lost circulation issues during well construction, compromising zonal isolation objectives. Total loss of fluids experienced while cementing the 114.3 mm production liner in the first appraisal well in the field led to revising the cementing strategy. Collaboration among various parts of the drilling department and the opportunity to define a new approach resulted in a decision to introduce managed pressure drilling (MPD) to address the challenges associated with a narrow pressure window and uncertainty in pore pressure while drilling and cementing. This enabled implementing the optimal mud weight and adjusting equivalent circulating density (ECD) during cementing with minimum overbalance. Reducing the mud weight from 1.20 SG to 1.05 SG eliminated losses after running the liner and while cementing it. As a result, pre-job circulation rates and pumping rates during cementing could be increased, improving mud removal efficiency and achieving top of cement at the required depth. The constant-bottomhole-pressure mode of MPD was used to maintain the same ECD during displacement of the well to a lighter fluid and during cementing, avoiding well influx during pumpoff events by compensating for the annular friction pressure loss with surface backpressure. This first onshore managed pressure cementing operation executed within the same field in Russia (later named as field A) was completed flawlessly, with no safety or quality issues, zero nonproductive time, and achievement of the required zonal isolation across the challenging production section. The collaborative approach used was a novel strategy, with the mud weight program strategically adjusted before and during the cementing operation to achieve zonal isolation objectives.

Influence of Rotary Friction Welding Parameters on Tensile Strength and Length of TMAZ of Dissimilar Welded Joints from 32G2 and 40KhN Steels

In this work, pipe billets with a diameter of 73 mm and a wall thickness of 9 mm from steels 32G2 and 40KhN are friction welded with an aim to optimize the process parameters. The friction pressure, the forging pressure and the length of the fusion varied. After the implementation of various welding modes, tensile tests and metallographic studies were carried out. The optimal welding parameters have been established, which make it possible to obtain tensile strength at the level of the 32G2 base metal. The study results of the microstructure and SEM fractographs after the optimal welding mode are presented.

Effect of Friction Pressure on Microstructure and Properties of Friction Welded Joints of Pure Aluminum/304 Stainless Steel

Continuous drive friction welding was used to realize the high quality connection between pure aluminum and 304 stainless steel. The composition of interface micro-zone and mechanical properties of joint were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), tensile test and hardness test. The formation mechanism of intermetallic compound (IMC) during friction welding was discussed. The results show that under the experimental parameters, the joint surface is uneven and two intermetallic compounds, Fe2Al5 and FeAl3, are formed. With the increase of friction pressure, the mechanical bonding degree of the joint decreases, the metallurgical bonding degree increases, the element diffusion distance increases from 1.4 to 1.9 um, the tensile strength of the joint can reach or even higher than that of the base metal on the aluminum side, and the maximum hardness increased from 414 HV to 447 HV.

Joining of ceramic to metal by friction welding process: A review

In this paper, the recent progress in friction welding of alumina along with its various composites to metals is thoroughly investigated and compared. Among the existing methods of joining ceramics to metals, the friction welding process seems to be a reliable approach that provides promising joint properties. A relationship is established between processing parameters, their resultant microstructures, and their associated mechanical properties. The material properties and the environmental factors are taken into account while manifesting this comparison. The influence of various factors such as rotations per minute (r/min), friction pressure, and friction time on mechanical properties is critically analyzed. However, several challenges that must be addressed appropriately to achieve these joints and to fabricate the same have been discussed.

Analisis Pengaruh Variasi Beban Terhadap Kekuatan Tarik Hasil Friction Welding pada Baja Karbon Sedang

Proses penyambungan logam dengan metode pengelasan gesek (friction welding) dimana logamnya tanpa melalui pencairan (solid state proces) yaitu proses pengelasan terjadi akibat adanya gesekan antara permukaan logam yang akan disambungkan dengan ketentuan ada minimal salah satu logam yang berputar. Gesekan yang terjadi akan menghasilkan panas yang dapat melumerkan kedua ujung logam hingga akhirnya akan menyatu. Adapun parameter penting dalam proses pengelasan gesek meliputi friction time, rotational speed, friction pressure, dan proses pengereman. Tujuan dari penelitian ini adalah; mengetahui pengaruh variasi beban terhadap kekuatan tarik hasil pengelasan gesek menggunakan baja karbon sedang, dan mengetahui perubahan kekuatan tarik baja karbon sedang hasil pengelasan gesek. Hasil pengujian dan perhitungan memperlihatkan bahwa semakin besar beban yang diberikan pada saat proses las gesek maka semakin besar pula tegangan tarik bahan (baja karbon rendah) dimana perbandingan yang terjadi adalah berbanding lurus seperti yang diperlihatkan dari hasil perhitungan. Tegangan tarik terendah diperoleh pada saat beban 4 kg yaitu 7,67 kN/mm2 sedangkan tegangan tarik terbesar diperoleh pada beban 8 kg yaitu 10,46 kN/mm2 dengan modulus elastisitas 48,29 Pa.