Engenharia Mecânica
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/23
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Artigo de evento 0 Citação(ões) na Scopus Investigation of residual stress in laser welding dissimilar materials Investigação da tensão residual na soldagem laser de mate riais dissimilares(2010-07-26) MIRIM, D. DE C.; BERRETTA, J. R.; ROSSI, W. DE; LIMA, N. B. DE; OLIVEIRA, R. R. DE; Sergio Delijaicov; GOMES, D. O.One of the most critical problems found in the different materials welding is the residual stress formation, that happens mainly for the fact of those materials they possess coefficients of thermal expansion and different thermal conductivities. Like this in this work the residual tension was evaluated in the technique of welding laser among the steel low carbon, AISI 1010 and AISI 304. The materials were united for it welds autogenous of top with a laser of continuous Nd:YAG in that they were varied the potency, speed and the focus of the laser stayed constant in relation to surface of the sample. The main objective of the study went identification and to analysis of the residual stress in HAZ on both sides of seem. Um planning factorial of two factors at two levels each it was executed for optimization the combination of the factors potency and speed. The obtained answers were the residual stress in different depths in HAZ. In the surface of the sample measures of residual stress were accomplished by the technique of X-ray difraction. The hole drilling strain gage method it was applied to measure the residual stress on both sides of the union. The results were analyzed using the variance analysis and the statistical regression based on the different influences of the entrance and combination of the factors in the residual stress generated in that union. The results indicate that the development of models can foresee the answers satisfactorily.- Surface integrity analysis in machining of hardened AISI 4140 steel(2017-01-23) STIPKOVIC, M. A.; Ed Claudio Bordinassi; Farias, Adalto; Sergio DelijaicovThis study aimed to analyze the residual stresses and roughness in finishing milling of AISI 4140 steel, quenched and tempered up to hardness of 58 HRC. Machining operations were performed with the use of CBN inserts and by varying three basic cutting parameters (cutting speed, feed per tooth and cutting depth). Hardened materials are typically machined by abrasive processes, which in turn are more expensive and complex to be studied due to the undefined cutting geometry of the grinding wheel. A series of machining tests with milling process and CBN tools was implemented in order to study the resultant condition of the specimeńs surface. An experimental design was used and the results were statistically treated, enabling the generation of a model that aims to obtain roughness values due to the optimization of three adopted cutting parameters. The roughness values found in the range of Ra 0,16 to 0,4 μm indicate that it is possible to use the milling process with CBN tools for finishing, reducing machining time and the cost of the machined part. The generated residual stresses were compressive and the feed per tooth parameter showed greater influence in this result. The research was limited to test only one type of CBN insert, which was constantly replaced, preventing the influence of tool wear on responses. The geometry of the tool as well as the use of cutting fluid were not considered. Milling process with CBN inserts is confirmed as a possibility for replacing grinding process for finishing machining leading to significant gains in machining time. An optimized model was derived to predict the value of the roughness and three optimizations were made to specify the best cutting parameters to desirable answers such as better roughness, higher compressive residual stresses and low cutting forces, for example.
- Effect of hybrid manufacturing (am-machining) on the residual stress and pitting corrosion resistance of 316L stainless steel(2022-10-05) Ed Claudio Bordinassi; MHURCHADHA, S. U.; SERIACOPI, V.; Sergio Delijaicov; LEBRÃO, S. M. G.; THOMAS, K.; BATALHA, K.; RAGHAVENDRA, R.© 2022, The Author(s), under exclusive licence to The Brazilian Society of Mechanical Sciences and Engineering.The use of additive manufacturing (AM) has grown exponentially in recent years and has many advantages, including feasibility, over other conventional processes in many current applications. The use of a second process, for example, machining, improves the surface finish and in this case, the use of two processes is known as hybrid manufacturing. Heat treatments are often performed on parts generated by the AM process, mainly to relieve the residual stresses generated, but for some materials, this can decrease the pitting corrosion resistance of the parts. The objective of this study is to analyze the effect of hybrid manufacturing (AM + machining) on residual stresses and pitting resistance corrosion, which can bring advantages to piece properties without the use of heat treatment. 316L stainless steel parts are generated by direct laser metal sintering (DLMS), with subsequent milling using a complete factorial planning for the design of the experiments. The cutting speed, feed rate, cutting depth, use of the cutting fluid and laser power in the DLMS process are all varied. Residual stresses are measured by X-ray diffraction and the blind hole method, with polarization curves raised by a potentiostat. The results show that it is possible to reduce the residual surface stresses in the parts, even for compressive stresses, and to improve the pitting corrosion resistance, when compared to the part without milling, depending on the cutting parameters used.
- Residual stresses measurements using strain gages - aluminum wheels(2012-11-06) CIONE, F. C.; ROSSI, J. L.; SOUZA, A. C.; Sergio Delijaicov; COLOSIO, M. A.Many engineering specifications, manufacturing procedures, inspection and quality control have begun to require that the residual stress of a particular component be evaluated. This is becoming as commonplace as the demands on the mechanical properties. In the country there are few research laboratories qualified to perform these tests and also found a worrying lack of skilled labor. Studying the formation and distribution of residual stress fields will improve the operational criteria of wheel safety, among other gains. It is known that these residual stress fields could be added to the effects of system load (tare weight plus occupation of vehicle traction, braking and torque combined). The results obtained used drilling method and rosette type strain gages, are convergent with similarity to those obtained using FEA simulation over critical region for global and superficial in principal stresses mode. The relevance of the present study and research on residual stresses meets safety improvements in car's wheel industry. © (2012) Trans Tech Publications, Switzerland.
- The effect of process parameters and cutting tool shape on residual stress of SAE 52100 hard turned steel by high speed machining(2020-04-26) PASCHOALINOTO, N. W.; Ed Claudio Bordinassi; Roberto Bortolussi; Fabrizio Leonardi; Sergio DelijaicovThis study focused on determining the residual stress of SAE 52100 hard-turned steel. The objective was to evaluate and compare the effects of the cutting-edge geometry and cutting parameters (cutting speed, feed rate, and cutting depth) on the residual stresses of three different conventional inserts: S-WNGA08 0408S01020A 7025, T-WNGA08 0408T01020A 7025, and S-WNGA432S0330A 7025. Tests were performed on 60 samples of SAE 52100 hardened steel with an average hardness of 58.5 HRC. The circumferential residual stresses of the samples were measured by X-ray diffraction. A full factorial design of experiments with three factors and two levels each with two central points and a replicate was used for a statistical analysis. The most significant results were as follows: For all inserts, the measured residual stresses were compressive, which extended the tool lifespan. The residual stresses of the Type-S inserts were significantly influenced by the cutting speed and depth, and those of the Type-T insert were significantly influenced by the feed rate and cutting depth. In addition, the residual stresses of the insert 3 were more compressive than those of the other two types of inserts. In other words, residual stresses are more compressive for inserts with larger chamfer angles even as the principal residual stress profiles were all compressive. This work has also shown that it is possible to determine a significant statistical relationship between cutting forces and residual stresses, allowing force measurements to predict the residual stress without any information on process parameters.
- Microhardness and residual stress of dissimilar and thick aluminum plates AA7181-T7651 and AA7475-T7351 using bobbin, top, bottom, and double-sided FSW methods(2020-05-12) Sergio Delijaicov; RODRIGUES, M.; FARIAS, A.; NEVES, M. D.; Roberto Bortolussi; MIYAZAKI, M.; BRANDÃO, F.Friction stir welding (FSW) is a relatively new manufacturing process (invented in 1991 at the Welding Institute, UK) and more than 5000 scientific articles have been published in the past 10 years in indexed journals demonstrating the robustness of the research. However, further research is necessary to ensure safe use of the technique for structural components, particularly with reference to the aeronautics industry. Residual stresses and their consequences on the life of welded products must be fully understood, in addition to their correlations with other properties such as hardness, strength, and microstructure. This paper is a part of the research being conducted to evaluate the impact of four FSW techniques (bobbin, top-sided, bottom-sided, and doublesided) on the mechanical properties in dissimilar thick joints (12.7 mm) of aluminum alloys (AA7181-T7651 and AA7475- T7351) used in the aeronautics industry. The residual stresses were measured using the incremental blind hole technique and analyzed using the integral method. The longitudinal residual stresses were all positive, with values between 100 and 200 MPa in the stir zone, whereas the transverse ones were all negative, with values between 0 and − 100 MPa. It was possible to verify that the Bobbin process produced lower values of residual stresses and demonstrated better stability in its distribution compared to all the other FSW methods tested.