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1

Study on narrow gap welding of martensitic grade P92 and austenitic grade AISI 304L SS steel for ultra-supercritical power plant application

Dak Gaurav, Khanna Navneet, Pandey Chandan

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e14, 2023

EN

The present work investigated the microstructural feature, mechanical properties, and residual stress variation for the dissimilar welded joints (DWJs) of P92 and AISI 304L steel. The multi-pass DWJs were attempted for narrow gap geometry using the tungsten inert gas (TIG) welding process employing the ERNiCrMo-3 filler metal. The martensitic microstructure produced in the P92 HAZ region after welding is brittle due to quenched martensite and the dissolution of precipitates. Thus, the post-weld heat treatment (PWHT) known as tempering was carried out at 760 °C for a period of 2 h to get tempered martensitic microstructure and re-precipitation of dissolved precipitates. The radiographic examination and macrostructure analysis showed defect-free P92/304L SS DWJs. The weld metal showed the complete austenitic microstructure with a Ni weight percentage of 36%. However, segregation of the alloying elements along with the inter-dendritic areas and variation in grain growth during solidification was observed. There is columnar grain morphology at interface, cellular, and equiaxed in the center. The major segregation along the inter-dendritic areas was observed for Nb, Mo, Ti, and Cr that led to the formation of the carbides of type Mo6C, TiC, and NbC, which was confirmed from the energy dispersive spectroscopy (EDS) analysis. From the tensile test result, 304L SS base metal (BM) was inferred as the weakest region in P92/304L SS DWJs. The ultimate tensile strength (UTS) of the as-weld joint was about 626 MPa, along with fracture location in 304L SS base metal. The Charpy impact test results showed that the region with relatively poor impact toughness was austenitic ERNiCrMo-3 filler weld (57 J) which might be due to the segregation of the Nb and Mo along the inter-dendritic areas. However, the impact toughness of the ERNiCrMo-3 filler weld met the minimum requirement of 47J (EN ISO 3580:2017). The micro-hardness result showed that in the as-welded condition, the coarse grain heat affected zone (CGHAZ) has the highest micro-hardness value (340 HV) due to the high weight percentage of Cr and N resulting from the dissolution of M23C6 precipitates followed by the fine grain heat affected zone (FGHAZ, 270 HV), and the inter-critical heat affected zone (ICHAZ, 205 HV). After PWHT, the hardness value was decreased below the maximum allowable value of 265 HV due to the tempering of the martensite. The residual stresses developed in the case of the narrow groove design were less due to the less quantity of weld metal available for volumetric contraction in the case of the narrow groove geometry. The tensile stress was dominant in the weld fusion zone due to the volumetric contraction of the weld metal, while compressive stress was dominant in P92 HAZ because of the martensitic phase transformation.

2

Residual stresses evolution and process route optimization of TC4 profiled rolled rings incorporating thermal bulging

Lv Nan, Liu Dong, Wang Jianguo, Rao Haodong, Nan Jungang

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e200, 2023

EN

The thermal processing of rolled rings inevitably generates and accumulates massive residual stresses, as quenching residual stresses produced by water cooling treatment. Non-uniformly distributed residual stresses would seriously affect the structural strength, dimensional stability and service life of the component. In the traditional rolling process of titanium alloy rings, the quenching residual compressive stresses introduced by solution treatment could reach – 400–600 MPa, for which effective control of the stresses is an urgent issue to be solved. In this research, the stress control efficiency of rolling rings under different process routes was explored according to the thermal bulge stress relief technique. The FEM model of the stress evolution in the whole process of the rolled ring was established. The residual stresses on the ring surface are characterized by the hole-drilling method, while the microstructures are characterized by electron backscatter diffraction. The results indicated that the optimized process incorporating the thermal bulging stress relief technique reduced the levels of stress values to within about ± 50 MP and the stress homogenization index by approximately 60–90%.

3

Kumar Amit, Pandey Shailesh M., Pandey Chandan

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e54, 2023

EN

A dissimilar joint of martensitic grade P92 and Ni-based Inconel 617 (IN617) alloy are employed commonly in advanced ultra-supercritical (AUSC) units to fabricate thick section components such as steam pipes and turbine rotors. This study investigated the weldability of the IN617 alloy and P92 steel dissimilar welds. Ni-based superalloy ERNiCrMo-3 filler was used to attempt the dissimilar joining for conventional V groove and narrow groove design by employing the gas tungsten arc welding (GTAW) process. The weld metal for the capping pass, backing pass, and near the interface showed the columnar and cellular grains while equiaxed grains are observed corresponding to root and filling passes. The energy dispersive spectroscopy and Electron probe micro-analyzer (EMPA) study confirmed the segregation of the Nb and Mo particles in inter-dendritic spaces and resulted in the formation of the Nb-rich NbC and laves phases and Mo-rich phases. The EDS line map and EPMA study of the P92 interface showed a sharp increase in Cr, Mo, and Ni concentration and a steep decrease in Fe concentration as moving from P92 base metal to weld metal. A negligible diffusion from filler weld to IN617 or vice versa across the IN617 interface was detected. The microhardness gradient along the weldments indicated a sharp rise in hardness value near the P92 fusion boundary due to the formation of the unmixed zone of lower hardness and the P92 coarse-grained heat-affected zone of higher hardness. The weld metal hardness results showed a great variation with an average hardness value for V groove and narrow groove welds of 227 and 262 HV, respectively. The mechanical tests were conducted at the ambient temperatures and data obtained for the weldments were compared with the base metals. The room temperature tensile tests showed the failure from the region of the P92 BM or the interface of P92 BM/weld metal, with joint strength of 646 ± 6 MPa and 747 ± 4 MPa in AW conditions for V groove and narrow groove, respectively. The Charpy impact test (CIT) also showed the variation in impact toughness along the weldments, and the ERNiCrMo-3 filler weld was identified as the weakest region of the welded joint in terms of impact toughness for both the groove designs. The residual stress variation along the thickness of the weld plate was measured using the deep hole drilling (DHT) methods, and the results indicated the peak magnitude of the residual stress for the V groove welded joint. The test results indicated that welded joint produced using ERNiCrMo-3 filler was safe for AUSC power plants' boiler applications for both the groove weld while optimum mechanical properties were measured for narrow groove weld.

4

Effect of simulated axial residual stress and transverse residual stress in welded P92 pipe and plates including plasticity error

Pal Vinay Kumar, Singh Lokendra Pal

Journal of Mechanical and Energy Engineering

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2022

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Vol. 6, No 2

1--18

EN

The paper deals with the measurement of residual stresses in P92 welded pipe using the blind hole drilling technique. The post weld heat treatment (PWHT) of a P92 welded pipe was also conducted to study their effect on residual stresses. The P92 pipe weld joints were prepared using gas tungsten arc welding process. The residual stress measurement was carried out using a strain gauge rosette that was associated with the plastic deformation of the material and a stress concentration effect of a multi-point cutting tool. A corrective formulation was developed for calculating the corrected value of residual stresses from the experimentally obtained strain value. The Strain gauge response was estimated experimentally using tensile testing for uniaxial loading while a finite element analysis was performed for biaxial loading. A gas tungsten arc welds joint was prepared for a conventional V-groove and a narrow groove design.

5

The influence of workpiece speed on microhardness and residual stresses in vacuum-carburised 20MnCr5 steel using the single-piece flow method

Sawicki J., Januszewicz B., Sikora M., Witkowski B.

Archives of Materials Science and Engineering

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2022

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Vol. 115, nr 2

66--75

EN

Purpose: To determine the impact of selected conditions of abrasive treatment on the value and distribution of microhardness and residual stresses in layers carburised by a continuous single-piece flow method. Design/methodology/approach: Reference pieces were low pressure carburised at 920°C and then heat-treated in a 4D Quench heat treatment chamber at a pressure of 7 bar and tempered at 190ºC for 3 hours. In the next stage, samples were ground at various vw piece speeds, introducing grinding fluid into the cutting zone using the WET spraying method or using the MQL method at a minimum flow rate. The distribution of microhardness and residual stresses generated in the technological outer layer of the pieces following heat and chemical treatment and the grinding process was measured. Findings: Results of the tests indicated that the vw piece speed and method used to supply cooling and lubricating fluid to the grinding zone had an impact on selected parameters of the technological outer layer of flat samples made of 20MnCr5 steel. The process of grinding using an electrocorundum grinding wheel results in a deterioration of residual stresses in the material. For each of the three analysed vw piece speeds, reduced changes in material microhardness prior to cutting occur in the outer layer of samples ground using GF supplied at a minimum flow rate using the MQL method. Research limitations/implications: Environmental considerations and having to conform to increasingly stringent regulations related to environmental protection and employee safety motivate researchers and businesses to entirely eliminate or reduce the use of grinding fluids in the grinding process and, therefore, to optimise grinding technology. Practical implications: Modern manufacturing industry requires the grinding process, which follows heat and chemical treatment, to be performed with the highest possible efficiency. However, retaining high parameters of the technological outer layer in comparison to the sample material following vacuum carburisation (before grinding) is extremely difficult. An optimised configuration of parameters of the grinding process and method of supplying grinding fluids enables meeting the current and future high expectations of the industry in this regard. Originality/value: The tests have enabled us to determine the impact of the applied vw workpiece speed and method of supplying grinding fluid on microhardness and residual stresses. Generally speaking, grinding with an electrocorundum grinding wheel results in a deterioration of residual stresses. For both methods of supplying GF (WET and MQL), the distribution of microhardness in the material of the samples ground with the highest workpiece speed (18.0 m/min) indicated no significant differences with regard to the distribution of microhardness in the material of the samples following heat and chemical treatment.

6

Finite element analysis of thermal stress in Cu2O coating synthesized on Cu substrate

Shorinov O.

Archives of Materials Science and Engineering

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2022

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Vol. 115, nr 2

58--65

EN

Purpose: The paper aims to find the magnitude and nature of thermal residual stresses that occur during cooling of a copper sample with a thermally synthesized oxide layer of Cu2O. Design/methodology/approach: Thermo-mechanical analysis was performed by the finite element method using Ansys Software. The results of thermal analysis were used to study the resulting stress-strain state of the thin film/coating system after cooling. Findings: Based on the modeling results, the paper determined the most stress-strain areas of the sample with a coating, which are the free edges of the interfaces between the copper substrate and the Cu2O oxide layer. Research limitations/implications: The main limitations of the study are the use of certain simplifications in the condition setup, for instance, uniform cooling of the thin film/coating system, homogeneity and isotropy of substrate and thin film materials, invariance of their properties with temperature changes, etc. Practical implications: The results obtained can be used to control the stress-strain state of the thin film/coating system and prevent deformations and destruction of thin-film structures during their production and operation of products with them. Originality/value: The study of new promising methods for the formation of oxide nanostructures, for instance in a plasma environment, requires a sufficient theoretical basis in addressing the origin and development of stresses.

7

Study on effect of weld groove geometry on mechanical behavior and residual stresses variation in dissimilar welds of P92/SS304L steel for USC boilers

Dak Gaurav, Pandey Chandan

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 3

art. no. e140

EN

This research article reports the correlation between microstructure, mechanical properties, and residual stresses of dissimilar weld joints (DWJs) between P92 martensitic steel and 304L austenitic stainless steel (ASS). The groove geometry plays a vital role in DWJs. Thus the effect of groove geometry on mechanical and microstructural properties was also investigated. The V-shape and narrow shape groove profile were implemented for P92/304L SS DWJs. The microstructural characteristic, tensile strength, micro-hardness, Charpy impact toughness and residual stresses were evaluated for both the groove geometry in as-weld (AW) and post-weld heat treatment (PWHT) (760 °C, 2 h) state. Microstructural observations performed using an optical microscope (OM), and scanning electron microscope (SEM) showed that high temperature during the weld thermal cycle leads to the formation of the coarse grain heat-affected zone (CGHAZ), fine grain HAZ (FGHAZ), and inter-critical HAZ (ICHAZ) across the P92 HAZ. The ERNiFeCr-2 (Inconel 718) welding consumable wire (filler rod) of diameter 2.4 mm was used for this investigation. The ERNiFeCr-2 weld fusion zone showed a fully austenitic microstructure with the formation of the secondary phases due to the solidification segregation. The EDS and SEM area mapping results indicated that the secondary phases in the inter-dendritic region contain a higher amount of the Mo and Nb than the matrix region. The ultimate tensile strength (UTS) of the as-weld and PWHT tensile specimen of the P92/304L SS DWJs was 630 and 621 MPa, respectively, for V-groove geometry specimens and 620 and 629 MPa, respectively, for narrow groove geometry specimens. The tensile fracture was experienced at the interface between weld metal and 304L base metal, and the UTS value of DWJs was very close to the UTS of the 304L SS. The abrupt variation in the micro-hardness value of the CGHAZ (456HV0.5), FGHAZ (375HV0.5), and ICHAZ (221HV0.5) was noticed in the as-weld state due to their distinguish microstructure characteristics. After PWHT, the micro-hardness value of the CGHAZ (255HV0.5), FGHAZ (236HV0.5), and ICHAZ (207HV0.5) was below the maximum allowable value of 265HV0.5 for P92 material because of the tempering of the martensite. The Charpy impact test indicated that the ERNiFeCr-2 weld fusion zone has a low toughness value of 33 J (AW) and 25 J (PWHT) for V-groove design and 35 J (AW) and 28 J (PWHT) for narrow groove design than that of the P92 and 304L parent metal. The impact toughness of the ERNiFeCr-2 filler weld was below the minimum requirement of 47 J (EN ISO 3580:2017). The tensile residual stresses were generated in the weld fusion zone due to the volumetric contraction during the solidification. The residual stresses developed in the case of the narrow groove design were less than that for the V-groove design due to the less quantity of weld metal available for volumetric contraction in the case of the narrow groove geometry. From comparing mechanical and microstructural properties obtained for V-groove and narrow groove geometry DWJs, it was found that narrow groove design reduces the overall heat affected zone span, and it requires less welding time and less heat input.

8

A new method for measurement the residual stresses in friction stir welding

Jweeg M.J., Hamdan Z.Kh., Majeed A.H., Resan K.K., Al-Waily M.

Archives of Materials Science and Engineering

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2021

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Vol. 112, nr 2

63--69

EN

Purpose: The residual stresses in different welding methods are fundemental problems to consider. Friction stir welding is one of a solid state joining process, it is economical in that it permits joining together different materials, the specimens in this method (FSW) have excellent properties of mechanical as proven by tensile, flextural and fatigue tests, also it is environmentally friendly process minimizes consumption of energy and generate no gasses or smoke. In friction stir welding , there are two kinds of generated residual stresses: tensile stress and compressive stress. So, this study measuring the residual stresses by using a new method for measuring residual stresses depends on tensile testing and stress concentration factor, this method is a simple, fast and low cost, also it is not need special device. Design/methodology/approach: In previous studies, several techniques were used to predict the value of residual stress and its location, such as destructive, semi-destructive, and non-destructive methods. In this study, a simple, new, and inexpensive way was used based on the tensile test and stress concentration of the friction stir welding (FSW). Findings: By comparing the results obtained with the previous studies using the X-ray method, with the current research, it was found that the results are good in detecting the location and value of the residual stress of friction stir welding. The value of discrepancy of the residual stress in the results between those obtained by the previous method and the current method was about 3 MPa. Research limitations/implications: There are many rotational and linear feeding speeds used in this type of welding. This research used two plates from 6061 AA with 3mm thickness, 100 mm width, and 200 mm length. The rotational speed used in friction stir welding was 1400 rpm, and the feeding speed was 40 mm/min. Practical implications: The residual stress obtained with the new method is 6.2 MPa, and this result approximates other known methods such as the X-ray method in previus studies. Originality/value: Using a new simple method for measuring residual stresses of friction stir welding depends on stress concentration factor and tensile testing. This method is fast and low cost , also it is not need specialized device, compared to other methods such as x-ray or hole drilling methods.

9

A theoretical analysis of vibrational stress relief in AISI 1008 as a mechanical treatment

Vardanjani Mehdi Jafari, Senkara Jacek

Archive of Mechanical Engineering

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2021

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LXVIII, nr 4

353--374

EN

Vibrational stress relief (VSR) treatment as a method of stress relief is currently performed on different alloys and sizes as an appropriate alternative for thermal stress relief (TSR) method. Although many studies have been performed to extend the knowledge about this process, analytical studies in the field of VSR process seems to require wider efforts to introduce the concept more clearly and extensively. In this study, a theoretical model is proposed based on an analytical equation. The proposed equation was modified in terms of required variables including frequency, amplitude, and vibration duration to encompass more practical parameters compared to the previous models. Thus, essential VSR parameters including the number of cycles as a representative of treatment duration, strain rate as a representative of frequency, and the amplitude were embedded in the model to make it comprehensively practical. Experimental tests were also performed and residual stress distribution was measured by X-ray diffractometry (XRD) method for certain points to compare the experimental results with the theoretical output. An acceptable range of conformation was observed between theoretical and experimental results.

10

Wpływ rozkładu naprężeń szczątkowych na badania wytrzymałościowe

Neugebauer Jürgen, Kasumovic Irma, Blazevic Ivo

Świat Szkła

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2019

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R. 24, nr 6

34--37

11

Relief of residual stress in Al2O3/Nb joints brazed with Ag-Cu-Ti/Cu/Ag-Cu-Ti composite interlayer

Zhao Yating, Wang Ying, Yang Zhenwen, Wang Dongpo

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 1

1--10

EN

Ag-Cu-Ti/Cu/Ag-Cu-Ti composite interlayer was successfully designed to braze Al2O3 ceramic and Nb. The effect of the addition of Cu interlayer with various thicknesses on the microstructure, residual stress and mechanical properties of the brazed joints was investigated by finite element modeling (FEM) computation combined with experimental verification. The results showed that the layered Ag-Cu-Ag solid solution structure formed in the Al2O3/Nb brazed joints when the composite interlayer was used. Moreover, the thickness of TiO + Ti3Cu3O reaction layers adjacent to the Al2O3 ceramic substrate did not change obviously regardless of the Cu foil thickness. The maximum residual stress in the whole brazed joint always appeared in the Al2O3 ceramic substrate nearby the interlayer, but it was reduced from 384 MPa to 119 MPa when a 150 μm thick Cu foil was added. The variation of calculated residual stresses as a function of Cu foil thickness, which was verified by X-ray measurement, exhibited a consistent with Al2O3 ceramic strain energy. Thus, the calculation of Al2O3 ceramic strain energy could be a good criterion to evaluate the joint shear strength because the fracture occurred in the Al2O3 ceramic. The reduction of detrimental residual stress was primarily attributed to the increased plastic strain energy of Cu interlayer. The FEM and experiment results indicated that the ability of plastic deformation of the interlayer played a key role in determining the residual stress in the brazed joint, providing a method for improving the bonding properties of ceramic and metal.

12

Formability and forming of welded semi-finished parts from corrosion resistant steel

Bilik J., Sugarova J., Kusy M., Tittel V.

Hutnik, Wiadomości Hutnicze

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2017

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Vol. 84, nr 8

359--363

EN

The paper is focused on study of formability of welded semi-finished parts from SAF 2507 corrosion resistant steel. The formability is evaluated on the base of tensile test and Erichsen cup test of test samples without weld and welded test samples. The paper mentions also the results of cup test for determination of maximum drawing ratio and results of drawn parts residual stress measurements.

PL

Niniejszy artykuł opisuje badania odkształcalności spawanych półfabrykatów ze stali odpornej na korozję SAF 2507. Odkształcalność była oceniana na podstawie próby rozciągania oraz próby tłoczności wg. Erichsena – oceniano zarówno próbki bez spawu oraz próbki spawane. Praca prezentuje wyniki próby tłoczenia w celu ustalenia maksymalnego współczynnika ciągnienia oraz wyniki pomiarów naprężenia szczątkowego elementów ciągnionych.

13

Modeling of burnishing thermally toughened X42CrMo4 steel with a ceramic ZrO2 ball

Grochała D., Berczyński S., Grządziel Z.

Archives of Civil and Mechanical Engineering

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2017

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Vol. 17, no. 4

1011--1018

EN

Modeling of burnishing steel objects made of X42CrMo4 steel with a ceramic ZrO2 ball has been a substantial part of research into modeling of burnishing operations. The industrial sector has shown much attention to burnishing injection molds, matrices and press tools. When combined with milling, burnishing is able to produce very good parameters of surface roughness [1–6]. Some authors [2–5] demonstrated a close link between roughness parameters after burnishing and the surface shape obtained after milling. The synergy effect of combined milling and burnishing and its parameter identification issues were discussed at length in [2]. In most cases [1–6], the optimal technological parameters of machining operations are determined in experimental investigations. The present paper shows the method of developing and validating an FEM model. It can be used to identify the effect of milling and burnishing parameters on stress in the surface layer and plastic deformations of surface geometry of the work piece without having to conduct expensive and time-consuming experiments. The model can be used to preselect machining parameters to produce injection molds, matrices and press tools.

14

Application of 3D DIC Displacement Field Measurement in Residual Stress Calculations

Brynk T.

Advances in Materials Science

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2017

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Vol. 17, nr 3(53)

46--53

EN

The knowledge of residual stress distribution is of great importance from the viewpoint of both, industrial and basal research. The most commonly utilized method of residual stress determination is based on strain measurements near the drilled holes of known geometry made by means of tensometric rosettes. An alternative to tensometers way of strain measurement is Digital Image Correlation (DIC). This optical method utilizes digital images registered during observed object deformation and delivers results in the form of displacement field maps consisting of hundreds or thousands of data points. Therefore, it is possible to deliver much more data in comparison to rosettes (only 3 or 6 tensometers, usually) and use them in the inverse method numeric procedure for residual stress calculations. In the paper the experimental stand consisting of micro driller and stereo imaging system for 3D DIC measurement and its application to residual stress estimation in prestrained steel samples are presented followed by obtained results discussion.

15

Three-dimensional modelling of thermal stresses in a planar solid oxide fuel cell of a novel design

Zinko T., Pianko-Oprych P., Jaworski Z.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2016

|

nr 1

69--72

EN

The presented modelling investigation was carried out to analyze thermal stresses and expansion in an anode supported planar Solid Oxide Fuel Cell (pSOFC). The temperature distribution was based on previously developed thermo-electrochemical model predicting fuel cell operation. The design of a single pSOFC consisted of three ceramic layers of membrane electrode assembly: anode, electrolyte, cathode and two cross-flow bipolar plates with 26 ribs. The gases flowed diagonally from one cell corner to the opposite one. The fuel and air flows were cross-wise opposed on each bipolar plate side. The study allowed to indicate the most vulnerable to thermal damage area of the fuel cell in the operating conditions. The results will be useful in further design modification and performance optimization of the SOFC.

PL

Przeprowadzone symulacje numeryczne miały na celu analizę termicznych naprężeń i ocenę stopnia wydłużenia płaskiego stałotlenkowego ogniwa paliwowego typu pSOFC (ang. planar Solid Oxide Fuel Cell). Rozkład temperatury w ogniwie wyznaczono w oparciu o wcześniej opracowany model termiczno-elektrochemiczny [11]. Nowatorskie rozwiązanie ogniwa typu pSOFC objęło ceramiczną konstrukcję, w skład której weszły porowate elektrody – anoda i katoda, elektrolit oraz dwie płytki bipolarne z 26-cioma żebrami. Przepływ paliwa i powietrza odbywał się krzyżowo i przeciwprądowo, po przekątnej ogniwa. Wyniki symulacji pozwoliły na określenie obszarów ogniwa narażonych na uszkodzenie w wyniku wysokich wartości naprężeń termicznych. Uzyskane rezultaty FEM umożliwią dalszą modyfikację konstrukcji płaskiego ogniwa w celu optymalizacji wydajności pSOFC.

16

The effect of process parameters on residual stress in a friction stir processed cast aluminium alloy AlSi9Mg

Węglowski M. S., Sędek P., Hamilton C.

Engineering Transactions

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2016

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Vol. 64, iss. 3

301--309

EN

The effect of friction stir processing (FSP) on residual stress in a modified cast aluminium alloy AlSi9Mg is presented. The influence of rotational speed and tool type were analysed. The trepanation method was utilized to experimentally measure the residual stress. The results indicate that an increase in rotational speed causes an increase in residual stress. The region around the FSP bead was characterised by tensile residual stress fields which were balanced by compressive stresses in the parent material. A higher residual stress was observed on the advancing side than on the retreating side. Moreover, this asymmetry in residual stress distribution is due to the asymmetry in the volume of material plasticized along the advancing and retreating sides of the stir zone, generating the observed heat distribution. A higher level of residual stress was achieved with the Triflute tool than with a conventional tool.

17

The influence of product thickness on the measurements by Barkhausen Noise method

Garstka T.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 27, nr 1

47-50

EN

Purpose: The aim of this paper is to show how varying cross section thickness of tested product and calibration sample can depend on results of the residual stress measurements by the Barkhausen Noise method. Design/methodology/approach: The Barkhausen noise parameters as RMS value and total number of Barkhausen pulses in samples with different thickness was measured and compared. Also influence of the frequency and intensity of the magnetization current was analysing. Findings: The significant indirect influence of various cross-section thicknesses on Barkhausen Noise level was pointed. The equations describing influence of the thickness on Barkhausen noise at different magnetization current parameters were found. Research limitations/implications: Also the influence of the differences in width of the calibration sample and tested product was observed but in this research was not analysed. Practical implications: Taking into consideration obtained results lets compensate analytically indirect influence of geometrical factors and magnetization parameters on Barkhausen noise parameters. Originality/value: Original value of this paper is demonstrating significant source of error during residual stress measurements by Barkhausen method. For this moment this fact were not taken into consideration.

18

Contact interaction of resilient and cylindrical dies with initial (residual) tension

Yaretska N.

Czasopismo Techniczne. Mechanika

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2008

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R. 105, z. 3-M

213-216

EN

The article deals with a mixed type task of measuring pressure of an elastic cylinder die upon a layer with initial stresses within the framework of linear elasticity theory. In general, the research was carried out for the theory of great initial (ultimate) deformations and different variants of the theory of small initial deformations with arbitrary structure of elastic potential.

PL

W artykule podjęto zagadnienie pomiaru ciśnienia w elastycznej formie cylindrycznej w obecności wstępnych naprężeń, wykorzystując teorię sprężystości. Ogólnie, badania były prowadzone na podstawie teorii dużych odkształceń początkowych oraz różnych wariantów teorii małych odkształceń początkowych przy dowolnej wartości potencjału sprężystości.

19

Spawanie metodą TIG-mikropuls cienkich blach ze stali austenitycznej

Surowska B., Brudkiewicz D.

Przegląd Spawalnictwa

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2006

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R. 78, nr 5-6

53-56

PL

Nowoczesne technologie spawalnicze umożliwiają sterowanie procesem topienia i krystalizacji spoiny poprzez sterowanie przebiegiem amplitudy natężenia prądu w metodzie TIG. Zastosowanie mikropulsacji prądu poszerza zakres stosowania metody TIG na elementy cienkościenne i o małych gabarytach. Wykonano serię złączy doczołowych z blachy ze stali austenitycznej o grubości 1 mm metodą TIG-mikropuls, zmieniając parametry tak, żeby uzyskać częstotliwość z przedziału od 5 Hz do ponad 300 Hz. Oceniano wpływ tych parametrów na strukturę spoiny, strefę wpływu ciepła oraz naprężenia. Otrzymane wyniki porównywano do osiąganych przy spawaniu metodami TIG-puls oraz stałoprądową TIG na takim samym materiale. Skuteczność metody spawalniczej sprawdzono w warunkach przemysłowych, wykonując połączenia spawane dennic płaszczowo-rurowych wymienników ciepła. Przy wysokich częstotliwościach otrzymano złącza o korzystnej strukturze ferrytyczno--austenitycznej z dendrytami wydłużonymi. Rozciągające naprężenia resztkowe w obszarze spoiny i strefy wpływu ciepła nie przekraczały wartości granicy plastyczności. Zaobserwowano zależność właściwości wytrzymałościowych od liniowej energii spawania oraz częstotliwości. Za najkorzystniejszą ze względu na właściwości wytrzymałościowe uznano energię ok. 70 J/mm.

EN

The TIG-micropulse is a modern method of welding with kHz level frequency. Due to the reduced amount of heat delivered to the weld it is possible to achieve advantageous mechanical qualities of welding joints and decrease welding stresses. The butt joints of 1 mm austenitic sheet type X5CrNi18-10 were carried out by TIG-micropulse method. These welding joints structure and properties were compared with TIG-pulse and TIG-DC joints. The quantitative analysis of Fe-Alfa phase in welded joint and in heat-affected zone (HAZ) was carried out by X-ray diffraction method. The tensile strength as well as microhardness tests have been conducted. The strength test constituted the basis for deve!oping thinwalled elements welding parameters optimization depending on welding linear energy as well as current impulses freguency. The residual stress test was carried out using X-ray diffraction method. It was found that the residual stresses are decreased with increase in welding current impulses freguency. It was proved that a relation between welding linear energy and the qualities of austenitic steel joints strength does exist.

20

Superficial integrity analysis in a super duplex stainless steel after turning

Bordinassi E. C., Stipkovic M. F., Batalha G. F., Delijaicov S., Lima de N. B.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 18, nr 1-2

335--338

EN

Purpose: Purpose of this paper was to study the main effects of the turning in the superficial integrity of the duplex stainless steel ASTM A890-Gr6A. Design/methodology/approach: The focus of the work was the finishing operations and a complete factorial planning was used, with 2 levels and 5 factors. The tests were conducted on a turning center with carbide tools and the main entrances variables were: tool material class, feed rate, cutting depth, cutting speed and cutting fluid utilization. The answers analyzed were: micro structural analysis by optical microscopy and x-ray diffraction, cutting forces measurements by a piezoelectric dynamometer, surface roughness, residual stress by x-ray diffraction technique and the micro-hardness measurements. Findings: The results do not showed any changes in the micro structural of the material, even when the greater cutting parameters were used. All the other answers were correlated with the cutting parameters and its better combination was founded for the best superficial integrity. The smaller feed rate (0.1 mm/v), smaller cutting speed (110 m/min) and the greater cutting depth (0.5 mm) provided the smaller values for the tensile residua stress, the smaller surface roughness and the greater micro-hardness. Research limitations/implications: The correlation between all the answers was very difficult to analyze because there was great interaction between the factors, but for some data group it was possible. Originality/value: The paper contribute for the study of the super duplex stainless steel, considering that no one researches was founded for the studied topics in this material in witch presents different behavior in machining when compared with another stainless steels.