Materials Testing Volume 57 Issue 9

Materials Testing

Volume 57 Issue 9

Contents
Journal Overview

Adhesive tensile testing of atmospheric plasma sprayed zinc coating on a 1.4301 substrate

Philipp Stögmüller, Andreas Hinterer, Friedrich Pesendorfer, Norbert Enzinger August 31, 2015

More Cite

Abstract

The atmospheric plasma spray (APS) process for applying thin coatings on substrates has a lot of different process parameters. To evaluate which parameters have the most significant influence on the adhesive strength, a design of experience (DoE) investigation was performed. The data for the DoE analyses were generated with an own designed adhesive tensile strength test device according to EN 13144. For these experiments, the two component epoxy HTK Ultra Bond 100 was used for loading the interface of APS zinc coated steel samples. To provide a highly repeatable test setup, a special gluing device was developed to cope with the requirements of the Ultra Bond 100. Although the DoE analysis showed the expected results, the pull-off test has some weaknesses, which are shown and discussed in the present paper.

Fatigue strength of nodular cast iron with regard to heavy-wall applications

Christoph Bleicher, Rainer Wagener, Heinz Kaufmann, Tobias Melz August 31, 2015

More Cite

Abstract

For a proper estimation of the fatigue life of a heavy-walled cast component made of nodular cast iron, sufficient knowledge regarding the cyclic properties of the material is necessary. Based on the material parameters at hand for component design, different fatigue analysis procedures can be used. Elastic and elastic-plastic approaches can be adopted, with the latter being reserved only for local approaches. The present publication summarizes the cyclic material parameters gained during a research project by extensive material tests under stress and strain controlled cyclic loading at different load ratios for three nodular cast iron grades. In addition to an improved knowledge of the cyclic material behavior, the notch, the size effects and the mean stress sensitivity were of special concern during the investigations in order to provide an entire overview of the tested materials and thus input information for both stress and strain based design approaches. Tests were performed for specimens taken from large cast blocks of the nodular cast iron grades EN-GJS-400-18U-LT and EN-GJS-450-18, both with ferritic matrices, and EN-GJS-700-2 with a pearlitic matrix. For some of these materials, mean stress sensitivities above 0.5 were obtained during the investigations. These values are not covered by the common standards, which calculate lower values for the mean stress sensitivity. Cyclic material parameters for stress and strain controlled tests are given in this paper as well as values for the size effect, based on the concept of the highly stressed volume. The effect of different specimen sizes could be shown not only by stress but also by strain controlled tests.

Mechanical and corrosion properties of friction stir welded joints of Al-Cu alloy 2219-T87

G. Srinivasa Rao, V. V. Subba Rao, S. R. Koteswara Rao August 31, 2015

More Cite

Abstract

In the present study, 8.1 mm thick AA 2219–T87 plates were joined by friction stir welding (FSW) process. Welds were characterized by using micro hardness survey, tensile testing, face bend, root bend tests, optical microscopy (OM), transmission electron microscopy (TEM) and salt fog test (ASTM B117) at different pH values and spraying times. Hardness survey across the joint revealed that weld nugget is the softest region and it is also found that tensile failure occurs in the nugget. Tensile testing of the transverse welded joints showed that high efficiency (> 75 %) joints could be produced. The friction stir welds subjected to the surface bend showed 1800 bend ductility, whereas in the critical root bend the cracks were initiated at a bend angle in the range of 30–40 0 . Transmission electron micrographs obtained from various regions of the weld indicated that almost all strengthening precipitates dissolved in the nugget region while partial dissolution of precipitates occurred in the thermomechanically affected zone and coarsening occurred in heat affected zone. However, the losses in hardness in the nugget due to dissolution of precipitates and the negation of work hardening by recrystallization were compensated to a large extent by the strengthening due to the grain refinement in the nugget, which explains the high joint efficiencies exhibited by these welds. It was observed that the welds possessed much better corrosion resistance in basic and neutral solution than in acidic solution. It was found that corrosion attack was greater in the base material than in weld metal at all pH values and spraying times. It has been concluded that friction stir welding has a significant effect on mechanical and corrosion properties of the welds.

The effect of using heat treated ulexite and cashew in automotive friction materials

İlker Sugözü, İbrahim Mutlu, Ahmet Keskin August 31, 2015

More Cite

Abstract

In this experimental study, the use of heat treated ulexite and cashew as a new material in brake pads was investigated. The change of friction coefficient, the temperature of friction surface and amount of wear were examined to assess the performance of these samples. Additionlly, microstructural characterizations of braking pads were carried out using scanning electron microscopy. The results showed that the heat treated samples containing ulexite and cashew have an important effect on friction stability and fade resistance. It can be concluded that heat treated ulexite and cashew can be used as friction materials in the automotive brake pads.

Residual stress relaxation in welded large components

Majid Farajian, Thomas Nitschke-Pagel August 31, 2015

More Cite

Abstract

Residual stress relaxation of butt-welded large components under cyclic mechanical loading was investigated. The experiments were carried out on different types of steel with yield strengths between 300 and 800 MPa. X-ray diffraction technique was applied for the residual stresses analysis. High tensile residual stresses as high as the yield strength could be measured in large components. However, a fraction of maximum residual stress accommodated in the weld bead centerline is available at the weld toe. Under four-point bending of the large scale weldments, a considerable relaxation of residual stresses in the weld and its vicinity was observed during the first loadings. This behavior could be observed regardless wether the weld was under tensile or compressive loading.

Variation regulation of the acoustic emission energy parameter during the failure process of granite under uniaxial compression

Chunlai Wang, Tiancai Bao, Hui Lu, Lu Liu, Zhijiang Lu, Weiqiang Li, Qiwei Yu August 31, 2015

More Cite

Abstract

The AE energy characteristics of granite specimens were tested experimentally under uniaxial compression to investigate the variation regulation of acoustic emission (AE) energy during the granite failure process. The results show that the AE energy accompanies rock deformation and failure during the entire loading process. With stress increase, AE energy of granite specimens is in dynamic variation. There is a fine corresponding relationship between AE energy and stress. Under low stress levels, AE energy is relative low and remains stable. As stress increases, in the plastic deformation stage, AE energy rapidly increases and remains at a high level indicating intense energy which is released before rock failure. This phenomenon could be considered as the precursor for rock failure. Moreover, the corresponding time point where the AE energy release rate reaches the maximum is determined as the critical point for predicting rock failure. Then AE energy sharply decreases in the failure stage and rock instability occurs.

Iznik tiles: A new production technology and respective characterization

Meryem Sarigüzel, Şenol Yilmaz, Esin Günay August 31, 2015

More Cite

Abstract

This study investigated a new production technology for Iznik tiles. High quartz content of Iznik tiles was kept as it was and hydraulic pressing instead of tapping was used for shaping. Besides the traditional pouring technique, tiles were also glazed by spray coating. Characterization of the Iznik tiles were approached using different methodologies, including scanning electron microscopy plus energy dispersive X-ray spectrometry (SEM-EDX), Raman spectroscopy, atomic force microscopy (AFM), X-ray diffractometry (XRD) and dilatometry. Characterization results revealed that thermal expansion coefficients (TECs) of body, slip layer (thinned siliceous clay) and frit are 8.41, 8.48 and 8.32 × 10 −6 K −1 , respectively, and matched which is fundamental to achieve increase in strength and keep the glaze in compressive stress. Raman signatures of the Iznik tiles agreed with the literature information. By double layer spray coating, smoother surfaces can be obtained on Iznik tiles than by traditional method of glazing.

Quality during milling of a glass fiber reinforced polymer composite

Alper Uysal, Mihrigul Altan August 31, 2015

More Cite

Abstract

Glass fiber reinforced polymer composites are used as different structural components and machining processes are generally performed to fixing and assembling operations. Milling is one of them used in reaching the final dimensions and shapes of these composites. In this study, glass fiber reinforced polymer composite plates were milled under different cutting parameters such as depth of cut, feed and cutting speed. High speed steel and tungsten carbide cutting tools were used in the experiments. Relation between cutting parameters with surface roughness were investigated in details. Design of experiment was also used to determine the optimal cutting condition for minimum surface roughness. Analysis of variance was applied to determine the effectiveness of the parameters. Finally, cutting performance of the fibers along the edges of the milled surfaces was investigated according to selection of the tool and milling conditions.

Effect of abrasive water jet turning process parameters on surface roughness and material removal rate of AISI 1050 steel

Fuat Kartal, Hasan Gökkaya August 31, 2015

More Cite

Abstract

The purpose of this study was to optimize and determine the most important abrasive water jet turning (AWJT) operational parameters, such as nozzle diameter (0.75 and 1.3 mm), nozzle feed rate (5, 25 and 45min −1 ), stand-off distance (2, 10 and 18 mm), abrasive flow rate (50, 150 and 350 g × min −1 ), and spindle speed (500, 1500 and 2500 min −1 ), regarding machining efficiency parameters, namely, average surface roughness R a (µm) and material removal rate (mm 3 × min −1 ), using AISI 1050 steel workpieces machined by abrasive water jet turning. Taguchi L 18 (2 1 × 3 4 ) orthogonal experimental design was used for the experimental design. Adequacy of the predicted linear regression model equations was tested using the method of ANOVA. These model equations were used to optimize the operational parameters of the surface roughness and material removal rate. Machinability charts, indicating the optimum processes with respect to the surface roughness and material removal rate for AISI 1050 steel workpieces, were developed and presented in this study. As a result of experimental studies, it is seen that nozzle feed rate proved to have the most significant impact on surface roughness by 48.7 %. Abrasive flow rate proved to have the most significant impact on material removal rate by 84.6 %. Using a nozzle diameter of 0.75 mm, the average surface roughness was improved while material removal rate decreased.

Influence of cutting parameters on the chip-tool interface temperature during the turning of Waspaloy

Yahya Isik, Abdil Kus, M. Cemal Cakir August 31, 2015

More Cite

Abstract

Waspaloy, as a nickel superalloy, is a difficult-to-machine material used for gas turbine engine components that require considerable strength and corrosion resistance at high operating temperatures. The machining of nickel-based alloys generates high temperatures at the cutting tool edge. This research investigated the relationship between cutting parameters and cutting temperature, using a remote temperature measurement method employing an infrared thermometer. In addition, the effects of cutting parameters on surface roughness were examined. Experiments were conducted on Waspaloy AMS5708 superalloy samples and a PVD TiAlN-TiN-coated WNVG 080404-IC907 carbide insert was used during the turning process. It was observed that the highest cutting speed and highest feed rate generated higher temperatures and higher surface roughness. Better surface roughness was obtained with the lowest feed rate, the highest cutting speed and the higher cutting depth. No cutting fluid was used in the experiments.

Effects of the thixocasting injection velocity on tensile properties of an A357 Al alloy

Melika Özer, Neşet Akar, Kadir Kocatepe, Mehmet Erdoğan August 31, 2015

More Cite

Abstract

In this study, the effects of injection velocity on tensile properties and hardness of A357 aluminum alloy produced by thixocasting process were investigated. For this purpose, feedstock produced by cooling slope process were first held at reheating temperature of 572 °C and then formed at injection velocities of 1, 1.5, 2 and 2.37 m × s −1 , respectively. In order to make comparisons, other specimens were produced by high pressure die casting method via melted metal at the casting temperature of 630 °C using same injection velocities. Tensile test and hardness measurements were conducted for all specimens. The best tensile test properties were obtained for the specimens produced by thixocasting process at injection velocity of 2.37 m × s −1 . For this specimens, the values of 0.2 % proof strength, tensile strength and total elongation were obtained as 89.9 MPa, 237.3 MPa and 20.7 %, respectively. Furthermore, its hardness were measured as 74 HV.

Solid mold investment casting – A replication process for open-cell foam metal production

Kerem Altug Guler August 31, 2015

More Cite

Abstract

Foam metals have always been an interesting material type because of their unique properties and various production techniques. In this study, solid mold investment casting process, which is one of the replication techniques, was used to produce open-cell aluminum foam specimens. Commercial rubber sponge was tested as foam pattern material. Plaster bonded solid molds were prepared in the stainless steel flasks and infiltration of the slurry into the rubber sponge was carried out under vacuum. Following this, pattern removal and mold firing was carried out gradually. Molten A319 casting and A6063 wrought aluminum alloys were cast into flash molds with vacuum assistance (−10 5 Pa). Sponge pattern and cast foam specimens were examined and compared by stereo microscope and scanning electron microscope (SEM). It is clearly found that rubber sponge is a very suitable pattern material for producing open-cell foam structures.

Design of an impact testing machine for polymer films by the free falling dart procedure

Muhammad Musaddique Ali Rafique August 31, 2015

More Cite

Abstract

Impact forces have been used to study the behavior of materials for a long time. The aim of the impact testing is to investigate those conditions under which a material will fail in a brittle manner regarding a sudden load. There are three general methods of testing impact resistance of components: falling weight tests, pendulum tests and tumbling impact tests. In the present study, an attempt has been made to establish an impact tester used to carry out impact testing of plastic films by free falling dart method. In this, a box of wood with a hole on its upper side is used on which plastic film is held by clamps and a dart is allowed to fall onto film to note perforation. Then the impact resistance is statistically calculated. Impact resistance is determined by the energy caused by weight to fail 50 % of specimen. Practical results are found to be in good agreement with theory.

Mechanical and electrical properties of Sb-Ga50Au10In40 alloys

Lidija Gomidželović, Dragana Živković, Emina Požega, Vladan Ćosović, Ljubiša Balanović, Dragan Manasijević August 31, 2015

More Cite

Abstract

In this publication, results are presented which have been obtained by investigation of mechanical and electrical properties of alloys belonging to Sb-Ga50Au10In40 section of quaternary Au-Ga-In-Sb system, which is the basis for the development of new lead-free solder materials. The experiments were conducted using Brinell method for hardness measurement, apparatus PTM-3 for microhardness measurement and instrument Foerster SIGMATEST 2.069 for measuring of electrical conductivity. The microstructure of samples was analyzed using optical microscopy.

CFD simulation of particulate flow in a spiral concentrator

Gamal M. A. Mahran, Mohamed A. Doheim, Mohamed H. Abu-Ali, Ahmed F. Abdel August 31, 2015

More Cite

Abstract

A spiral concentrator is a gravity concentration device. It was invented by Humphreys in 1941. Firstly, it was designed and developed based on experience and by extensive testing of prototypes and modifications. The main objective of the present study is the simulation of the particulate flow of more realistic solid concentrations (i. e., 15 wt.-% solids) in a spiral separator. This study is based on the Eulerian approach and renormalization group k-∊ turbulence modeling. The results focus on particulate flow characteristics such as velocity, distribution and concentration of particulates on the spiral trough. The predicted results were compared with the experimental results in case of LD9 coal spiral. Comparisons between numerical and measured data showed good agreement.

About this journal

Materials Testing is a SCI-listed English language journal dealing with all aspects of material and component testing with a special focus on transfer between laboratory research into industrial application. The journal provides first-hand information on non-destructive, destructive, optical, physical and chemical test procedures. It contains exclusive articles which are peer-reviewed applying respectively high international quality criterions.
All articles are subject to thorough, independent peer review.

Editing Associations: DGZfP, DVM and VDI Materials Engineering.