Impact Fracture Tests Research Articles

The Effect of the Incorporation of a 3D-Printed Titanium Framework on the Mechanical Properties CAD/CAM Denture Base Materials

Background: Complete dentures should withstand occlusal forces and wear. However, over time, dentures can suffer fatigue and develop cracks, chipping, and fractures. Conventional methods for the fabrication of complete dentures involve injection molding, thermal curing, and the use of microwaves with polymethyl methacrylate (PMMA)-based materials. These methods have served well for many years. More recently, the incorporation of computer-aided design and computer-aided manufacturing (CAD/CAM) to fabricate complete dentures has been shown to enhance the dentures’ mechanical properties, including resistance to wear and impact strength. This study aims to investigate the mechanical properties and fracture types of CAD/CAM denture base materials (both milled and printed) as compared to a novel proprietary method that embeds a 3D-printed framework within PMMA-milled blocks. The null hypothesis is that incorporating a 3D-printed framework does not affect the mechanical properties of milled PMMA blocks. Methods: Three groups of bars were fabricated using CAD/CAM methods: printed (P), milled (M), and milled with a 3D-printed metallic framework reinforcement (M + F). A three-point bending test evaluated deformation, followed by an impact fracture test for fracture toughness. A descriptive fractographic analysis assessed the fracture characteristics. A statistical analysis using a paired t-test compared the differences between the groups. Results: The P group showed more elastic deformation than the M and M + F groups (p < 0.05). The M + F group achieved a higher fracture toughness as compared to the M and P groups (p < 0.05). Conclusions: Within the limitations of this experimental study, the null hypothesis can be rejected. Milled samples with an embedded 3D-printed titanium framework possess higher resistance to impact than milled samples without frameworks, and printed samples and milled samples with embedded 3d-printed titanium frameworks present increased flexural strength and lower elastic deformation as compared to milled samples without frameworks and printed samples.

Processing–microstructure–fracture toughness relationships in PP/EPDM/SiO2 blend‐nanocomposites: Effect of mixing sequence

AbstractThis study investigates the mechanical properties and fracture behavior of polypropylene (PP)‐based blend‐nanocomposites comprising 30 wt.% ethylene–propylene–diene monomer (EPDM) and 5 wt.% SiO2 nanoparticles. Different mixing sequences were employed to prepare the nanocomposites, and the resulting morphology development and dispersion states of modifiers were analyzed. Mechanical performance of the nanocomposites was evaluated through quasi‐static and high‐speed dynamic fracture tests. The dispersion and distribution of SiO2 nanoparticles within the nanocomposites were significantly influenced by the mixing protocol. In impact fracture tests, the presence of nanoparticles exhibited a beneficial efffect on fracture energy, demonstrating a synergistic toughening effect of the soft EPDM and rigid SiO2 particles. Conversely, adverse effects were observed in quasi‐static tests. Essential work of fracture (EWF) parameters indicated an increase in the yielding component and a decrease in the necking‐to‐tearing component with SiO2 incorporation into the PP/EPDM blends. During impact loadings, the highest improvement in crack propagation resistance was observed in nanocomposites with nanoparticles localized around the rubbery domains forming a network‐like structure of EPDM/SiO2‐nanoparticles. Morphologies where rubber domains and nanoparticles were separately distributed in the PP matrix resulted in the lowest fracture parameters. Energy dissipation mechanisms were elucidated, revealing multiple void formation followed by matrix shear yielding as the primary source under both quasi‐static and impact fracture conditions. In the latter case, stress‐concentrating percolated structures in the PP matrix facilitated the nucleation of dilatational bands evolving into highly stretched void‐fibrillar structures upon further loading. These findings contribute valuable insights into tailoring nanocomposite morphologies for enhanced mechanical performance in different loading scenarios.Highlights Fracture behavior of PP/EPDM/SiO2 ternary systems was evaluated by EWF methodology and Izod impact test. Rubber particles surrounded by silica nanoparticles led to a percolated morphology and as a result to superior impact resistance. EWF parameters were mostly controlled by the tearing‐related parts regardless of phase morphology. The impact toughness was mainly controlled by the dispersion and distribution characteristics of the SiO2 nanoparticles.

Effect of stress relief and solubilization heat treatments on laser additive manufactured Inconel 625: microstructure and properties

This work assesses the effect of the energy input and the stress relief and solubilization heat treatment on the microstructure and mechanical properties of an Inconel 625 alloy processed by laser additive manufacturing using directed energy deposition. Two processing conditions were used to deliver high productivity with a high energy input (HEI) and another with better geometrical precision using a lower energy input (LEI). The mechanical test samples were built vertically and horizontally aligned with the tensile test direction. The samples were submitted to residual stress relief (SR) and SR + solubilization (S) heat treatments (SR + S). Results showed increased elongation with solubilization heat treatment, while UTS and YS decreased with heat treatment combination, which was linked to the stronger texture developed in HEI condition. Samples built in the vertical direction presented lower YS. The fracture toughness of solubilization heat-treated samples showed higher values, while LEI gave just slightly higher values. Although the microstructural and mechanical features are similar between the HEI and LEI conditions, the first stands out because parts can be fabricated quickly without losing mechanical performance under quasi-static conditions, impact fracture tests, or the production of unwanted phases.

Double vibratory stress relief treatment of welded pipes as an alternative to heat stress relief treatment: Effects on hardness, Charpy impact energy and CTOD

This work analyzes the effects of intermittent resonant vibration treatment in pipes welded to connectors applied in the field of oil and gas wells. The vibratory stress relief (VSR) process was applied intermittently under two conditions: the first one, called Simple Vibration Treatment (TVS), which consisted of a resonant vibration treatment with the vibrational system at the mean length of the product, a second step, with the product being rotated 90°. The results obtained with this process led us to study a new resonant vibration process with the purpose of intensifying the previous one, taking care that no defects would be introduced into the product. This condition, called Double Vibration Treatment (TVD), consisted of a treatment formed of three steps: the first two steps were performed in the same way and with the same procedure used in the Single Vibration Process (TVS). The third step consisted of carrying out a second resonant vibratory treatment with the vibrator positioned on the longitudinal weld of the pipe, close to the circumferential weld of the pipe with the connector. These VSR treatments were compared with the stress relief heat treatment PWHT (Post Weld Heat Treatment) which is normally used after welding the connectors to the pipe. The resonant vibration treatments (VSR), did not introducing any damage to the product, presented reduced treatment time, and tended to positively affect the evaluated mechanical properties, exceeding or equaling the same tendency presented by the heat treatment. The resonant Doble Vibration Treatment (TVD) showed the best results, affecting the evaluated properties more positively than the TVS, which practically promoted the same trend of results produced by PWHT. The studies were characterized by Vickers hardness tests, Charpy V impact fracture tests and CTOD fracture toughness tests, and the results were analyzed using ANOVA statistical modeling.

Effects of Mo alloying on the microstructure and wear resistance of Fe–B surfacing alloys

The effect of Mo addition on microstructure, impact property, and wear resistance of high boron Fe-4.5 wt% B surfacing alloy, which was developed by the three-arc double-wire welding method was investigated in this work. The phase structure and microstructure of the surfacing alloy were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and Electron Backscattered Diffraction (EBSD). Besides, a two-body abrasive wear test and impact fracture test was carried out to study the wear behavior and fracture mechanism of the surfacing alloy. The results show, hypereutectic Fe-4.5 wt% B surfacing alloys with different Mo additions are mainly composed of primary (Fe, Mo)2B boride, eutectic matrix, and FeMo2B2. With the increase of Mo content in Fe-4.5 wt% B surfacing alloy, the continuous growth of the eutectic structure is blocked, which can inhibit the formation and expansion of cracks in the surfacing layer. With the increase of Mo, the wear resistance of Fe-4.5 wt% B alloy increases from 16.70 g-1 to 22.72 g-1. In the impact fracture experiment, Fe-4.5 wt% B surfacing alloy has high brittleness, the primary Fe2B is a transgranular fracture, and the interface between primary Fe2B boride and eutectic structure is an intergranular fracture. With the addition of Mo, the fracture mechanism of the surfacing alloy changes from transgranular fracture to transgranular fracture + ductile fracture, which reduces the fragmentation and spalling during the wear process, thereby improving its wear resistance.

Fracture toughness and fractographic investigation of polybutylene terephthalate/thermoplastic polyurethane binary blends reinforced by multi-walled carbon nanotubes using essential work of fracture approach

In this paper, fracture toughness evaluation of polybutylene terephthalate (PBT)/thermoplastic polyurethane (TPU) binary blends and PBT/TPU/carbon nanotubes (CNTs) ternary nanocomposites have been conducted using both Izod impact and quasi-static fracture tests. Essential work of fracture (EWF) approach is used to study the fracture properties in details. The results of EWF tests revealed an effective role of TPU and CNTs in toughening mechanism of binary blends and ternary nanocomposites. According to EWF results, both the crack resistance and plastic deformation energies promoted in all compounds as compared to neat PBT. Energy dissipation in the yielding and tearing stages determined by the energy partitioning method. The obtained results indicated that displacement up to the failure point increased by increasing the TPU content, while inclusion of CNTs reduced this quantity. The specific non-essential work of fracture [Formula: see text] , [Formula: see text], and [Formula: see text] increased with increasing the TPU contents which is confirmed by load-displacement curves. Whereas, addition of CNTs reduced [Formula: see text] and [Formula: see text] values as compared to reference binary blend, however, ternary nanocomposites still have higher values as compared to pure PBT. In contrast with EWF results, high strain rate of impact test prevents the activation of toughness improving mechanisms that readily occurs in quasi-static loading.

Study on the fracture toughness and deformation micro-mechanisms of PP/EPDM/SiO2ternary blend-nanocomposites

A detailed fracture analysis of polypropylene/ethylene–propylene–diene monomer rubber/nano-silica (PP/EPDM/SiO2) ternary blend-nanocomposites was conducted through using both Izod impact and quasi-static fracture tests. The phase morphology and the fractured surfaces were evaluated using scanning electron microscopy. Morphological observations revealed that the SiO2nanoparticles were mainly located either around the EPDM particles or at the PP/EPDM interface. A synergistic effect was observed between the soft EPDM rubber particles and rigid SiO2filler on activation of different toughening micro-mechanisms, so that the impact strength of the ternary systems was significantly higher than that of corresponding binary blends. This effect was much more significant for percolated morphologies. The concept of the essential work of fracture (EWF) was used to analyze the fracture behavior and toughening/deformation mechanisms of the samples. The percolated structure of the EPDM particles and the SiO2nanoparticles exhibited superior fracture resistance under EWF fracture tests. Formation of multiple void-fibrillar structures dissipated further energy and significantly improved fracture resistance under EWF tests. It was demonstrated that the toughness and stiffness could successfully be balanced via controlling the microstructure of the ternary systems.

(Keynote) All-Atomistic Molecular Dynamics Calculation of Impact Fracture of Glassy Polymers

Impact-resistance has been one of the target properties of polymer technology from a view point of their mechanical applications. A huge number of investigations have been done for this very important property. One of the key to understand the impact resistance is to investigate the difference in microscopic behavior between brittle and ductile fractures by comparing two extrema of industrial polymers such as PMMA and PC, respectively. However, in spite of an abundance of information about macroscopic behavior of the impact fracture, little has been known about its microscopic picture. This is from difficulty in experiment for the very rapid phenomena.Molecular dynamics (MD) calculation has been one of the powerful tools for investigating microscopic behavior of molecular assemblies at an atomistic resolution. However, so far, poor performance of the supercomputers has prevented us from investigating polymers based on all-atomistic MD calculations since the systems are huge. Then, we have been obliged to depend upon coarse-grained models such as Kremer-Grest model and DPD model. But, they are not good at describing chemical character of polymers which is essential for the investigation of fracture. However, recent very rapid progress of supercomputer technology is going to enable us to investigate polymers based on all-atomistic MD calculations free from phenomenological parameters. The all-atomistic model can describe chemical details of the polymers, which is essential for the investigation of the diversity of polymers. Fracture of the polymers depends much on their chemical details such as main-chain bond breaking and side-chain motions.In particular, it is very important to include bond fracture in the simulation. Since most of the traditional MD calculations have not included bond breaking explicitly, the calculations couldn’t describe brittle fracture of polymers but always resulted in artificial ductile fracture. The bond fracture can be described using potential function such as Morse-type one. The function can be obtained by high quality quantum chemical calculations prior to the MD calculations. In the present study, brittle fracture has been investigated for PMMA including bond fracture explicitly. Systems constructed for the simulation mimicked the real system. There, experimental molecular weight distribution, density, radius of gyration, and entanglement molecular weight were reproduced well in the initial configuration prepared for the impact fracture test calculations. The calculations clearly show characteristics of the brittle fracture at a molecular level such as void formation, chain reactions of main-chain bond breaking, and small Poisson ratio.

Impact fracture behaviors of three-dimensional braided composite U-notch beam subjected to three-point bending

Impact fracture behaviors of three-dimensional braided composites are critical to designing the braided composite parts. Here we report the impact fracture behaviors of three-dimensional braided composite U-notch beam tested on a modified split Hopkinson pressure bar. Crack mouth opening displacement, deformation process, and crack evolutions were recorded with high-speed photography camera. The digital image correlation method was used to calculate deformation contours of the braided composite. A microstructure model of the three-dimensional braided composite U-notch beam was established for analyzing damage evolution and fracture mechanisms. The histories of deformation, the load, and the crack mouth opening displacement were obtained from the impact fracture test and finite element analysis. It was found that the impact fracture resistance and morphologies were influenced by the braided structure and braided yarn orientations. The crack generated at the notch tip and then propagated along the braided angle direction rather than the perpendicular direction that often occurred for isotropic materials, such as the epoxy resin solid. The combinations of different braided angle and yarns are recommended for high impact fracture behavior design.

Fracture resistance and micromechanical deformations in PP/PA6/EPDM ternary blends: Effect of rubber functionality, dispersion state and loading conditions

Polypropylene (PP)-based ternary blends comprising 15 wt% polyamide 6 (PA6) and 15 wt% of either reactive or nonreactive ethylene-propylene-diene monomer (EPDM-g-MA or EPDM) rubber were prepared. A core–shell morphology was observed for reactive blends while nonreactive blends showed separately-dispersed morphology. The role of phase morphology, interfacial strength and dispersion state of the modifier particles in reactive blends (via applying different processing methods) on the fracture resistance of the resulting blends under both Izod impact and quasi-static fracture tests were clarified. The impact strength of reactive blends was significantly higher than that of nonreactive ones and strongly dependent upon the mixing procedure. The crack resistance of the blends was further studied by the essential work of fracture (EWF) method. The specific EWF (we) and non-EWF (βwP) values of nonreactive blend were interestingly higher than those of the reactive blends. The contributions of yielding (we,y and βywp,y) and subsequent tearing (we,t and βtwp,t) components on the fracture works were determined. The percolated structure of the core-shell particles exhibited superior fracture resistance under fracture tests. Multiple void-fibrillar structures were developed in the reactive blends. A synergistic effect of cavitation inside rubber particles and debonding-cavitation around the PA6 domains was observed in the nonreactive blend.

Real-time estimation of delamination occurrence induced by low-velocity impact in composite plates using optical fiber sensing system

Low-velocity impact is the one of the most critical events to reduce the reliability of composite structures, because it can generate hidden damages such as delamination inside the structures. In order to address this problem, impact monitoring systems have been suggested using various types of built-in sensors. Generally, such impact monitoring systems are consisted of impact localization and damage assessment. In this paper, a methodology of impact-induced delamination assessment was studied using fiber Bragg grating (FBG) sensors. Because of its multiplexing capability, FBG sensors are advantageous of monitoring large areas of target structures. However, it is hard to be applied in impact monitoring systems due to its low sensitivity and narrow bandwidth. In this study, a quantification method of delamination was examined with maintaining the merits of FBG sensors. For the acquisition of impact-generated acoustic emission (AE) signals, the commercial FBG system was adopted with a sampling frequency of 100 kHz. Then, the acquired AE signals during the low-velocity impact fracture tests were analyzed with the wavelet transform (WT) method for measuring the delamination areas due to different energies. Finally, it can be concluded that the quantities of WT detailed portions are linearly correlated with the delamination areas.

Impact of Reversed Austenite on the Impact Toughness of the High-Strength Steel of Low Carbon Medium Manganese

We elucidate the relationship between the volume fraction of austenite and the Charpy impact toughness in a medium-Mn steel in terms of microstructural evolution with impact temperature. Different from retained austenite in the matrix after direct quenching, sub-micron lath-shaped morphology-reversed austenite in medium-Mn steel was produced by intercritical annealing. We found that reversed austenite steadily affected the fracture mode; only ductile fractures and dimples decreased with decreasing impact temperature. After the impact fracture test, the content of reversed austenite in the matrix increased slightly with a decreasing impact temperature due to the stability of the austenite grains caused by recrystallization of α′ martensite. Reversed austenite slightly decreased during the impact process with a decreasing impact temperature.

Effect of localization of carbon nanotubes on fracture behavior of un-vulcanized and dynamically vulcanized PP/EPDM/MWCNT blend-nanocomposites

Effect of localization of multiwall carbon nanotube (MWCNT) on the fracture toughness and deformation mechanisms of un-vulcanized and dynamically vulcanized polypropylene/ethylene-propylene terpolymer/multiwall carbon nanotube (PP/EPDM/MWCNT) blend-nanocomposites were investigated under both the Izod impact loading and the essential work of fracture (EWF) test as quasi-static loading conditions. The localization of MWCNT in the PP matrix led to increased impact fracture toughness via multiple crazing and crack deviation induced by MWCNT aggregates in the PP matrix, while it had negative effect on the fracture toughness under EWF test condition through hindrance effect on the yielding and necking processes. This contradiction was attributed to the different dominant deformation mechanisms in the PP matrix under high speed multiaxial Izod impact and low speed plane biaxial EWF fracture tests (crazing and shear yielding, respectively). Although the various toughening mechanisms such as nano-bridge mechanism were activated during the fracture processes, vulcanization induced interfacial adhesion improvement between the PP and EPDM particles played the main role in determining of the fracture toughness of the vulcanized blend-nanocomposites.

Compatibilization and toughening of co-continuous ternary blends via partially wet droplets at the interface

This work reports that a partially wet phase can compatibilize and toughen a co-continuous PLA/PA11 blend. Four different polymers: PBS, PBAT, EMA and EMA-GMA are examined for their capacity to partially wet the PLA/PA11 interface in a melt-blending process. All the blends exhibit a partial wetting morphology, but offer very different compatibilization efficacies and toughening effects. EMA-GMA demonstrates the best compatibilization effect as it reduces the co-continuous thickness to 5–6 μm, which is about half that of the original binary PLA/PA11 blend, followed by EMA while PBS and PBAT result in the least changes in morphology and properties. Despite the enhanced compatibilization effect obtained with EMA-GMA, it is the self-assembled droplets of EMA at the PLA/PA11 interface which result in a major increase in the ductility of the blend with an elongation at break of 260% as compared to 4% for the binary blend. A substantial increase in the notched Izod impact strength is also achieved with partially wet droplets of EMA with a value of 73 J/m, a four-fold increase as compared to the impact strength of the pure PLA and the PLA/PA11 binary blend. This difference is attributed to the limited internal cavitation of the very fine droplets of EMA-GMA at the interface whereas the blends with partially wet EMA demonstrate significant interfacial cavitation after the impact fracture test. This work shows that self-assembled rubbery EMA droplets at a co-continuous PLA/PA11 interface combine to compatibilize the system, improve interfacial adhesion and interfacially cavitate through the continuous system upon fracture. The percolation of the stress field around these interfacially cavitated partially wet droplets results in the shear yielding of the matrix and a significant toughening effect ensues. These results indicate the potential of partially wet droplets to compatibilize and toughen co-continuous structures.

Determination of Fracture Toughness by Single and Double Action Tensile Impact Fracture Tests

The characterization of the loading rate dependence of the fracture behavior of polymers is of prime theoretical and practical interest for supporting demanding engineering applications. To gain more insight into the high rate fracture behavior of polymers, fracture tests were performed under tensile loading conditions up to 12 m/s loading rate using a neat model polymer (PVC grey) in this study. A conventional single actuator test set-up for compact tension C(T) specimens was developed based on the previous experience of the authors and implemented on a new high rate servohydraulic testing machine. In addition, a novel double action test set-up was developed by applying two twin actuators and implemented in a rigid horizontal test frame. The conventional load and force measurement was extended by instrumented test specimens and by a high speed optical strain analysis system for both set-ups. Force based fracture toughness values using the peak load values, KIcPL and displacement based values using the critical crack opening displacement (CTOD) KICCTOD were determined up to a loading rate of 10 m/s. While the KIcPL values decreased up to a loading rate 103 MPam1/2s-1 an increase with a high data scatter was observed above them. Corresponding to the CTOD values the calculated KICCTOD values revealed a slight decrease and moderate data scatter up to the maximal loading rate.

Studies on mechanical properties, microstructure and fracture morphology details of laser beam welded thick SS304L plates for fusion reactor applications

Austenitic stainless steel is widely used structural material for the fabrication of the fusion reactor components. Laser welding is high power density process which offers several advantages over the other conventional processes like Tungsten Inert Gas welding. The features like low distortion, narrow heat affected zone, deep penetration in single pass, good mechanical properties are some of the advantages of laser welding process. The laser weld process parameters optimization has several challenges in terms of overcoming the weld defects like voids due to lack of penetration over depth, undercuts and porosity. The present paper reports the studies carried out with CO2 laser welding of 8mm thick austenitic stainless steel SS304L plates and their characterization of mechanical properties, microstructure and fracture morphology details. The weld process parameter optimization towards defect free welds with full penetration welding has been carried out. The welded samples have shown tensile properties comparable to base metal, bend tests are successfully passed. The hardness measurements have shown slightly higher for weld zone compared to base metal and the impact fracture tests have shown lower values for the weld zone (WZ) and heat affected zone (HAZ) compared to base metal (BM). Microstructure studies revealed the combined dendrite and columnar type features attributed to the higher cooling rates involved with laser welding process. Delta ferrite is observed in small residual contents in the weld zone and confirmed with Ferrite Number (FN) data. Scanning electron microscopy (SEM) studies have been carried out for the surface fracture morphology analysis for the tensile and impact tested samples to understand the ductile and brittle fracture details.

Impact Fracture Study of Laminated Composite Using Single Edge Notched Bend Specimens

The results of an investigation of impact fracture in laminated composite material are presented in this paper. Low velocity impact fracture tests were carried out on single edge notched three-point bending (SENB) specimens using a drop-weight rig. An inclined notch was introduced in the SENB specimen in order to generate mixed-mode I/II crack loading conditions. Different mixed-mode ratios were obtained by varying the notch inclination from 10° to 90° with a step of 10°. The SENB specimens were subjected to various impact potential energies by varying the drop-height in order to determine the critical impact potential energy at which the crack growth initiates from the initial notch tip position for each of the considered notch inclinations. The mechanical response of the SENB specimen to impact loading was analyzed using a two-dimensional linear-elastic finite element model. Good agreement was obtained between the predicted contact force – time curve and the measured one at various impact potential energy levels and notch inclinations. The strain energy release rate mode components were computed by the virtual crack closure technique. The composite fracture toughness under impact loading was characterized in terms of the critical dynamic strain energy release rate at the onset of crack growth. It was found that the fracture toughness under impact loading increases with decreasing the notch inclination. This finding was attributed to the increase of mode II component of crack loading. A comparison of the fracture behaviour under impact and static loading was performed. It was found that the fracture toughness under impact loading was between 19% and 23% lower than the static one for the different notch inclinations. Therefore, it was concluded that static fracture toughness should not be used in the fracture mechanics based design of composite structures which are subjected to impact loading during their lifetime.

Mechanical properties and microstructural investigations of TIG welded 40 mm and 60 mm thick SS 316L samples for fusion reactor vacuum vessel applications

The development of advanced fusion reactors like DEMO will have various challenges in materials and fabrication. The vacuum vessel is important part of the fusion reactor. The double walled design for vacuum vessel with thicker stainless steel material (40–60mm) has been proposed in the advanced fusion reactors like ITER. Different welding techniques will have to be used for such vacuum vessel development. The required mechanical, structural and other properties of stainless steels have to be maintained in these joining processes of components of various shapes and sizes in the form of plates, ribs, shells, etc. The present paper reports characterization of welding joints of SS316L plates with higher thicknesses like 40mm and 60mm, prepared using multi-pass Tungsten Inert Gas (TIG) welding process. The weld quality has been evaluated with non-destructive tests by X-ray radiography and ultrasonic methods. The mechanical properties like tensile, bend tests, Vickers hardness and impact fracture tests have been carried out for the weld samples. Tensile property test results indicate sound weld joints with efficiencies over 100%. Hardening was observed in the weld zone in non-uniform manner. Macro and microstructure studies have been carried out for Base Metal (BM), Heat Affected Zone (HAZ) and Weld Zone (WZ). Scanning Electron Microscopy (SEM) analysis carried out for the impact fractured specimens show ductile fracture. The microstructural study and ferrite number data indicate the presence of high content of delta ferrite in the weld zone as compared to the delta ferrite in base metal.

48.3: Novel Fracture Resistant Glass for Mobile Display Cover

AbstractNovel fracture resistant glass named DragontrailTM X for mobile display cover was developed through fracture analysis of smartphones and tablet PCs. Cover glass design guideline to prevent cover glass fracture, higher compressive stress and lower central tension, was confirmed by extensive impact fracture tests. The glass was designed to achieve high compressive stress over 1000MPa at 30μm in depth of layer. The glass can be manufactured by float mass production process.

Synthesis and characterization of amorphous Al–Mg–B prepared by various deposition temperatures

Amorphous Al–Mg–B thin films were synthesized via a combinatorial sputtering approach. The properties of Al–Mg–B films with the varying deposition temperature was investigated. The deposition temperature was found to dominate the hardness of the amorphous as-deposited film. The hardness increases with increasing deposition temperature and may even exceed that of crystalline AlMgB14 material. The high hardness may be attributed to the existence of randomly distributed B12 icosahedra structure. Therefore, the thin film that was deposited on cemented carbide shows well-cutting performances in turning Ti alloy bar. At the same time, an appropriate method of pretreatment is the key to ensure the coating tool with the excellent adhesion by impact fracture test.