Changes In Tensile Properties Research Articles

Mechanical Properties of Large Diameter Pipe with Increased Deformation Capacity (For Active Tectonic Fracture Zones)

Results are summarized for testing the mechanical properties of pipe of strength class K60 (corresponds approximately to strength category X70) with increased deformation capacity 1420 mm in diameter with wall thickness of 25.8 and 32.0 mm of industrial batches. The change of tensile test properties of basic pipe metal of the pipes after simulating application of an anticorrosive coating (200–250 °C, 5 min) and strain ageing is shown. After heating the pipe base metal retains low values of σy(Rt0.5)/σf ratio (along the rolling direction 0.75–0.84) and good ductility (along the rolling direction δ5 ≈ 22–23% and δt ≈ 8–12 %; across the rolling direction δ5 ≈ 21–22 % and δt ≈ 8–12 %). Relationships are determined for properties whose values depend on the specific nature of the steel microstructure of these pipes σy(Rt0.5)/σf, δt, KCV–40, CTOD–20). An increase in strength (σf) of the basic metal up to the upper standard limit does not lead to a reduction in ductility. However, with high strength pipe base metal there is a tendency towards a reduction in CTOD–20 values of base metal and fusion zone metal.

Dicing Tape Performance in a Plasma Dicing Environment

Plasma dicing, as a means of isolating individual integrated circuits from within a fully processed semiconductor substrate, is still an emerging technology but is now considered the latest step in the evolution in device singulation. With the trend towards smaller, thinner more robust devices, many chip manufacturers are considering, or already switching, to a plasma dicing approach.[1, 2] The high aspect ratio, deep reactive ion etching of silicon using a Bosch process, leverages some distinct advantages over the more physical methods of device singulation. [3] Although the more established methods of diamond blade saw dicing, various laser based approaches or laser/mechanical hybrid dicing techniques, all introduce an element of heat and in some cases water for cooling purposes, they do not expose dicing tape to the unique conditions within high vacuum plasma. This work investigates how the properties of both dicing tape and adhesive are affected when exposed to the environment of a plasma dicing process used in the semiconductor industry. A preliminary fitness test utilising an aggressive exothermic etching regime was used to establish the compatibility of a range of standard Lintec Adwill dicing tapes. In essence, a measure of base film thermal conductivity and how quickly some of the lower molecular weight volatile components of base film and adhesive materials are boiled off or ‘out-gassed’. Polyvinyl Chloride (PVC) tapes performed less well than Polyethylene terephthalate (PET) tapes and some of the Polyolefin (PO) tapes exhibited the greatest resilience. A design of experiments to measure changes in tensile strength, elongation and adhesive properties were carried out to assess the performance of plasma dicing on PO low adhesion tape. Figure 2 shows that the samples exposed to an SF6 plasma impacted the tape elongation and tensile strength properties. Typically the stretch required for PnP is in the range 1–10 % showing that the plasma dicing does not impact the overall performance of the tape. Further tests employing a die pick-up force measurement system to compare saw diced die with that of plasma diced die, proved the feasibility of this technology. Figure 3 shows that pick-up force measured on plasma diced dies is comparable with saw diced dies.

INFLUENCE OF THE STATE OF THE SURFACE ON THE DEFORMATION BEHAVIOR OF PRODUCTS AND IMPROVEMENT OF AUTO SHEET PRODUCTS FORMABILITY

It is known that most of the destruction processes (wear, fatigue crack initiation, corrosion) start in the surface layer. This allows us to consider the surface of the loaded product as an independent subsystem, whose behavior in the deformation process differs from the inner layers and has a significant impact on the properties of the product as a whole. Basically, surface treatment serves as a way to improve special performance characteristics (wear resistance, fatigue strength, heat resistance, corrosion resistance, etc.). However, information on the effect of modifying thin surface layers on the behavior of the deformation and mechanical properties of products made of common structural steels is of undoubted interest. This work is devoted to studying the possibilities of solving the actual problem of increasing the strength of products while maintaining plasticity (structural strength), as well as improving the technological characteristics of their material by changing the surface state. To address this issue, the effect of cementation, nitrating and ion bombardment of the surface of steel samples (steel 20, 40X, 08кп) on their deformation behavior and change in tensile properties was investigated. In addition, the issue of the influence of the state of the surface layer on the technological plasticity of cold-rolled auto sheet steel 08кп, intended for the manufacture of products by the method of cold forging, was also studied. It has been established that cementation always embrittles the product while maintaining a viscous and plastic core. In nitrated specimens, the nature and magnitude of the effect of a change in tensile properties depend on the layer thickness. With a shallow depth of the layer (0.08 mm), the strength increases while maintaining high ductility. A layer thickness of 0.25 mm or more leads to a decrease in strength, loss of ductility and brittle fracture. Ion bombardment is a very effective way to increase the structural strength and reliability of products - with increasing strength, an increase in plasticity of 2 or more times is provided. A significant improvement in the formability of 08кп cold-rolled steel was also found (the ГВ category, provided for it by GOST 9045-93, is increased to the requirements of the higher category of ВОСВ, recommended for more ductile and cleaner steel by 08U). The advantage is that an improvement in the ability to stretch is achieved not due to the softening of the sheet, but on the contrary, with increasing strength and resistance to destruction. Such effects cannot be obtained by any method of volume processing. It is important to conclude that changes in the deformation behavior and mechanical properties are not obtained by changing the material properties of products, but under the influence of the state of the surface layer.

Effect of bamboo fiber on the degradation behavior and in vitro cytocompatibility of the nano-hydroxyapatite/poly(lactide-co-glycolide) (n-HA/PLGA) composite

To obtain an ideal nano-hydroxyapatite/poly(lactide-co-glycolide) (n-HA/PLGA) composite for bone materials, bamboo fiber (BF) was selected to reinforce n-HA/PLGA. The effects of different loadings and surface modification methods for BF on in vitro degradation behavior and cell viability of n-HA/PLGA were evaluated. In vitro degradation was tested in a simulated body fluid while cell viability experiment was carried out using human osteoblast-like cells (MG-63). The changes of tensile strength, water absorption, surface microstructure and thermal properties during the soaking were investigated by means of electromechanical universal tester, scanning electron microscope and differential scanning calorimeter. Moreover, the cell attachment and proliferation of samples were evaluated by fluorescence microscope, inverted microscope and MTT method. The results showed that the degradation started from the interface between BF and n-HA/PLGA matrix, and the degradation rate of the BF/n-HA/PLGA composite was accelerated with the increasing BF amount. Fortunately, the surface-modified BF could improve the interface compatibility and display more suitable degradation rate. In addition, the in vitro cell incubating experimental results reflected that BF was nontoxic and had no side effect on cell attachment and proliferation. Especially, BF/n-HA/PLGA composite with 5% surface-modified BF had better cytocompatibility. The study suggested that the surface-modified BF had a great potential in developing BF/n-HA/PLGA composite used as bone materials in the future. Bamboo fiber (BF) played an important role in improving the mechanical property of n-HA/PLGA composite. Here, the effect of different contents and surface modification methods for BF on in vitro degradation behavior and cell viability of n-HA/PLGA composite was comprehensively study by the experiments of soaking in simulated body fluid (SBF) and incubating with human osteoblast-like cells (MG-63). The results showed that the incorporation of BF accelerated the degradation of the BF/n-HA/PLGA composite, and the composite with higher BF content had faster degradation. Fortunately, the surface-modified BF made the composite has more suitable degradation than the unmodified BF. Moreover, in vitro cell incubating experiment results reflected that BF was nontoxic and exhibited no side effects on cell attachment and proliferation of the BF/n-HA/PLGA composite. Especially, BF/n-HA/PLGA composite with 5% surface-modified BF displayed better cytocompatibility. In brief, the study suggested that BF had a great potential in developing BF/n-HA/PLGA composite used as bone materials in the future.

Effect of surface modification of titanium dioxide on the UV‐C aging behavior of silicone rubber

ABSTRACTSurface modification of titanium dioxide (TiO2) nanoparticles (NPs) by silane coupling agents and the ultraviolet‐C (UV‐C) aging behavior of silicone rubber (SiR) incorporated with the modified TiO2 NPs were investigated in this work. The SiR samples incorporated with TiO2 NPs displayed excellent stability against the UV‐C radiation. In order to improve the dispersion of TiO2 NPs in the SiR matrix, the surface of TiO2 NPs was modified with 3‐aminopropyl triethoxysilane and 3‐trimethoxysilyl propyl methacrylate, respectively. The surface modification of TiO2 NPs was characterized by thermal gravimetric analysis and Fourier transform infrared spectroscopy. The dispersion stability of the pristine TiO2 NPs and surface silane‐modified TiO2 NPs was evaluated in an organic solvent (toluene). Effect of surface modified TiO2 NPs on the UV‐C aging behavior of SiR was evaluated in terms of the change of surface morphology, tensile properties, hardness, crosslinking density, and surface microstructure before and after the UV‐C aging. The results showed that surface modification of TiO2 NPs with silane coupling agents could improve the dispersion of TiO2 NPs in the SiR matrix. Moreover, the SiR with modified TiO2 NPs showed an improved aging resistance to the UV‐C radiation, compared with the samples with pristine TiO2 NPs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47170.

Effects of Lignin-Derived Polycarboxylic Acids on the Properties of Waterborne Polyurethane Elastomers

Lignin was modified by oxidation to prepare lignin-derived polycarboxylic acids (LPCAs), which can be introduced into waterborne polyurethane (WPU) elastomers through the interactions with the soft segments of WPU. The changes of water resistance, thermal and tensile properties of WPU elastomers were observed. After LPCAs were added, the water solubility of WPU elastomers was increased. Besides, the weight loss peak of the soft segments of WPU moved to the lower temperature, indicating that the decomposition of soft segments became easier and the interspace of the soft segments regions was enlarged by LPCAs. Comparing with the blank WPU elastomer, when the LPCA loading was 2.5 wt% (based on PPG-1000), the tensile stress of the LPCA-WPU materials at 100% and 300% strain increased 135.4% and 90.5% separately, and the modulus of elasticity in tension increased 383.6%. Therefore, LPCAs could serve as reinforcing fillers in WPU elastomers, which contributes to develop more functional and eco-friendly WPU materials. Moreover, the usage of lignin is broadened.

Effect of Rotation Speed on the Microstructure and Mechanical Properties of Friction-Stir-Welded CuSn6 Tin Bronze

Four-mm-thick CuSn6 tin bronze plates were friction stir welded at a constant tool traverse speed of 100 mm min−1. Favorable joints could be obtained with rotation speeds ranging from 600 to 1000 rev min−1, and groove was found on the surface of the joint under 400 rev min−1. The microstructure of the weld nugget zone was characterized by equiaxed recrystallized grains with heterogeneity along the thickness direction. Moreover, the grain size of the thermo-mechanically affected zone and stir zone increased with the increase in rotation speed. Hardness of the stir zone was higher than that of other zones due to microstructural refinement. There was little change in tensile properties of the defect-free welded joints. During tensile test, all of the defect-free joints were fractured at heat-affected zone with typical plastic fracture.

Effect of Process Parameters on Changes in Tensile Properties of Cotton Sewing Thread

Effect of Process Parameters on Changes in Tensile Properties of Cotton Sewing Thread

Cellulose Solvent Treatment for Paper Surface Modification

Handsheets from dissolving and abaca pulp, and abaca paper yarn were treated with alkaline cellulose solvent to improve their dry and wet strength properties. Handsheets from low DP (degree of polymerization) dissolving pulp had increased wet and dry strength properties by the solvent treatment while those from abaca pulp (high DP) were lowered. Abaca paper yarn has no significant change in tensile properties by the solvent treatment. These strength property variations were thought to be come from the degree of cellulose fiber dissolution caused by the solvent treatment.

Characterization of Alloy 600 joints exposed to a high-temperature supercritical-carbon dioxide environment

Two types of Alloy 600 joints, such as diffusion-bonded joint and Alloy 182 fusion-weld, were exposed to supercritical-CO2 environment at 550 and 650 °C (20 MPa) for 1000 h. The diffusion-bond region showed similar oxidation characteristics as parent Alloy 600, but the migration of diffusion bond line below oxide layer was observed due to the Cr-depletion induced recrystallization. For Alloy 182 fusion-weld, outer Mn-rich oxides (Mn3O4 and MnCr2O4) and a small amount of inner SiO2 mixed with chromia were formed due to high Mn and Si contents. The presence of SiO2 in chromia suppressed carburization at the oxide/matrix interface, which resulted in the formation of an amorphous C layer between the outer Mn-rich oxide and inner Cr-rich oxide. For Alloy 182 fusion-weld, tensile property changes after exposure to supercritical-CO2 environment were negligible.

Mechanical Properties of Thixoforged In Situ Mg2Sip/AM60B Composite at Elevated Temperatures

The mechanical behaviors of the thixoforged in situ Mg2Sip/AM60B composite at elevated temperatures were evaluated. The results indicated that the thixoforged composite exhibits higher UTS (ultimate tensile strength) than that of the thixoforged AM60B at the cost of elongation. As the testing temperature rises from 25 to 300 °C, the UTS of both these two materials decreases while their elongations increases. The enhanced dislocation motion ability, the softened eutectic β phase at 120 °C, the activated non-basal slipping and the dynamic recovery and recrystallization mechanisms at 150 °C are responsible for the change in tensile properties with testing temperatures. The fracture mode transforms from the ductile into the brittle as the initial strain rate increases from 0.01 to 0.2 s−1 at 200 °C.

Corrosion characteristics of a tungsten alloy die-casting mould material in molten aluminium alloy

To understand the corrosion characteristics of W90 tungsten alloy and compare them with those of conventional hot-worked steel (SKD61), immersion tests were carried out in molten aluminium alloy (ADC12). Severe corrosion occurred in SKD61, whereas the corrosion resistance of W90 was about 40 times greater, with little occurring even after 300 h immersion. However, significant microstructural changes occurred in W90 resulting from penetration of aluminium and silicon through grain boundaries to create WAl5 and WSi2 phases, detectable even after a few hours’ immersion. Relatively soft (hardness 1.5 GPa) WAl5 formed between the W based grains, and hard (10 GPa) WSi2 outside the W based grains. Tensile strength decreased slowly with increasing immersion time, while a significant reduction in fracture strain occurred. These changes in tensile properties were caused by the microstructural changes, e.g. soft and brittle intermetallic compounds. Crack propagated along the WAl5 phases (intergranular fracture), whereas transgranular fracture was dominant for uncorroded or less corroded W90.

Effect of sub-zero treatment on fatigue strength of aluminum 2024

Challenge of change of alloy properties during service life of extra safety parts was always considered by industrialists and consequently researchers. Fuselage and wings of airplane repeatedly in ascent and descent is affected respectively by cooling to − 55°C and heating to room temperature. Hence, the effect of above temperature changes on tensile and fatigue strengths are unknown. In this study in laboratory, the situation of airplane body is tried to simulate and then the changes of microstructure and consequently the changes of tensile properties and hardness after holding for 10 and 4h were studied respectively in temperatures of − 60°C and − 196°C. Results showed that by using of sub-zero treatment, hardness is without change but tensile properties are increased to control specimen. In addition, after sub-zero treatment, the fatigue limit of the control specimen has reduced at least 20%.

Possibilities for Change of Thermoplastic Tensile Properties Using Admixture of Recyclable Material

Polymeric materials are thanks its processing and utility properties materials in demand of common and special use. They are also largely replacing conventional materials. As the popularity of polymeric materials grows, also the amount of its waste increases. For this reason, there is introduced the term recycling as a method of processing, re-use of the waste, into technologies of polymeric processing. So, this paper deals with the possibilities of introduction of recycled material. The main part of this paper is created by an experiment that explores the changes of tensile properties of test specimen according to the selected percentage of additives in the volume of the basic granulate. The test specimen was produced by mixing pure granules with the addition of recycled and re-granulated materials. The conclusion of this work presents a comparison of the results of each tensile test that provide an overview of the behaviour and properties of the materials tested.

Studies on Tensile Properties of Compatibilized and Uncompatibilized Low-Density Polyethylene/Jackfruit Seed Flour (LDPE/JFSF) Blends at Different JFSF Content

Currently, natural fillers seem to be the suitable materials in polymer industry, which have emerged as a viable and abundant replacement for the relatively high-cost and non-renewable conventional fillers. However, the direct introduction of natural fillers into polymer matrix could effect negatively on some properties. Therefore, the aim of this work is to evaluate the influence of jackfruit seed flour (JFSF) (before and after compatibilization) on the tensile properties of (LDPE/JFSF) blends. Different JFSF content (5, 10, 15 and 20 wt.%) with (63-100 𝜇𝑚) particle size were prepared in this work. Twin-screw extruder at 150°C and 50rpm screw speed followed by hot-compress machine at 150°C and 10MPa pressure were used respectively to produce (LDPE/JFSF) blends. Adipic acid (AA) solution was added as a compatibilizer into all blends equally (25wt% AA into 75wt% JFSf). The changes of tensile and morphological properties were investigated. Results shown decreasing on tensile strength and elongation at break of LDPE/JFSF and LDPE/JFSF/AA as JFSF increased. In contrast, Young’s modulus increased up to 10 wt.% of JFSF and then decreased. However, the addition of Adipic acid, particularly for JFSF 5wt.% has improved the tensile properties of LDPE/JFSF blends. The SEM micrographs showed the agglomeration at high JFSF content (20 wt%) which in turn effected negatively on the tensile properties. However, the blends show homogeneous surfaces as AA added.

Evaluating polymer degradation with complex mixtures using a simplified surface area method

ABSTRACTChemical-resistant gloves, designed to protect workers from chemical hazards, are made from a variety of polymer materials such as plastic, rubber, and synthetic rubber. One material does not provide protection against all chemicals, thus proper polymer selection is critical. Standardized testing, such as chemical degradation tests, are used to aid in the selection process. The current methods of degradation ratings based on changes in weight or tensile properties can be expensive and data often do not exist for complex chemical mixtures. There are hundreds of thousands of chemical products on the market that do not have chemical resistance data for polymer selection. The method described in this study provides an inexpensive alternative to gravimetric analysis. This method uses surface area change to evaluate degradation of a polymer material. Degradation tests for 5 polymer types against 50 complex mixtures were conducted using both gravimetric and surface area methods. The percent change data were compared between the two methods. The resulting regression line was y = 0.48x + 0.019, in units of percent, and the Pearson correlation coefficient was r = 0.9537 (p ≤ 0.05), which indicated a strong correlation between percent weight change and percent surface area change. On average, the percent change for surface area was about half that of the weight change. Using this information, an equivalent rating system was developed for determining the chemical degradation of polymer gloves using surface area.

Change in Tensile Properties of Dual-Phase Steels by Cu Addition

The effect of Cu addition on the tensile properties of dual-phase steels with various volume fractions of martensite was investigated. An increase in the intercritical-annealing temperature resulted in an increase in the volume fraction of martensite and in the hardness of steel. The Cu addition increased the hardness of steel for all volume fractions of martensite. The tensile properties strongly depended on the Cu addition and on the volume fraction of martensite. The Cu addition significantly increased the ultimate tensile stress and elongation, but it showed a negligible influence on the 0.2% proof stress. The Cu addition improved strength–ductility stability, which referred to the multiplication of ultimate tensile stress and uniform elongation, for all volume fractions of martensite. Modified Crussard–Jaoul analysis on the true stress–true strain curve indicated that the work-hardening behavior of steel was improved by adding Cu. In pre-strained steels, the dislocation density was increased by adding Cu for all volume fractions of martensite. The improvement in work-hardening behavior was explained by the increase in dislocation density attributed to the addition of Cu. Therefore, it could be concluded that the Cu addition could increase dislocation density and work hardening, thereby increasing the ultimate tensile stress and improving the strength–ductility stability of steel.

Tensile properties of F82H steel after aging at 400–650 °C for 1000–30,000 h

The present study conducted tensile tests on F82H steel after aging at 400–650°C for 1000–30,000h, and discusses the process for change in tensile properties during the long-term aging, combined with previous study for 100,000h aging. The limit for aging time to keep tensile strength is more than 100,000h for 400 and 500°C aging, 10,000h for 550°C, 3000h for 600°C, and less than 1000h for 650°C. While, no degradation of ductility was detected after all the aging examined. Regression analyses were performed with Hollomon-Jaffe parameter and Lambda parameter on the degradation of tensile strength during aging, and prior tempering in the heat treatment before the aging. Lambda parameter analysis successfully derived a master curve to describe the tensile strength after the long-term aging.

Ductile‐to‐brittle transition behavior of low molecular weight polycarbonate under carbon dioxide

We investigated the stress–strain behavior of low molecular weight polycarbonate for optical disc grade (OD‐PC) under carbon dioxide (CO2) at various pressures, and compared the results with that under ambient pressure at various temperatures. Elongation at break decreased sharply with increased CO2 pressure at around 2 MPa, while the elastic modulus decreased gradually up to 6 MPa. These results indicate that the tensile property changed from ductile to brittle with increased CO2 pressure, although the molecular motion is accelerated due to the plasticization effect of CO2. Such ductile‐to‐brittle transition is similar to that observed under elevated temperatures caused by chain disentanglement due to accelerated molecular motion. Although the changes of tensile properties were similar, the craze structure obtained by the brittle behavior was different, i.e., a filamented‐craze structure was obtained under high‐pressure CO2, while a lace‐like one was obtained under elevated temperatures. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers

The effect of extrusion conditions on the properties and textures of AZ31B alloy

Abstract The effect of extrusion conditions on the tensile properties and texture of AZ31B alloy has been investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and tensile tests. It is found that the ultimate tensile strength (UTS), the yield strength (YS) and elongation (EN) of the extruded AZ31B alloy are more significantly influenced by extrusion velocities in contrast with temperature. Although the extrusion conditions are different, the { 11 2 ¯ 0 } 〈 01 1 ¯ 0 〉 texture is the chief texture in the AZ31B after extrusion. Moreover, the extrusion textures become scattered with increasing the temperatures at the same extrusion velocity. As the extrusion velocity is raised at the same temperature, the orientation density of textures increases and the separated textures become relatively concentrated. This leads to the changes of tensile properties at different extrusion conditions.