Average Ultimate Tensile Strength Research Articles

Microstructural and mechanical characteristics of 308L stainless steel manufactured by gas metal arc welding-based additive manufacturing

In this paper, gas metal arc welding-based additive manufacturing (GMAW-AM) was used to build thin-walled 308L stainless steel parts. The microstructural and mechanical characteristics of the built thin walls were investigated. The results show that the GMAW-AM thin-walled 308L is dominantly composed of columnar dendrites, which grow along the build direction when increasing the number of depositing layers. The microstructure of the GMAW-AM thin-walled 308L mainly consists of two phases: a small amount of δ ferrite phases displayed within γ austenite dendrites. The microhardness of built materials ranges from 155 ± 1.20 HV0.1 to 169 ± 5.67 HV0.1. The average ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) of the GMAW-AM thin-walled 308L in the vertical direction are 531.78 ± 4.52 MPa, 343.67 ± 7.53 MPa, and 39.58 ± 1.38%, respectively, which are obviously lower than those in the horizontal direction (UTS: 552.95 ± 4.96 MPa, YS: 352.69 ± 8.12 MPa, and EL: 54.13 ± 1.29%).

Development of high strength suction cast hypereutectic Al–20Si alloy containing gamma alumina and strontium

ABSTRACTIn this research, the hypereutectic Al–20Si alloy, containing an optimised amount of 4 wt-% γ-Al2O3 and 0.1 wt-% strontium, was successfully synthesised through the suction casting process. The cooling rate (563 K s−1) involved during solidification was estimated by measuring secondary dendritic arm spacing. As a result, a significant change in the morphology of silicon was observed and also led to the formation of a small fraction of refined α-Al throughout the microstructure. The work demonstrates that high tensile properties in hypereutectic Al–20Si alloys can be achieved without the use of conventional inoculants (such as phosphorus). The suction cast Al–20Si alloy exhibits remarkably enhanced tensile properties of average ultimate tensile strength of 355 MPa and average ductility of 7.1%.

Behavior of Hollow Core Slabs Reinforced with GFRP Prestressing Bars

An experimental program was designed to study the behavior of full-scale hollow core slabs prestressed with Glass Fiber-Reinforced Polymer (GFRP) bars in the concrete laboratory at the college of engineering, Mataria, Helwan University, Cairo, Egypt. The hollow core slabs were load-tested under uniformly distributed load. The GFRP bars were manufactured from locally available materials with a 10 mm nominal diameter. To improve the bond properties between the bars and concrete, GFRP threads were axially wrapped around the bars manually. The mechanical properties of the bars were investigated in the laboratory. The bars average ultimate tensile strength (fu) and elastic modulus (E) were 1000 MPa and 46 GPa, respectively. Four full-scale concrete hollow core slab specimens with characteristic strength of 80 MPa were constructed and solely reinforced with a single prestressed GFRP bar. Each slab specimen represented one complete vent with a width of 140 mm, 150 mm thickness and 4000 mm total length. These specimens were simply supported during the experiments where the GFRP bar was placed at the centerline of the vent near the soffit. The Bars were prestressed to different stress levels, namely (10, 20, 30 and 40%) of their ultimate tensile strength (fu). All slab specimens were load-tested under uniformly distributed load. The deflection, strain and crack pattern were investigated during load-testing. From the obtained results, it was observed that the optimum prestressing level was 20% of the ultimate tensile strength of the bar for both the moment carrying capacity and the deformation.

Effects of trace Nb addition on microstructure and properties of Ti–6Al–4V thin-wall structure prepared via cold metal transfer additive manufacturing

To refine the coarse columnar prior-β grains across the layers in the cold metal transfer additive manufacturing (CMTAM) of a Ti–6Al–4V thin-wall structure, the addition of trace Nb, which functioned as heterogeneous nuclei, is proposed. After the addition of trace Nb powder, intra-layer bands were obtained in each layer of the Ti–6Al–4V wall, which divided each layer into two parts according to the existing forms of Nb, including a rich unmelted-Nb-powder zone and a (β-Ti, Nb)-phase-rich zone. The unmelted Nb powder with an average diameter of 170 nm—which acted as heterogeneous nuclei, promoting the columnar-to-equiaxed transition of prior-β grains—mainly existed in the lower zones of the layers. A random distribution of (β-Ti, Nb) phases was observed in the upper zones of the layers, which experienced the highest loads (398.8 mN) with indentation displacement of 2000 nm in nanoindentation tests. The trace Nb addition affected the interplanar distances of (β-Ti, Nb) phases and changed the solidification mode from planar to cellular. Tensile tests revealed that the average ultimate tensile strength increased from 990 to 1149 MPa, as the solution strengthening of the (β-Ti, Nb) phases played the dominant role in strengthening, while the average strain decreased from 7.69% to 5.5%. The unmelted Nb powder was the cause of the change in the fracture modes from ductile behavior to mixed behavior of cleavage and ductile fracture. During the CMTAM process, the possible thermal cycles for as-built and trace-Nb-addition specimens were analyzed.

Mechanical behavior of the metal parts welded with extraterrestrial regolith simulant by the solar concentrator in ISRU & ISRF application

The use of in-situ resources plays an important role on future extraterrestrial human activities for the facility repair and habitat construction, especially in sustainable space exploration of Moon and Mars. A method of the metal welded with extraterrestrial regolith simulant using solar processing under ambient conditions is presented. Metal parts are made of Q235B ferroalloy and TA2 titanium alloy into standard tensile members according to the ASTM code. They are disconnected from the middle in advance, and then welded together with lunar and Martian regolith simulant under ambient conditions, respectively. The entire welding process and precautions are detailed. Additionally, the mechanical behavior of weldments is characterized regarding their tensile strength. Furthermore, the fusion zone of weldments is studied by Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) measurements. The results show that it is possible to weld metal parts together with extraterrestrial regolith simulant by the solar concentrator. The average ultimate tensile strength of ferroalloy specimens welded with lunar and Martian regolith simulant is 2.94 MPa and 1.66 MPa; The average ultimate tensile strength of titanium alloy specimens welded with lunar and Martian regolith simulant is 4.95 MPa and 2.59 MPa. Moreover, the failure mode of all weldments was brittle failure. The welding joints strength derives from the phases that the regolith as the solder fusing into ferroalloys in a homogeneous way and titanium alloys in an inhomogeneous way. The presented method may provide a new thought for astronaut assistance associating with repairing and fabricating in subsequent Moon and Mars missions.

Mechanical and microstructural characterization of aluminium powder deposit made by friction stir based additive manufacturing

The full potential application of the powder-based additive friction stir (AFS) process can be hindered due to the consolidation of the powder inside the tool. In this work, a very simple method was proposed to negate this issue. The process was named as additive friction stir processing (AFSP) since its working principle was similar to the friction stir processing (FSP). A layer-by-layer 7 mm thick 3D structure from pure aluminium powder on an aluminium substrate was successfully fabricated by AFSP. The quality of the additive layers was assessed by examining its mechanical properties and microstructural characteristics. An increment of 36, 3, and 54 % in the average ultimate tensile strength, yield strength, and percentage elongation, respectively, were observed when comparing with AA1060-H12. Grain refinement of the filler aluminium powder was noticed. Fine grains with almost equal dimensions in short-transverse and transverse directions were also found, which revealed induced super-plasticity and isotropy in the deposit. The fractographic analysis was in good agreement with the ductile nature of the deposit.

Post-Process Effects of Isothermal Annealing and Initially Applied Static Uniaxial Loading on the Ultimate Tensile Strength of Fused Filament Fabrication Parts.

Fused filament fabrication (FFF) is one of the most popular additive manufacturing (AM) techniques used to fabricate polymeric structures. However, these polymeric structures suffer from an inherent deficiency of weak inter-laminar tensile strength. Because of this weak inter-laminar strength, these parts fail prematurely and exhibit only a fraction of the mechanical properties of those fabricated using conventional means. In this paper, we study the effect of thermal annealing in the presence of an initially applied static uniaxial load on the ultimate tensile strength of parts fabricated using FFF. Tensile specimens or dogbones were fabricated from an acrylonitrile butadiene styrene (ABS) filament with a glass transition temperature (Tg) of 105 °C; these specimens were then isothermally annealed, post manufacture, in a fixture across a given range of temperatures and static loads. Tensile testing was then performed on these specimens to gauge the effect of the thermal annealing and static loading on inter-laminar tensile strength by measuring the ultimate tensile strength of the specimens. A design of experiments (DOE) approach was followed to calculate the main and interaction effects of the two factors (temperature and static loading) on the ultimate tensile strength, and an analysis of variance was conducted. Cross-sectional images of the specimens were studied to observe the changes in the mesostructure of the specimens that led to the increase in inter-laminar strength of the parts. The results show that temperature plays a dominant role in increasing the ultimate tensile strength and an 89% increase in the average ultimate tensile strength was seen corresponding to an annealing temperature of 160 °C. A change in the mesostructure of the parts is seen, which is characterized by an increase in bond length and void coalescence. These results can be helpful in studying the structural strength of 3D printed parts, and thus could eventually guide the fabrication of components with strength comparable to those of conventional manufacturing techniques.

Stress corrosion behavior of narrow-gap rotating laser welding of thick Al-Mg alloy joint

The stress corrosion resistance of 30 mm-thick narrow-gap rotating laser welding (NG-RLW) 5A06 aluminum (Al) joint was investigated by slow strain rate testing (SSRT). The results show that the average ultimate tensile strength (UTS) of the joints in 3.5% NaCl solution is about 11% lower than that in air, and its elongation is only half of that in air. The stress corrosion index [Formula: see text] of the joint is [Formula: see text], which is at the middle level of the range of [Formula: see text]. Moreover, the failure positions of the SSRT specimens in air are weld metal (WM), while the failure positions in the corrosive medium are base metal (BM). This indicates that the stress corrosion resistance of BM is slightly lower than that of WM due to the different microstructures. Many dimples are formed on the fracture surface of the specimen in air, which is a typical ductile fracture. But the fracture surface shows the characteristics of ductile and brittle mixture with obvious corrosion products. This result indicates that the NG-RLW 5A06 Al joint has a tendency to brittle fracture in 3.5% NaCl solution.

Microstructure and Magnetron Sputtering Properties of Molybdenum Target Prepared by Low-Pressure Plasma Spraying

Planar molybdenum targets were fabricated by low-pressure plasma spraying (LPPS) under 2.6 × 104 Pa pressure. A lamellar structure consisting of vertical columnar grains and compact interlamellar contacts was found in the LPPS deposits. The oxygen content by mass, porosity, average grain size, microhardness, and ultimate tensile strength of the LPPS target were about 0.18%, 1.1%, 0.4 μm, 361.8 HV0.025, and 373.2 MPa, respectively. Electron backscattered diffraction (EBSD) analysis of the LPPS sample showed proportions of -, -, and -oriented grains of about 12.0%, 16.9%, and 9.2% of the total, respectively. The molybdenum target exhibited excellent magnetron sputtering performance, since most of the grains with size less than 1.0 μm were irregularly distributed without preferred orientation. Rapid sputtering and uniform thinning on the surface of LPPS molybdenum targets took place during magnetron sputtering. Smooth and continuous molybdenum thin film with thickness of about 700 nm could be deposited by magnetron sputtering from the LPPS samples. The x-ray diffraction (XRD) spectra of molybdenum thin film with body-centered cubic structure showed that the intensity of (110) diffraction peak was much higher than that of (220) one.

Effects of Cryogenic Deformation on Second-Phase Al2Cu Particles and Mechanical Properties of 2219 Al–Cu Alloy Rings

2219 Al–Cu alloy transition rings are widely used in launch vehicles. However, the coarse and agglomerated second-phase Al2Cu particles significantly deteriorate the mechanical properties and ductility of 2219 Al–Cu alloy rings manufactured by traditional thermal deformation processes. In this study, cryogenic deformation (− 190 °C) is applied for the manufacturing of 2219 Al–Cu alloy rings to alleviate this problem. The effects on the evolution of second-phase Al2Cu particles and the mechanical properties of the T8-aged samples were examined in comparison with the results of room-temperature (25 °C) and conventional thermal deformation at 480 °C. The results indicate that cryogenic deformation can effectively produce high-density dislocations and strongly crush coarse particles, promoting the dissolution of Al2Cu particles and improving their distribution in the Al matrix when combined with subsequent solution treatment and rolling processes. As the deformation temperature was decreased from 480 to −190 °C, the area fraction of the coarse particles was decreased from 1.55 to 0.47%, while their mean size was decreased from 11.8 to 8.3 μm. Correspondingly, the uniformity and density of the precipitates after T8 aging were improved. Thus, the mechanical properties of the T8-aged samples were improved with decreasing deformation temperatures; the average ultimate tensile strength, yield strength, and elongation were increased by 20 MPa, 22 MPa, and 3.1% at room temperature.

Strength-ductility trade-off via SiC nanoparticle dispersion in A356 aluminium matrix

A process was developed to disperse β-SiC nanoparticles (NPs), with a high propensity to agglomerate, within a matrix of A356 aluminum alloy. A suitable dispersion of 1 wt% SiC NPs in the A356 matrix was obtained through a hybrid process including a solid-state modification on the surface of the NPs, a two-step stirring process in the semi-solid and then the liquid-state, and a final hot-rolling process for fragmentation of the brittle eutectic silicon phase and porosity elimination. Titanium and nickel where used as the nanoparticle SiC surface modifiers. Both modifiers were found to improve the mechanical properties of the resulting material, however, the highest improvement was found from the nickel surface modification. For the nickel modification, compared to the non-reinforced rolled alloy, more than a 77%, 85%, and 70% increase in ultimate tensile strength (UTS), yield strength (YS), and strain % at the break, respectively were found with respect to the unreinforced rolled A356. For the rolled nanocomposite containing 1 wt % SiCnp and nickel modification, an average YS, UTS, and strain % at the break of 277 MPa, 380 MPa, and 16.4% were obtained, respectively, which are unique and considerable property improvements for A356 alloy.

Optimization of process parameters in fused filament fabrication (FFF) utilizing poly lactic acid (PLA)

This research was to find an optimum parameter in Fused Deposition Modelling, FDM. They are various type of printing parameter in 3D printing. The parameter that was focused on in this research are orientation, print head and layer thickness while other parameters will be fixed. This parameter was evaluated the mechanical properties of the printed parts. The mechanical properties will be performed on the specimen are tensile test and 3 point-bending tests. The data were analyzed using Taguchi’s Method with orthogonal array of 9 level and Analysis of Variance, ANOVA. The highest of ultimate tensile strength was 34 MPa where the parameter were 34.592 MPa. The highest of flexural strength was 95.542 MPa. The optimum parameter for the tensile test was 25-degree of orientation, 0.4 mm of print head and 0.2 for layer thickness. The optimum parameter for 3-point-bending test was 0-degree of orientation, 0.4 mm of print head and 0.15 mm of layer thickness. This parameter did the mechanical test again for the validation test. The average ultimate tensile strength value for 25-degree of orientation, 0.4 mm of print head and 0.2 for layer thickness was 30.558 MPa. While the average of flexural strength for 0-degree of orientation, 0.4 mm of print head and 0.15 mm of layer thickness was 95.557 MPa.

About the design, development of an automated SMAW setup and the weldment analysis in air and wet working environment

The aim of this research is to design and to develop a computer controlled low-cost underwater welding setup for shielded metal arc welding (SMAW) process to work in dry as well as in wet welding conditions. Investigations of the microstructure and mechanical properties of the welded joints made from AISI 1010 steel plates using this setup, in air, tap water, and saltwater working environment, respectively, have been carried out. Weld bead geometry, microstructure, ultimate tensile strength (UTS), ductility, impact strength and Vickers microhardness of air and wet welded joints have been characterized and compared. The general weld bead size is quite dissimilar for air, tap water and salt water welded joints. The tap water and salt water welds seem to be wider with a slightly higher weld penetration with lower reinforcement. The maximum value of the the average UTS of the welded sample as per ASTM was 485.74 MPa. The experiments showed that the maximum percentage of elongation of samples welded in different conditions is 8.06 % and the maximum value of the average impact strength of 25.64 J was found in case of air welds. The microhardness value of fusion zone (FZ) was greater than base metal (BM) in all the welded samples. It was noted maximum up to 310.8 HV10 at coarse grain heat affected zone (CGHAZ) of tap water welds. The mechanical properties of the salt water welds deteriorated due to porosity, slag inclusion, undercut, increase in hydrogen and oxygen content in the welds.

Selective laser melting of CoCrFeNiMn high entropy alloy powder modified with nano-TiN particles for additive manufacturing and strength enhancement: Process, particle behavior and effects

Selective Laser Melting (SLM) was applied for Additive Manufacturing (AM) of CoCrFeNiMn high entropy alloy (HEA) and TiNp/CoCrFeNiMn composite, with the tailored laser parameters for as-printed bulk densification after the process optimization. The pre-alloyed HEA powder by gas-atomization was modified with nano-TiN ceramic particles on the powder surface layer and employed to fabricate HEA matrix composite with uniformly dispersed TiN reinforcements via SLM. The hierarchical microstructures with strong crystallographic textures were generated in the as-printed HEA parts. While in the TiNp/HEA composite, the remarkably refined and nearly equiaxial HEA matrix grains were produced due to the contribution of introduced TiN particles. The average ultimate tensile strength (σUTS) of as-printed composite achieved 1036 MPa with the average elongation to fracture (ef) as ~12%. By contrast, the average σUTS and ef of as-printed HEA were 601 MPa and ~30% respectively. The strengthening mechanism of the SLM-fabricated TiNp/HEA composite was further elucidated.

Microstructure and magnetron sputtering properties of tungsten target fabricated by low pressure plasma spraying

Planar and rotary tungsten targets were fabricated by low pressure plasma spraying (LPPS). Relative density, oxygen content by mass, microstructure, micro-hardness and ultimate tensile strength (UTS) of LPPS tungsten targets were all influenced by vacuum pressure. Compared with 1.3 × 104 Pa and 6.5 × 104 Pa, a vacuum pressure of 3.9 × 104 Pa was optimal for preparing high-quality tungsten targets. Oxygen content by mass, porosity, average grain size, micro-hardness and UTS of LPPS target fabricated under 3.9 × 104 Pa were about 0.18%, 2.8%, 0.9 μm, 377.8HV0.025 and 201.1 MPa, respectively. Electron backscattered diffraction (EBSD) from the LPPS sample (fabricated under 3.9 × 104 Pa) showed that proportions of 〈001〉, 〈011〉 and 〈111〉 oriented grains were 10.6%, 21.0% and 12.3% of the total, respectively. The tungsten target possessed excellent magnetron sputtering performance since most tungsten grains with a size <1.0 μm were irregularly distributed without preferred orientation. Rapid sputtering and uniform thinning on the surface of LPPS tungsten targets took place with nano-scaled sputtering pits being formed during magnetron sputtering. Smooth and continuous tungsten thin films with thickness about 320 nm can be deposited by magnetron sputtering from the LPPS samples. XRD spectra of tungsten thin films with body centered cubic structure showed that the intensity of the (110) diffraction peak was much higher than those of the (200), (211) and (220) peaks.

Extraction and Characterization of Natural Fiber from Stem of Cardiospermum Halicababum

ABSTRACT The current study deals with the investigation on the properties of lignocellulose fiber from the stem of Cardiospermum Halicababum. The Cardiospermum Halicababum fibers (CHF) were extracted from its stem by manual retting process. The retted fibers were analyzed for various physical, chemical, crystalline, thermal stability, tensile and morphological properties as per standard procedure. From the chemical investigation, it was found that the CHF has cellulose (59.82%), hemicellulose (16.75%), lignin (9.3%) and wax (1.3%). The CHF possessed a crystallinity index of 32.21%, with thermal stability up to 336°C. The average ultimate tensile strength of CHF was 20.7 ± 1.0 MPa. Morphological characteristics showed lesser lacuna space in between the cell walls thereby preventing the reduction in strength properties.

Effect of ball milling on microstructure and mechanical properties of 6061Al matrix composites reinforced with high-entropy alloy particles

6061Al matrix composites reinforced by 7.5 vol.% nanocrystalline CoNiFeAl0.4Ti0.6Cr0.5 high-entropy alloy (HEA) particles have been synthesized by powder processing of powder mixture ball milled for 10 h, 20 h and 40 h. Results indicated that the average ultimate tensile strength and fracture strain of the 6061Al-HEA-10 h composite were 378 MPa and 8.4%, better than those of the 6061Al-HEA-20 h composite, which was related to the homogeneous distribution of HEA particles. Specifically, the 6061Al-HEA-40 h composite had the highest ultimate strength and yield strength, and the fracture strain was close to the 6061Al-HEA-20 h composite, related with the formation of fine HEA particle clusters and a heterogeneous grain structure. The strengthening mechanisms for the improved strength of the composites are mainly derived from the Hall–Petch effect and geometrically necessary dislocations.

Towards Qualification of Friction Stir Welding to AA5083-O and AA5052-O Aluminum Alloys

Friction Stir Welding (FSW) is an excellent alternative for joining dissimilar and similar materials in comparison to conventional welding processes. In this sense, this work aims at qualifying FSW to similar AA5083-O and AA5052-O aluminum alloys, with 6.35 mm thickness, in a CNC machining center. Therefore, four welding experiments were undertaken. At first, two types of plate surface finish were considered before joining. Afterward, two tool probe geometries, and changes in the base material position were evaluated. Hence, the welds were mainly analyzed by metallography, tensile testing, and bending tests. Results showed that the machining step to oxides removal and plates alignment is beneficial for the weld processing and the factor that has significant influence to achieve suitable joints is the tool probe geometry. Finally, by obtaining an average ultimate tensile strength (UTS) of around 191 MPa, enhanced microhardness, and bent angle of approximately 150°, the best joint was chosen.

Comparison of tensile properties between natural fibres and inorganic fibres for strengthening timber structures

Fibre-reinforced polymers (FRPs) have been successfully applied to the strengthening of reinforced concrete structures and a similar methodology is adopted by researchers in order to strengthen timber structures using synthetic fibres such as carbon, glass or aramid fibres. This paper explores the viability of using fibres from botanical sources for the reinforcement of timber structures. In this study, two natural fibre materials, namely kenaf and ramie, in combination with a polymeric matrix, are tested for their tensile properties in accordance with ASTM D 4018-99. The results indicate that kenaf fibres exhibit average ultimate tensile strength value at rupture of 750 MPa and Young’s modulus of 58 GPa. The test results also show that the corresponding parameters for ramie fibres average at 810 MPa and 36 GPa respectively. These values are closer to those of timber as opposed to analogous values for carbon and glass fibres. The strength and elastic moduli compatibility of both kenaf and ramie fibres with timber and contrast with carbon and glass fibres is further discussed in relation to the viability of using these natural fibres as reinforcement for timber.

Microstructure and Tensile Properties of the Fe-32%Ni-4%Co Alloy During Cryorolling and Subsequent Annealing

The Fe-32%Ni-4%Co alloy was cryorolled to produce thickness reductions of 10, 40, 60 and 90%; then, the strips with a final thickness of 0.52 mm were annealed at 893, 923 and 943 K for different soaking times. The x-ray diffraction measurements indicated that both thermally induced α′-martensite (α′-M) and deformation-induced α′-M were present in the tested alloy. The thermally induced α′-M was mainly lath-shaped, while the morphology of the deformation-induced α′-M gradually changed from lath-shaped to irregular-shaped according to transmission electron microscopy observations. After the 90% reduction due to cryorolling, the total volume fraction of α′-M reached 75.6%, and the average ultimate tensile strength (UTSav.) was significantly improved from 430.3 to 1306.8 MPa. Upon subsequent annealing at 923 K for 5 min, the tested alloy mainly consisted of a large number of fine grains and a few coarse grains (CGs). In addition, several deformed structures were also observed. As the annealing time increased to 10 and 30 min, the fraction of CGs increased, and a bimodal grain size distribution was obtained, while the deformed structures were still present. The temperature of the reverse phase transformation of α′-M → γ was lower than the recrystallization temperature, which may be the main reason for the bimodal grain distribution. With this bimodal grain structure, the alloy exhibited a combination tensile strength of 543.3 MPa and an average elongation of 34.1%.