Maximum Tensile Shear Strength Research Articles

Microstructure, tensile and fatigue properties of ultrasonic spot welded aluminum to galvanized high-strength-low-alloy and low-carbon steel sheets

The microstructure evolution, tensile lap shear strength and fatigue properties of dissimilar ultrasonic spot welded (USWed) joints of aluminum to two commercial steel sheets at different welding energies were investigated. The main intermetallics at the weld interface were θ (FeAl3) in both joints along with eutectic Al-Zn in Al-to-galvanized high-strength-low-alloy (HSLA) steel joints and Fe3Al in Al-to-ASTM A36 steel joints. The welding strengths of both joints were higher than those of other dissimilar joints reported in the literature. With increasing welding energy, the maximum tensile lap shear strength increased in the Al-to-galvanized HSLA steel joints, while the lap shear strength increased up to a peak value and then decreased in the Al-to-ASTM A36 steel joints. Both the average peak welding strength and fracture energy of the Al-to-galvanized HSLA steel joints were higher than those of the Al-to-ASTM A36 steel joints. The fatigue lives of both welded joints were in agreement with or somewhat longer than other Al-to-steel USWed joints in the literature. The fatigue fracture mode changed with increasing cyclic loads in both welded joints. Fatigue crack growth was mainly characterized by the formation of fatigue striations perpendicular to the fatigue crack propagation direction.

Resistance spot weldability of lightweight steel with a high Al content

Using alternating current (AC)- and direct current (DC)-type welders, the resistance spot weldability of lightweight steel was evaluated under various electrode forces, welding currents, and times. The acceptable welding conditions were specified; however, these had very narrow ranges and there was little difference between the conditions determined for the AC- and DC-type welding. In both types of welding with electrode forces of of 300 kgf and 400 kgf, the acceptable weld currents were 5.0 kA and 5.5 kA, respectively. Also, the nugget size increased with the welding current. Under the acceptable welding conditions, there were no significant changes in the maximum tensile shear strength and nugget size, as 6.4-6.6 kN and 4.1-4.3 mm, respectively. The microstructure of weld metals was consisted of martensite, austenite and ferrite. And the small fraction of martensite was founded in the heat affected zone (HAZ), therefore the weld metal had the greatest hardness, and HAZ softening did not occur in this study. Considering the fracture surface, cleavage and ductile fracture were investigated because of the existence of martensite and ferrite in the welds.

Ultrasonic Welding of Bi-Metals: Optimizing Process Parameters for Maximum Tensile-Shear Strength and Plasticity of Welds

The recent drive towards lightweight construction in the aerospace and automotive industries has been increased tremendously. Hence, suitable joining methods are necessary in order to reliably join materials like aluminium, copper etc., and to integrate them in engineering structures. Ultrasonic welding is a rapid manufacturing solid-state joining process that produces joints by the application of high frequency vibratory energy in the work pieces held together under pressure. It is a combination of both surface (friction) and volume (plasticity) softening effects. In this paper an effective methodology is developed to determine the optimum welding condition that maximizes the strength of the welded joints produced by ultrasonic welding by using Taguchi method. This method has been utilized to develop an effective model to predict weld strength by incorporating process parameters such as weld time, pressure and amplitude. Experiments were performed on bi-metals i.e. aluminium and copper of 0.5mm thickness specimen and an effective S/N ratio graphs were plotted with ANOVA for the inference to optimum result for Tensile-Shear strength.

Microstructure and mechanical properties of laser welded-brazed Mg/Ti joints with AZ91 Mg based filler

AZ31B Magnesium (Mg) alloys and Ti-6Al-4V titanium (Ti) alloys were joined by laser welding-brazing process with AZ91Mg based filler. Uniform and continuous weld surfaces without obvious defects were produced in a relatively large processing window. In the process Al element diffused from the filler and reacted with Ti resulting in metallurgical bonding of Mg/Ti joint. An ultra-thin reaction layer with serrate-shaped morphology was evidently observed at the interface of AZ91 fusion zone/Ti. The thickness was varied slowly with the change of the heat input. Newly formed interfacial compound was then identified as Ti3Al phase by transmission electron microscopy (TEM) analysis. The maximum tensile-shear strength reached 2057N, representing 50% joint efficiency relative to Mg base metal. Two kinds of fracture modes were noticed during the tensile-shear test. Observation of fracture surfaces suggested some reaction products were attached to Ti substrate in both cases, which was found to prevent crack propagation effectively and thus improved the joint strength.

Effect of Resistance Spot Welding Parameters on AA1100 Aluminum Alloy and SGACD Zinc coated Lap Joint Properties

This article is aimed to study the effects of resistance spot welding (RSW) on the lap joint properties between AA1100 aluminum alloy and SGACD zinc coated steel and its properties. The summarized experimental results are as follows. The summarized experimental results are as follows. The optimum welding parameters that produced maximum tensile shear strength of 2200 N was a welding current of 95 kA, a holding time of 10 cycles, and a welding pressure of 0.10 MPa. Increasing of welding current, increased the tensile shear strength of the joint and also increased the amount of aluminum dispersion at the joint interface. The lap joint of steel over the aluminum (Type I) showed the higher joint tensile shear strength than a lap joint of aluminum over the steel (Type II). The indentation depth and the ratio of the indentation depth to the plate thickness decreased when the welding current was increased in the type I lap joint and also decreased when the welding current was decreased in the type II lap joint. The interface structure showed the formation of the brittle <TEX>$FeAl_3$</TEX> intermetallic compound that deteriorated the joint strength.

Microstructure and mechanical properties of tungsten inert gas welded–brazed Mg/Ti lap joints

The tungsten inert gas (TIG) welding–brazing technology using Mg based filler was developed to join AZ31B Mg alloy to TA2 pure Ti in a lap configuration. The results indicate that robust joints can be obtained with welding current in the range of 60–70 A and welding speed of 0·2 m min−1. The joints were found to be composed of the coarse grained fusion zone accompanied with the precipitated phase of Mg17Al12, and a distributed Mg–Ti solid solution zone at the interface of Mg/Ti, indicating that metallurgical bonding was achieved. The maximum tensile–shear strength of 193·5 N mm−1, representing 82·3% joint efficiency relative to the Mg alloy base metal, was attained. The optimised Mg/Ti joint fractured at Mg fusion zone upon tensile–shear loading, mainly caused by grain coarsening. Moreover, the fracture surface practically consisted of scraggly areas, which was characterised by equiaxed dimple patterns accompanied with a few lamellar tearing.

Microstructure and Mechanical Property Analyses of Brazing Titanium and Low Carbon Steel Using Silver-Based Brazing Alloy

Brazing of commercially pure titanium to low carbon steel by using the Ag72Cu28 interlayer at different conditions was carried out in the present work in order to investigate the tensile-shear strength, microstructure and the fracture morphology of brazed joint. The results show that different intermetallic compounds such as CuTi,CuTi2,Cu4Ti3 and FeTi were formed at the bonding area. It was observed that the microstructure of joint has a considerable effect on tensile-shear strength of the brazed samples and the maximum tensile-shear strength was achieved at “750°C-10min→850°C-5min”.All the fracture paths after tensile-shear tests occurred in the interface between titanium and silver-based interlayer in spite of the different fracture morphology.

Correlation analysis of the variation of weld seam and tensile strength in laser welding of galvanized steel

Many advantages of laser welding technology such as high speed and non-contact welding make the use of the technology more attractive in the automotive industry. Many studies have been conducted to search the optimal welding condition experimentally that ensure the joining quality of laser welding that relies both on welding system configuration and welding parameter specification. Both non-destructive and destructive techniques, for example, ultrasonic inspection and tensile test are widely used in practice for estimating the joining quality. Non-destructive techniques are attractive as a rapid quality testing method despite relatively low accuracy. In this paper, we examine the relationship between the variation of weld seam and tensile shear strength in the laser welding of galvanized steel in a lap joint configuration in order to investigate the potential of the variation of weld seam as a joining quality estimator. From the experimental analysis, we identify a trend in between maximum tensile shear strength and the variation of weld seam that clearly supports the fact that laser welded parts having larger variation in the weld seam usually have lower tensile strength. The discovered relationship leads us to conclude that the variation of weld seam can be used as an indirect non-destructive testing method for estimating the tensile strength of the welded parts.

Research on key influence factors of laser overlap welding of automobile body galvanized steel

In views of structure characteristics of the auto-body parts, the influences of the beam incident angle and joint gap on the performance of laser overlap welded joints were investigated. The experimental results indicate that there were the critical values of beam incident angle and joint gap during laser overlap welding of galvanized steel. The thickness of sheet and the width of joint had a certain influence on the critical beam incident angle and the limit joint gap. With regard to thicker sheet, the limit joint gap can increase appropriately, but the critical beam incident angle should not be too big. With narrow weld width, the laser beam incident angle can increase appropriately, but the joint gap should not be bigger. Additionally, the critical beam incident angle and the limit joint gap were varied with the thickness of the upper sheet. The tensile-shear tests show that the maximum tensile-shear strength of the joint can be obtained with an optimized beam incident angle and joint gap.

Influence of Zn Coating on Interfacial Reactions and Mechanical Properties During Laser Welding-Brazing of Mg to Steel

To investigate the influence of Zn coating on the joining of magnesium alloy AZ31 to Zn-coated steel, dissimilar metal joining both with and without Zn coating was performed by the laser welding-brazing (LWB) process. Welding characteristics including joint appearance, identification of interfacial reaction layers, and mechanical properties were comparatively studied. The results indicated that the presence of Zn coating promoted the wetting of liquid filler wire on the steel substrate. Heterogeneous interfacial reaction layers formed along the interface between the Mg alloy and Zn-coated steel, whereas no distinct reaction layer and increased concentration of Al were identified at the interface between the Mg alloy and noncoated steel. The maximum tensile-shear strength of Mg/steel lap joint with Zn coating reached 180 N/mm, which was slightly higher than that achieved without Zn coating (160 N/mm). Failure of joint in both cases occurred at the interface; however, the fracture mode was found to differ. For Zn-coated steel, the crack propagated along the Mg-Zn reaction layer and Fe-Al phase, with little Mg-Zn reaction phases remaining on the steel side. As for noncoated steel, some remnants of the seam adhered to the steel substrate.

Optimization of Tensile-Shear Strength for Linear Welded Scots Pine

The mechanical performance of welded wood has a decisive role in its applications. This study was performed to determine the welding conditions that optimized the tensile-shear strength of welded Scots pine (Pinus sylvestris). Tensile-shear strength as a function of welding pressure, welding time and holding time was measured according to European standard EN 205. Maximum tensile-shear strength of welded sample was 9.3 MPa that was obtained using 1.3 MPa welding pressure, 2.8 s welding time and 70 s holding time. This tensile-shear strength was about two times that of PVAc-glued samples. According to data evaluation tensile-shear strength could be optimized to 9.7 MPa by increasing the welding time to 3.5 s and decreasing the holding time to 60 s.

Investigation on Joining Mechanism of SiC Particle Reinforced Aluminum Matrix Composite (Al/SiCp-MMC) by Resistance Spot Welding

The present study had investigated the joining performance of SiC particle reinforced aluminum metal matrix composite (Al/SiCp-MMC) having 1.0mm thickness by resistance spot welding processes. The welded joints were subjected to tensile-shearing tests in order to determine the strength of the welded zone. In addition both scanning electron microscopy (SEM) and optical microscopy (OM) were conducted to investigate the micro structural and micro hardness’s changes of the welded joints. The results reveal that: the maximum tensile-shear strength value of welded joint was obtained in these optimum welding parameters as in 17.5kA welding current for 60 periods welding. The electrode pressure was 3.5kN. It was favorable to select relatively high welding current and short welding time for improving mechanical properties of spot welded SiCp/LY12 composite joint. In this base, the welding mechanism of resistance spot welding SiCp/LY12 composite has also been discussed in detail.

Development of response surface model for tensile shear strength of weld-bonds of aluminium alloy 6061 T651

The development of a response surface model to study the influence of process parameters of weld-bonding on tensile shear strength of the weld-bond of 2 mm thick aluminium alloy 6061 T651 sheets has been reported. Significant and controllable process parameters of the weld-bonding (surface roughness, curing time, welding current, welding time and electrode pressure) and their ranges were identified by conducting pilot experiments. Welding current, welding time and welding pressure were identified as significant and controllable parameters. Influence of the significant process parameters and their interaction on the tensile shear strength of the weld-bonds was studied using response surface methodology (RSM). Using model, the optimal combination of weld bonding process parameters for maximum tensile shear strength of the weld bond was obtained. The validity of the model was evaluated on weld bonds developed using different levels of process parameters and testing their tensile shear strength. The model error was found to be in a range of 3–7%.

Fabrication and mechanical properties of UV-curable glass fiber-reinforced polymer—matrix composite

A UV-curable glass fiber-reinforced composites was investigated in order to develop a cost-effective fabrication approach for manufacturing polymer—matrix composites. The effects of glass fiber-treating process and UV exposure power on the tensile strength were studied through scanning electron microscopy, contact angle determination, and curing degree test. The experimental results showed 11.5% increase in tensile strength for the UV-cured composite reinforced with heat-treated glass fiber, and 51.4% increase with glass fiber treated by coupling agent. The optimal exposure power was 0.94 J/mm2 to obtain the optimized mechanical properties. However, overexposure could seriously result in the loss of tensile strength. The maximum tensile strength and shear strength of composite cured by UV approach in this study were 902.09 and 25.04 MPa, respectively.

A newly developed tool without probe for friction stir spot welding and its performance

A newly developed tool for friction stir spot welding (FSSW) has been proposed, which has no probe, but a scroll groove on its shoulder surface (scroll tool). By use of this tool, FSSW has been performed on aluminium alloy 6061-T4 sheets and the potential of the tool was discussed in terms of weld structure and static strength of welds. The experimental observations showed that the scroll tool had comparable or superior performance to a conventional probe tool. It was confirmed that sound welding could be achieved without a probe hole, in which the scroll groove played significant roles in the stirring of the material and the shoulder plunge depth was the important processing variable. The maximum tensile-shear strength of the welds made by the scroll tool was found to be 4.6 kN that was higher than that of the welds made by the probe tool and two different fracture modes, shear fracture and plug fracture, appeared depending on processing condition. The shear fracture took place at smaller shoulder plunge depths or at shorter tool holding times, while the plug fracture occurred at larger shoulder plunge depths or at longer tool holding times. It was indicated that the tensile-shear strength and associated fracture modes were determined by two geometrical parameters in the weld zone.

Weldability and mechanical properties of dissimilar aluminum–copper lap joints made by friction stir welding

Lap joints of 1060 aluminum alloy and commercially pure copper was produced by friction stir welding and the effect of welding speed on interface morphology, microstructure, and joint strength was investigated. The experimental results revealed that in the aluminum close to the Al/Cu interface, a dark area was formed. In this area the intermetallic compounds of Al 4 Cu 9 and Al 2 Cu, and some microcracks were detected. The frequency of such microcracks decreased with increasing welding speed. On the other hand, at higher welding speeds of 118 and 190 mm/min, the cavity defects were formed inside the joints as a result of insufficient heat input. The results of tensile shear test revealed that the maximum tensile shear strength of joint was obtained at welding speed of 95 mm/min. At this welding speed, no cavity defects, and few microcracks were observed in the weld.

Characteristics of adhesive joints of metals using inorganic particulate composite adhesives

The characteristics of adhesive joints of similar sheets of aluminium and steel containing epoxy based particulate composite adhesives have been studied. The composite adhesives having particulate fillers as aluminium and alumina powders of varying amount (5–15wt.%) and size (75–84 to 0.8–1.2 mm) are applied to mechanically and chemically treated aluminium and mechanically treated steel substrates. The joints of the composite adhesive are characterized by their tensile lap shear strength as a function of the bond-line thickness as well as the amount, size and type of particle. For a given substrate the characteristics of the composite adhesive joint have been compared to those of the conventional adhesive joints. The bond-line thickness of the adhesive with respect to the amount and size of the aluminium and alumina particles has been optimised for maximum tensile shear strength of the adhesive joint of differently treated substrates.

Influence of Electrode Pressure and Welding Conditions on the Maximum Tensile Shear Load-Study on the Development of Electrode Force Changeable Lap Resistance Spot Welding Machine and Characteristics of Welds (Report 2)-

Lap resistance spot welding was performed on cold rolled steel (SPCC) with an electrode force changeable lap resistance welding machine the authors had developed. We evaluated the welds by ultrasonic testing (immersion method, C-scope representation) and a tensile shear test, and compared the results for this method with those by the conventional method. It was useful to apply the ultrasonic testing to evaluate the welds. Usually plug-type fracture was observed in the tensile shear test and the maximum tensile shear load was larger than those estimated using the value of the minimum strength (290 MPa) of SPCC specified by the Japanese Industrial Standard, though some specimens fractured along the weld interface. Regression analysis was performed by setting the maximum tensile shear load as a dependent variable, and setting the initial electrode force, the welding current, the initial electrode force timing and the latter electrode force as independent variables. The result shows that only the initial electrode force and the welding current were significant. The maximum tensile shear strength increased by increasing the welding current and decreasing the initial electrode force. It was made clear that we could obtain better spot welds by using the process we developed than the conventional spot welds.

Thermoplastic Epoxide Resin in the Presence of Polyethylene Glycol as Hot-melt Adhesive in Clean Technology

Pollution caused by the process involving handling of solvents is considered as one of the most serious ecological problems. In this perspective, thermoplastic epoxide resins were synthesized from the controlled reaction of bisphenol A, epichlorohydrine, and 3,5 dimethylaniline with a view to prepare ingredients for hot melt adhesive) was designated as HMA/(Subscript)35' Addition of polyethylene glycol (20 Wt per cent) of molecular weight 6000 (PEG6K) in the blend was found to be optimum towards providing maximum tensile lap shear strength with reference to aluminium/adhesive/aluminium bonding with a value of 5.05MPa. The matrix of the blend remains optically transparent till the content of PEG6K remains up to 20 Wt per cent; however beyond 20 Wt percent of PEG6k, the matrix becomes opaque with the appearance of spherulities due to presence of excess PEG6K in the blend. Interestingly, blends containing <= 20 Wt percent PEG6K showed no endotherm below 100 (Degree)C even though the melting point of pristine PEG6K is 55 (degree)C. FTIR data revealed the interactive role of PEG6K with the epoxide resin.

203 鋼-アルミ合金のレーザによる異材接合(OS 溶接・接合)

Dissimilar joint of steel and aluminum alloy was produced by YAG laser welding. Maximum tensile shear strength was about 86 % of tensile strength of aluminum alloy. About 10 μm thickness intermetallic layer was observed at the interface of the joint. Temperature distribution was calculated by BEM (Boundary Element Method) analysis combined with the results of temperature measuring test. According to BEM analysis, maximum temperature at the interface was between melting point of aluminum and steel. Diffusion occurred during laser welding between solid state steel and liquid state aluminum to produce thin intermetallic layer