ASTM E1820 Research Articles

Digital Image Correlation of Tensile Properties for Monel 400/SS 316L Dissimilar Metal Welding Joints.

Dissimilar metal weld joints of Monel 400 and Stainless Steel 316L stainless steel were carried out using Gas Tungsten Arc Welding (GTAW). Conventional annealing and cryogenic treatment were performed on the welded joints. Weld joints of this combination of materials have enormous potential applications in power industry and the available related literature is limited. In the present study, the tensile properties of heat treated (HT), cryotreated (CT), and untreated (UT) specimens were studied. The engineering stress and strain were determined experimentally as per Standard Test Methods for Tension Testing of Metallic Materials (ASTM E8). The strain distribution was evaluated at different zones of weld joint was evaluated using Digital Image Correlation (DIC). Significant difference was noticed between the zones. Weld zone of all samples had less local stress and strain and SS 316L heat affected zone (HAZ) zone had more local stress and strain when compared to other zones. The local strain distribution along distance from weld center line and local stress-strain curves of different zones are also predicted. Scanning Electron Microscopy was used to analyze the fracture behavior of welded samples for HT, CT, and UT specimens.

Monotonic and cyclic behavior of the nitrogen ion-implanted commercially pure-titanium

This research aims to study the behavior of monotonic and cyclic plastic deformation on commercially pure titanium which has undergone surface treatment using the nitrogen ion implantation method. The doses of 2.0×1017 ions/cm2 and the energy of 100 keV were used to implant the nitrogen ions into the CpTi. Monotonic properties tests were performed in a laboratory air and at room temperature using ASTM E8 standard specimens. Fatigue and corrosion fatigue tests were conducted in a laboratory air and in artificial saline solutions, at room temperature using ASTM 1801-97 specimens. Tensile tests were carried out with constant displacement rate and fatigue tests were carried under fully-reversed with stress-controlled conditions with stress amplitudes 230, 240, 250, 260, 270 and 280 MPa. The results showed the material properties of monotonic behavior for CpTi and Nii-Ti; tensile strength (σu) of 497 and 539 MPa and for 0.2% offset yield strength (σy) of 385 and 440 MPa, respectively and of cyclic behavior; cyclic strength coefficient (k’) of 568.41 and 818.64 and cyclic strain hardening exponent (n’) of 0.176 and 0.215, respectively. This study has succeeded in producing useful new material properties that will contribute to the field of material science and engineering.

Experimental investigation on Hydrogen embrittlement of EN47 Spring steel

Carbon steel is one of the significant engineering materials used in industrial and automotive sector. Most of the engineering metals are susceptible to hydrogen embrittlement (HE). It is an inherent phenomenon, which will occur during the course of service life and leads to pre mature failure of the component. In view of this, an experimental study was conducted to investigate the failure behavior of EN47 in a hydrogen simulated environment. The immersion type hydrogen charging method was adopted. The effect of HE was explored through conventional tensile testing. Experimentations were carried out according to ASTM E8 Standards. The tensile behavior of spring steel and effect of hydrogen interaction with materials was studied. The treated test material experience brittle to ductile transition exhibiting mixed mode fracture morphology on fracture surfaces, often considered being confirmation of failure through HE. Hydrogen charging causes the samples to become brittle, and reduced the plastic deformability. From the test results it can be interfered that the hydrogen charged specimen exhibits loss of ductility and also reduced the ultimate strength.

The effect of pouring temperature on the tensile strength and micro structure of Al alloys by centrifugal casting

There are many ways to overcome the leaking pipes in pipe joining; one of them is by using centrifugal casting as method for its production. The goal of this study is to know the effect of pouring temperature on the tensile strength and microstructure of centrifugal casted pipe product. We tried to produce the pipe at temperature of 680°C, 700°C and 720°C, with the constant rotation speed of the centrifugal casting machine (1500 rpm). The tensile test was done based on standard of ASTM E8. The results show that the highest tensile strength is obtained from the product that was manufactured at 680°C (136.3 MPa) and the lowest is at 720°C (115.3 MPa). These data are supported with the result of microstructure test which revealed that the amount of Al dendrite structure is more homogenous and uniform when the pouring temperature is closed to melting point.

Determination of Fracture Toughness and KIC-CVN Correlations for BM, HAZ, and WB in API 5L X60 Pipeline

This paper presents a study to determine the fracture toughness for the API 5L X60 pipeline in the base metal (BM), the heat-affected zone (HAZ), and the welding bead (WB) by SE(B) specimens in the short transverse direction in an API 5L X60 pipeline. Also, a comparison of the KIC results from SE(B) specimens and KIC-CVN (Charpy V-notch) correlation equations using CVN energy values was done. SE(B) specimens were machined and tested according to ASTM E339. Standard Charpy specimens were machined and tested according to ASTM E23. The notch remained within the evaluation zone to obtain KIC and Charpy specimens at the HAZ and WB. The KIC and CVN values are higher for the BM, followed by the HAZ and the WB. These KIC and CVN values are similar to those reported by other authors in API 5L pipelines. The decrease in KIC and CVN values is due to the microstructure present in the temperature transformations. For BM, the ferrite matrix with pearlite colonies could be presented, while for the WB zone, martensite and finer bainite are detected. In some regions of the HAZ temperatures are reached that promote the transformation of the ferritic/pearlitic structure of the BM into austenite. KIC-CVN correlation equations values should be used only to estimate KIC values when KIC data cannot be obtained from standard specimens.

Experimental investigation of scatter in fracture toughness data of SA516Gr.70 steel in the ductile-to-brittle transition regime for high rate of loading using split Hopkinson pressure bar test setup

Ferritic grade steels exhibit ductile to brittle transition in the sub-zero temperature regime and the fracture toughness data show scatter and temperature dependence. The fracture toughness variation also depends upon rate of loading in addition to neutron irradiation, specimen geometry and loading configuration. The material SA516Gr.70 steel is widely used in nuclear industry as material of transportation cask, vessels and piping etc. The study of the effect of rate of loading on the fracture toughness transition curve in the ductile-to-brittle transition regime of this material is important for designers and safety analysts. In this work, the split Hopkinson pressure bar test technique has been used to carry out fracture tests on sub-sized single-edged notched bend specimens in the temperature range of −100 to −60 deg. C by loading the specimens at a very high loading rate of 700 m/min. This loading rate is at least 6 orders of magnitude higher than the rates (i.e., fraction of mm/min) employed for quasi-static fracture tests. The strain pulses, during high rate of loading, have been captured through strain gages located in the incident and transmission bars of the test setup. The load–displacement data for the specimens have been evaluated from the strain signal and these have been used to evaluate fracture toughness for onset of cleavage fracture in terms of KJc. The scatter and temperature dependence of the data have also been modelled through Weibull’s statistical distribution and master curve bounds according to ASTM E1921. From the results of fracture experiments, it was observed that the fracture transition temperature T0 increased significantly for the high rate of loading when compared to quasi-static data of similar materials in literature. This observation has been explained in terms of micro-mechanism of the cleavage fracture in the process zone ahead of crack-tip which changes due to rate of loading. This study indicates that the rate of loading is an important parameter in the design and integrity analysis of ferritic grade steel components in addition to other parameters such as specimen geometry and loading conditions.

Mechanical properties and fatigue crack growth in tungsten deposited by RF-plasma

Fracture toughness and fatigue crack growth rates of free-standing thick W deposits produced in a protective atmosphere using radio frequency inductively-coupled plasma process were investigated. Stress-strain behavior of the deposits was studied using four-point bending and their fracture toughness was estimated from three-point bending following the ASTM E1820 standard. The fatigue crack growth rates were measured in symmetrical bending using a resonance approach. The results were compared with commercially available bulk tungsten prepared by powder metallurgy that served as a reference. The results showed that the deposits had significantly lower stress-strain properties: the elastic modulus and tensile strength ranged from 30% to 50% of the reference bulk values. The crack growth rate tests together with fractographic analysis suggested that a static failure by inter-granular decohesion predetermines the fatigue properties of the deposits and causes high slopes of the corresponding fatigue crack growth rate curves. Contrary to this, the reference sheet failed trans-granularly. The inter-granular failure mode of the deposits was caused by grain boundary embrittlement, a phenomenon probably related to oxides. The lowest obtained oxygen concentration in deposit was nearly by two orders of magnitude higher, than in reference sheet. The distribution of oxygen was studied by TEM and the amorphous and crystalline oxide phases were identified at splat interfaces. The presence of oxygen in the deposits produced by the inherently non-oxidizing RF technology calls for control of oxygen content in the feedstock powder. The performed characterization provided baseline data of mechanical and fatigue properties of RF plasma sprayed tungsten.

Experimental validation of miniaturized specimen developed to perform uniaxial tensile test on high performance materials

This work deals with the experimental validation of the proposed specimens geometries which design process through Finite Element Method was presented during AIAS 2019 and published afterwards [1]. In particular, non-conventional miniaturized specimen geometry compliant to ASTM E8 and ISO 6892, specifically developed to work with MaCh3D [2], an innovative miniaturized tensile testing machine, were considered. The size-reduction of specimens is advantageous both in terms of material and equipment: smaller specimens require lower forces to be broken, hence a compact tensile testing machine can perform the mechanical characterization activity. In this experimental validation, mechanical properties determined using the three proposed MaCh3D miniaturized specimens are compared to full-size ISO 6892 samples. Specimens were cut from AISI 304 stainless steel plates, with different thickness according to specimens requirements. Good accordance has been found between the standard and non-standard geometries.

Experimental Study on AA6005-T6 Material Welded with Friction Stir Welding Using Impact Test

The welding technique is often the choice in the joining process because of its light weight and relatively simple characteristics. Friction Stir Welding (FSW) is a welding method that was created and developed by The Welding Institute (TWI) in 1991. This easy, fast, and environmentally friendly welding process has been widely applied to construction, especially aluminum materials. The material used in the experiment was AA 6005-T6 6mm thick with varying tool speed parameters 765 1208 1907 3020 (rpm), feed rate 24 43 65 90 (mm/m), engine tilt, pin model (hexagonal, taper square, taper cylinder, cylinder), as well as an incision depth of 0.05 0.1 0.15 0.2 (mm). Using the Taguchy and ANNOVA methods as calculations and data processing. The test carried out is the impact test of the Charpy method using the ASTM E23 standard. After calculating with the Minitab 19 application, it was found that the most influential factor on the impact strength was the engine speed parameter of 765rpm which contributed 28.95%. Keywords: Welding Technique, Friction Stir Welding, Taghuchy, ANNOVA, impact test

A method for directly measuring fracture toughness and determining reference temperature for RPV steels by Charpy impact test

Accurately realizing the use of Charpy impact test to measure fracture toughness and determine reference temperature of low alloyed steel with ferritic microstructure has important practical engineering significance for the structural integrity assessment of reactor pressure vessels. In this paper, a methodology for measuring fracture toughness and determining reference temperature for RPV steels by Charpy impact test was proposed. The method referred to the ASTM E1820 and E1921 standard. By analyzing the physical meaning of the Charpy impact specimen’s fracture, load-time curve and size parameters, the fracture toughness of the material was directly calculated according to the linear elastic fracture mechanics. The reference temperature was calculated using the multi-temperature procedure formula. The reference temperature and fracture toughness were corrected according to two factors, such as the difference in fracture toughness caused by the difference in the loading rate of the stress intensity factor and the specimen shape and size between Charpy impact test and compact tension test. And the validity of the fracture toughness and reference temperature was evaluated. The corrected two are basically consistent with the data obtained by the compact tension test in accordance with ASTM E1820 and E1921 standards. This method may be used to solve the problem that the nuclear power plant needs to use the impact test data to evaluate the fracture toughness and reference temperature of the reactor pressure vessel in the structural integrity assessment of the reactor pressure vessel operation and life extension process.

Fracture Characterization of Base Metal, Seam Weld, and Girth Weld of Welded Line Pipe Steel at Room and Low Temperatures

For fitness-for-service assessment of pipeline cracks, it is necessary to examine toughness values of pipeline steels and their variations with temperature. In this study, experimental values of toughness (KJC) at room temperature have been obtained for base metal (BM), seam weld (SW), and girth weld (GW) in an API X65 gas transportation pipeline in order to investigate the structural integrity of whole structure. The toughness tests employed side-grooved compact tension specimens, obtained from the original pipe, to characterize the resistance to crack extension curves based on the unloading compliance technique. The values of JIC for tested specimens were found, and then, KJC values are obtained using ASTM E1820 guideline as 302, 262, and 166 MPam1/2 for BM, SW, and GW materials, respectively. Charpy V-notch (CVN) impact tests at room and low temperatures were also conducted to determine low-temperature effects on the toughness, and to examine ductile–brittle transition temperature values in the samples under study. The capability of CVN test for prediction of toughness in the tested specimens was also investigated. The error values in using CVN test results are large enough to justify that the CVN test is not suitable for prediction of toughness accurately.

Fracture-mechanical properties of neutron irradiated ITER specification tungsten

The work focuses on the investigation of the influence of neutron irradiation on the fracture mechanical properties of ITER specification-conform, stress-relieved tungsten bar. The irradiation of miniaturized Three-Point Bend specimens was performed inside the fuel channel of the Material Test High Flux BR2 reactor of SCK•CEN in Mol. An irradiation damage dose close to 1 dpa (in tungsten) was achieved at 800°C with active temperature cooling and constant on-line temperature monitoring. Thick-wall stainless steel capsules were implemented for shielding the thermal neutrons in order to reduce Re transmutation down to ~2 at.% (and 0.2 at.% Os). The quasi-static fracture mechanical experiments were carried out following ASTM E399 aiming at the determination of plane strain fracture toughness KIc. The post irradiation examination of the specimens irradiated at 800°C reveals severe material embrittlement. At Ttest = Tirr = 800°C, a deformation free brittle fracture is observed. The fractographic investigations show a mixture of brittle transgranular cleavage and intergranular fracture. With increasing the test temperature above 1000°C, the fracture mode is changed from the brittle to a ductile one. Blunting of the notch tip leads to a suppression of the crack initiation and propagation and consequently no failure of the specimens was observed up to severe deflection levels. In some cases, however, a ductile crack growth with a characteristic dimple formation was identified, in addition. Based on the obtained results, the Ductile to Brittle Transition Temperature shift induced by the neutron irradiation at 800°C is evaluated to be 600-625°C.

ASTM E399「線形弾性平面歪破壊靱性の標準試験法」に関する最近の動向

ASTM E399「線形弾性平面歪破壊靱性の標準試験法」に関する最近の動向

The mechanical properties and microstructure behavior of aluminium alloys subjected to shock waves

The present study involves the study of mechanical properties such as hardness, Tensile strength and micro structure analysis. In first stage the above properties are experimentally determined for aluminium alloy without subjected to shockwaves .In second stage the specimen are subjected to shockwaves of different frequency, after the above mentioned properties are determined. Finally comparative study has been carried out to know the effect of shockwaves on the mechanical properties and microstructure. Experimentation is conducted for different frequency of shockwave. Reddy shock tube is used to produce shockwave with a Mach number of Maximum 7. Due to the application of shockwave on the surface of aluminium alloy, change in the mechanical and microstructure properties. It is observed that there an increases hardness and decrease tensile property and uniform Distribution of alloy elements. Here shockwave is applied on aluminium alloy AA6063 with the pressure ranging from 2 to 6 bar by using of Reddy shock tube. Specimen have 150 mm*150 mm sheet, of 3 mm thickness is subjected to shockwave for different pressure. Shockwave produced is propagated in driven section is record through oscilloscope. Specimens are prepared as per ASTM E8 and E10 standard. After experiment hardness test, tensile test and microstructure analysis has been carried out. The results indicates that, there is an effect of shockwave on mechanical properties and change in microstructure. Which shows that there is enhancement of the properties of alloy.

Study of geometric parameters and TiC reinforcements in aluminium metal matrix composite on fracture toughness using Taguchi method

In aluminum alloy, Titanium carbide (TiC) reinforcements act as nucleation sites and refine grain structure during solidification. Al-TiC particulate composites find major applications in structural and automobile parts due to their attractive features such as high elastic modulus and hardness. Therefore, attempts are made in the present work to know the fracture behavior of metal matrix composites prepared with varied fraction of reinforcement particles (3 wt%, 5 wt%, 7 wt% of TiC) under various notch sizes of the compact tension (CT) specimen. Al6061-TiC MMCs compact tension specimens are prepared as per ASTM E399 standards, to examine the fracture toughness (KIC). The CT specimens are machined to obtain the desired geometry i.e. crack to width (a/W) ratio of 0.3, 0.4 and 0.5 and thickness to width (B/W) ratio of 0.3, 0.4, and 0.5. Taguchi L9 orthogonal array experiments are conducted to study the effect of the factors (TiC reinforcements, a/W and B/W) on the performance of fracture toughness of the composites. The contribution of each factor is evaluated on the fracture toughness of Al6061-TiC composites. The maximum values of fracture toughness was observed for the optimized set of Al6061-TiC (3 wt%), a/W ratio and B/W ratio maintained equal to 0.4. Taguchi method results could help any novice user in obtaining the optimum fracture toughness without much efforts, materials and time.

Influence of Immersion Corrosion on Mechanical Properties of AISI 430/AISI 316L Dissimilar Welded Joints

Dissimilar welded joints of AISI 430 and AISI 316L stainless steel were produced by the GMAW process using two different shielding gas mixtures composed of 97Ar-3N2 and 80Ar-19He-1O2. The microstructure of the heat-affected zone was characterized by optical and scanning electron microscopy, and Vickers microhardness measurements were carried out along the cross-section of the specimens. The dissimilar welded joints were submitted to immersion corrosion test in a 10%v/v hydrochloric acid solution for 24 and 72 hours. Afterward, yields strength, tensile strength, and elongation percentage were measured using tensile tests according to ASTM E8 standard. Non-immersed welded joints were used for comparison purposes. An analysis of variance was developed to evaluate the influence of immersion time and shielding gas mixture on yielding strength and tensile strength. The microstructure characterization showed that the heat-affected zone on AISI 430 side was the widest, and it was observed a significant presence of acicular ferrite, martensite, and coarsened ferritic grains. In contrast, on the heat-affected zone on AISI 316L side was not observed coarsening nor refinement of austenite grains. The AISI 430 heat-affected zone showed the maximum hardness values and higher susceptibility to corrosion damage. Tensile tests results evidenced that immersion corrosion tests did not change significantly ultimate strength in comparison to non-immersed specimens while yielding strength and elongation percentage were drastically decreased due to immersion time. According to the p-value, the immersion time is the most influencing factor on yielding strength and tensile strength of the dissimilar welded joints.

Mechanical characterization of graphene-aluminum nanocomposites

Abstract As we know that present demand of materials having high strength, stiffness, wear resistance, toughness, and less dense properties for their wide application in electrical wire, automotive and aerospace parts. Graphene based aluminium metal matrix nanocomposite (Gr/AL) have huge potential for these applications. Gr/AL nanocomposites are made up of combining two constituent materials (Graphene and Aluminium). The metal matrix composite are composite in which metal is used as a matrix phase. If the composites have more than two constituent materials then it is called the hybrid composite. In this paper Aluminium Alloy 2024 has been used as matrix material and Graphene is to be taken as the reinforcing element. The nanocomposite has been prepared by Stir casting method. The casted product is machined to required ASTM E8: B557 standard and characterization is done for the tension, compression, hardness and microscopic properties.

Experimental and finite element analyses for residual stress prediction of welded SAE-1018 steel joints

Welded joints are a critical part of any structural component, and the stresses induced can cause a major problem in structural integrity. The presented work discusses the development of a numerical model using finite element techniques to determine the residual stress of an SAE-1018 welded joint. A 3D thermo-mechanical coupled model for shielded metal arc welding is developed to predict the tensile and compressive residual stresses. Further, a uniaxial tension test is also modelled to predict the weld joint strength, and the numerical results are validated with the experiments. ASTM E8 standards are used to perform the tensile test.

A study of tensile behavior of SLM processed 17-4 PH stainless steel

This study provides an insight into the comparison of the tensile properties between 17-4 PH SS samples processed by Selective Laser Melting (SLM) and the wrought 17-4 PH samples. The tests were conducted according to the international standard ASTM E8 and the microstructural studies were also performed. The SLM built part revealed superior tensile properties against the wrought sample. Furthermore, the SLM processed sample displayed significantly higher ductility and ultimate tensile strength (UTS) with respect to wrought samples. The microstructure of the SLM-built samples showed higher proportion of retained austenite compared to wrought samples.

Effect of Heat Treatment and Cryotreatment on the Fatigue Crack Growth in Aluminium 7075 Alloy

Al 7075 is an aluminium alloy with zinc as major element. Al 7075 is commonly used in aircraft components, especially for critical parts like wing and fuselage components. In present investigation Al 7075 has been selected subjected to annealing, cryogenic treatment and the combination of annealing and cryogenic treatment for the study of fatigue crack growth subjected to fatigue load at constant amplitude. Specimens were subjected to fatigue crack growth as per ASTM E-647 standards and the results of fatigue crack growth were compared. NASGRO software was used to predict the fatigue crack growth (FCG) and the results are validated using experimental results. Microstructure analysis of metallic specimens was also carried out to study the micro structural changes in specimens undergoing heat treatment and cryotreatment. From the present investigation it has been observed that cryogenic treatment and heat treatments plays vital role in improving fatigue life of Al 7075 components.