As-received Condition Research Articles

Microstructure and texture of high manganese steel subjected to dynamic impact loading

ABSTRACT Dynamic impact response of high Mn-steel at a strain rate of 3000 s−1 was investigated using the Split Hopkinson Pressure bar. The investigated steel depicted continuous yielding at high strain rates. Additionally, the yield stress displayed a positive strain-rate sensitivity with an increasing strain rate. Microstructural evaluations displayed that strain-induced martensitic transformation and dislocation multiplication during slip were dominant plastic deformation mechanisms in the absence of deformation twinning which contributes to the strain hardening. Adiabatic shear band and martensite to austenite reversion or dynamic recrystallisation were also attributed to strain softening during impact deformation. The {001}<110> R-cube, {011}<110> R-Goss, and ({111}<110>) E texture components were strengthened after impact loading compared with as-received condition, while the intensities of Cube, Cupper, Brass, and S texture components were decreased.

Spectroscopic Analysis of Irradiated Natural Quartz and ESR dating aspects

Abstract In this study, we conducted a spectroscopic characterization of natural milky quartz sample from Wadi Araba at the Egyptian Eastern Desert. This quartz material had been studied using scanning electron microscope (SEM), X-ray powder diffraction (XRD), UV–visible spectrophotometer (UV–vis), Fourier transform infrared spectrometer (FTIR), X-ray fluorescence spectrometer (XRF), inductively coupled plasma optical emission spectrometer (ICP-OES) and electron spin resonance (ESR) technique. In the current study, we have used raw samples as-received and gamma-irradiated conditions. The results reviled that gamma radiation had a slight influence on the color of milky quartz samples. XRF and inductively coupled plasma optical emission spectrometer were used to recognition the elemental composition of the raw sample. The ESR spectrum accomplished at room temperature display intrinsic defects such as Aluminium (Al) trap center. Furthermore, with increasing the additive doses the area under the dose response curve increases as a polynomial function, which applicable for ESR dating aspects.

Evaluation of titanium dioxide coating on surface roughness of nickel-titanium archwires and its influence on Streptococcus mutans adhesion and enamel mineralization: A prospective clinical study

This research aimed to evaluate the effect of titanium dioxide (TiO2) coating on surface roughness (Ra) of nickel-titanium (NiTi) archwires and its influence on Streptococcus mutans (S mutans) adhesion and enamel mineralization at the end of 1month in orthodontic patients and to evaluate the integrity of the TiO2 coating. Twelve patients undergoing orthodontic treatment with preadjusted edgewise appliance formed the sample for this prospective clinical study. Uncoated NiTi archwires and TiO2 nanoparticle coated NiTi archwires in as-received condition and after 1month of intraoral use were subjected to Ra analysis using surface profilometry, and surface topography using scanning electron microscopy. S mutans adhesion was evaluated on the retrieved archwires using real-time polymerase chain reaction (PCR). Enamel mineral content in the arches related to the uncoated and coated archwires was evaluated using DIAGNOdent. After 1month of intraoral use, both coated and uncoated archwires exhibited a rougher surface with coated archwires demonstrating greater quantum of increase (control, P=0.002; experimental, P=0.002). S mutans adhesion was more in uncoated archwires (P=0.0005). The TiO2 nanoparticle coating on the NiTi archwires showed delamination, deterioration and was lost by 60% at the end of 1month. Laser fluorescence values did not show any significant difference (control, P=0.182; experimental, P=0.105). TiO2 nanoparticle coating on NiTi archwires causes an initial reduction in roughness; however, at the end of 1month, the benefit was lost. S mutans adhesion was lesser on the coated wires, which could be attributed to reduced initial Ra and antibacterial property of TiO2. Orthodontic archwire appears to have a limited role in enamel demineralization.

Influence of Impact Velocity on the Residual Stress, Tensile Strength, and Structural Properties of an Explosively Welded Composite Plate.

This study aimed to analyze the effect of the impact velocity of a Zr 700 flyer plate explosively welded to a Ti Gr. 1/P265GH bimetallic composite on the residual stress formation, structural properties, and tensile strength. The residual stresses were determined by the orbital hole-drilling strain-gauge method in a surface layer of Zr 700 in as-received and as-welded conditions. The analysis of the tensile test results based on a force parallel to interfaces was used to propose a model for predicting the yield force of composite plates. Compressive residual stresses found in the initial state of the Zr 700 plate were transformed to tensile stresses on the surface layer of the welded Zr 700 plate. A higher impact velocity resulted in higher tensile stresses in the Zr 700 surface layer. To increase the resistance of the composite plate to stress-based corrosion cracking, a lower value of impact velocity is recommended in the welding process.

Effect of Thermo-mechanical Treatment on High Temperature Tensile Properties and Ductile–Brittle Transition Behavior of Modified 9Cr-1Mo Steel

In the present work, a modified 9Cr-1Mo steel is subjected to normalizing and tempering treatment with or without an intermediate rolling, which was carried out at 1050 °C in austenitic phase and 550 °C in metastable austenitic phase. The tempering was carried out at 700 °C and 750 °C to improve the strength by precipitation hardening and refining the microstructure. The ductile to brittle-transition temperature (DBTT) and tensile properties have been evaluated at 20 °C, 550 °C and 650 °C for the material subjected to various thermomechanical treatments. Rolling performed in austenitic phase showed improvement in the upper shelf energy and reduction in the DBTT compared with the material rolled in metastable austenitic phase. Rolling in metastable austenitic phase improved the yield strength at elevated temperature (39 pct at 20 °C, 31 pct at 550 °C and 91 pct at 650 °C) and was accompanied by a reduction in ductility (21 pct at 20 °C, 32 pct at 550 °C and 35 pct at 650 °C) compared with the as-received condition. The influence of grain size, low angle boundaries and precipitates on DBTT and high temperature strength has been studied using EBSD and TEM analyses. An increase in high temperature strength is found to increase with the area fraction of fine M23C6/MX precipitates, whereas low angle boundaries and effective grain size influenced the DBTT behavior. The combined effect of precipitation strengthening and strain hardening leads to improvement in the high temperature mechanical strength while maintaining adequate toughness. The effect of aging (for 72 hours at 650 °C) on heat-treated and -rolled samples showed a small decrease in yield strength at 20 °C. A decreasing trend of fracture toughness is observed with the increase in yield strength.

Evaluation of friction welded dissimilar pipe joints between AISI 4140 and ASTM A 106 Grade B steels used in deep exploration drilling

In the present research work, a detailed evaluation of dissimilar friction welded joints between the hot rolled ASTM A106 Grade B (carbon steel) pipes and hot rolled AISI 4140 (low alloy steel) pipes in the as-received (AR) condition and quenched and tempered (QT) condition has been carried out. All the specimens were subjected to stress relief annealing after welding. Optical and scanning electron microscopy on the AISI 4140 steel side revealed dynamically recrystallized grains, consisting of a mixture of ferrite and martensite in the friction welded AR-condition joints and mixture of ferrite and tempered martensite in the friction welded QT-condition joints. On the ASTM A 106 Grade B steel side the material showed ferrite and pearlite microstructure. SEM analysis did not reveal any intermixing between AISI 4140 and ASTM A106 Grade B steels at the weld interface in both the conditions. The region adjacent to the weld interface on AISI 4140 steel side consistently showed higher hardness in the QT-condition compared to AR-condition due to the presence of fine-grained microstructure in QT-condition. The dissimilar welded pipe joints in the present study have shown slightly higher tensile properties than that of ASTM A106 Grade B steel but significantly lower than that of AISI 4140 steel. The friction welded dissimilar pipe joint specimens have shown substantially lower impact toughness values compared to either ASTM A 106 Grade B steel or AISI 4140 steel in both AR and QT-conditions due to the presence of carbides at the weld interface.

Influence of Load, Surface Finish and Lubrication on Friction Coefficient of AISI 304 Stainless Steel

The present work aims to evaluate the friction and wear behavior of a metastable stainless steel AISI 304L against steel AISI 52100 ball. Friction tests using the “ball-on-disc” technique at constant velocity (0.03 m/s) and different loads (6 N, 15 N) with and without lubricant (liquid vaseline) were carried out. Two surface finishing conditions were considered, leading to different mixture phases of preexisting austenite and martensite in the steel. One set of samples was polished to induce martensite (PO), and another set was tested in the as-received (AR) condition. Special emphasis was placed on correlating the friction and wear behavior with microstructural analysis performed by x-ray diffraction, optical, scanning electron and transmission electron microscopy. To complete the analysis, the microhardness profile was also performed for both PO and AR samples. The PO samples showed higher microhardness and greater amount of induced martensite and work hardening in the surface in comparison with AR samples. Independently of applied load and initial surface condition, two different stages on the friction behavior can be identified in dry tests. On the contrary, a stable behavior is observed in lubricated tests. Moreover, whereas in lubricated tests wear behavior is independent of surface finishing conditions and load, it shows a pronounced influence with load in dry tests.

Texture strengthening and anisotropic hardening of mill annealed Ti-6Al-4V alloy under equi-biaxial tension

This work investigates the influence of equi-biaxial stress state on the deformation response of Ti-6Al-4V alloy in mill-annealed condition using a newly designed cruciform specimen geometry. The proposed geometry was validated using a non-contact strain measurement technique to obtain maximum plastic strain in the gage section. It is observed that the elasto-plastic response of Ti-6Al-4V alloy was profoundly influenced by the stress state and the loading orientation with respect to the rolling direction. The strengthening effect and the in-plane plastic anisotropic evolution observed under equi-biaxial stress state was ascribed to the presence of strong crystallographic texture in the as-received condition. The dominant deformation mechanisms operating under equi-biaxial stress state were deduced from the texture evolution studies.

Design and Optimization of the Local Laser Treatment to Improve the Formability of Age Hardenable Aluminium Alloys.

The research of innovative methodologies to improve the Aluminium alloys formability at room temperature still remains an open question: the local modification of the material properties via short-term heat treatments followed by the stamping at room temperature is reported to be an effective alternative to the forming in warm conditions. In the present work, such a methodology has been applied to the deep drawing of an age-hardenable Aluminium alloy (AA6082-T6) using an experimental/numerical approach. A preliminary extensive material characterization was aimed at investigating the material behaviour: (i) in the as-received condition (peak hardening), (ii) in the supersaturated condition (obtained by physical simulation) and (iii) after being locally solutioned via laser heating. A Finite Element based approach (Abaqus CAE, v. 6.17) was then used to design the laser treatment of the blanks to be subsequently deep drawn at room temperature: a 2D axisymmetric model of the deep drawing process was coupled with the optimization platform modeFRONTIER in order to define the radial extent of the laser heat treated area able to maximize the Limit Drawing Ratio. The experimental tests were finally conducted for validation purposes and revealed the effectiveness of the adopted approach which allowed to improve the drawability of more than 20% with respect to the as received condition (T6).

The effect of Equal Channel Angular Pressing on the stress corrosion cracking susceptibility of AZ31 alloy in simulated body fluid

Despite the great potential of Mg and its alloys as material for biodegradable implants, their low resistance to the simultaneous action of corrosion and mechanical stresses in the human body have hampered their use. Stress Corrosion Cracking has been reported as one of the most critical failure modes to overcome to allow such materials to be clinically applied. Thus, in this paper we investigate the effect of Equal Channel Angular Pressing (ECAP) on the Stress Corrosion Cracking (SCC) susceptibility of the AZ31 Mg alloy. To do so, AZ31 alloy has been subjected to 1, 2 and 4 passes of ECAP, and the samples so obtained have then been tested by means Slow Strain Rate Tests (SSRTs) in Simulated Body Fluid (SBF) at 37 °C. Samples subjected to one pass of ECAP are shown to be less susceptible to SCC compared to the material in the as-received condition, while further ECAP processing (2 and 4 passes) are found to worsen the SCC susceptibility. To understand the different SCC susceptibilities shown by the differently ECAPed samples, microstructural analyses, potentiodynamic polarization curves, hydrogen evolution experiments and Scanning Electron Microscopy (SEM) analyses of the fracture surfaces were carried out. The improved corrosion resistance of the samples subjected to 1 pass of ECAP compared to the samples in the as received condition (due to a finer grain size) and to the samples subjected to 2 and 4 passes (due to a more favourable texture evolution) represents the reason of their reduced SCC susceptibility.

The Effect of Service on Microstructure and Mechanical Properties of HR3C Heat-Resistant Austenitic Stainless Steel.

The physical metallurgical tests were performed on the test samples made of HR3C steel, taken from a section of a pipeline in the as-received condition and after approximately 26,000 h of service at 550 °C. In the as-received condition, the test material had austenitic microstructure with numerous large primary Z-phase precipitates inside the grains. The service of the test steel mainly contributed to the precipitation processes inside the grains and at the grain boundaries. After service, the following precipitates were identified in the microstructure of the test steel: Z-phase (NbCrN) and M23C6 carbides. The Z-phase precipitates were observed inside the grains, whereas M23C6 carbides - at the boundaries where they formed the so-called continuous grid. The service of the test steel contributed to the growth of the strength properties, determined both at room and elevated temperature (550, 600 °C), compared to the as-received condition. Moreover, the creep properties of HR3C steel after service were higher than those of the material in the as-received condition. The increase in the strength properties and creep resistance was connected with the growth of strengthening of the test steel by the precipitation of Z-phase and M23C6 carbides.

A potential insight into the serration behaviour of Σ3n (n≤3) boundaries in Alloy 617

The serration behavior of Σ3n (n ≤ 3) boundaries in Alloy 617 is investigated through electron back scattered diffraction analysis and molecular dynamics (MD) simulation. Furthermore, the implication of grain boundary serrations on the corrosion response in alloy 617 was also evaluated. While Ʃ3 boundaries are never serrated, both Ʃ9 and Ʃ27 boundaries showed mixed serration behavior. Five parameter stereological analysis has revealed that the Ʃ9 and Ʃ27 boundaries lie on both low and high index planes. This observation justifies the mixed serration behavior of Ʃ9 and Ʃ27 considering the fact that boundaries lying on high index planes possess higher surface energy as substantiated through molecular dynamics simulation. Finally, a ‘misorientation-deviation’ based approach is proposed which could mostly identify those Ʃ9 and Ʃ27 boundaries which are likely to be serrated. The corrosion studies revealed that the serrated specimen is highly resistant to corrosion against the as-received condition.

Influence of strain rate and strain at temperature on TRIP effect in a metastable austenitic stainless steel

Metastable TRIP (TRansformation-Induced Plasticity) steel strips with a microstructure comprising ferrite, retained austenite and martensite were subjected to tensile tests at different strain rates of 10−5s−1, 10−4s−1, 10−3s−1 and temperatures 27 °C, 50 °C and 100 °C. The TRIP steel specimens exhibited very high tensile strengths (up to ~1700 MPa) in tests carried out at room temperature, which is attributed to the TRIP effect. Thermal stability of the phases present in the TRIP steel in the as-received condition was assessed by in-situ high temperature XRD and DSC (Differential Scanning Calorimetry) analysis to determine the retained austenite decomposition temperature. Microstructural analysis by XRD, optical microscopy and electron microscopy was used before and after the tensile tests to identify the features present at micro- and nano-scales, which are responsible for the observed mechanical properties. Macrographs taken from the surface of the specimens after the tensile tests showed the presence of Lüders bands and their occurrence was concurrent with the TRIP effect. The effect of strain rate and temperature on the TRIP effect and the associated mechanical response are discussed in detail.

Insitu investigation of tensile deformation behaviour of cold-rolled interstitial-free high-strength steel in scanning electron microscope

The progress of tensile deformation of cold rolled interstitial-free high-strength (IFHS) steel in the as-received and 10 pct tensile pre-strained conditions has been studied through testing of miniature sized specimens in scanning electron microscope. Strength and ductility of the steel obtained through insitu tests have been compared with the macro tensile test results. The insitu test results show that the yield strength and tensile strength of miniature sized specimens are less as compared to that of macro tensile test results. But, uniform strain in case of insitu tests is higher than that obtained in case of macro tensile specimens. The insitu tests reveal that intergranular cracking of surface grains and formation of both intergranular and transgranular voids precede the final ductile fracture. The areal density of voids is found to increase with increase of Von Mises equivalent plastic strain. Under pre-strained condition void nucleation strain of the steel is found to be lower as compared to the as-received condition.

Investigations on strain distribution, stress-based fracture limit and corrosion behaviour of titanium Grade 2 sheets during single point incremental forming

Purpose The purpose of this paper is to investigate the strain distribution, stress-based fracture limit and corrosion behaviour of titanium Grade 2 sheets during single point incremental forming (SPIF) process, with various computerized numerical control (CNC) spindle rotational speeds and step depths. The development of corrosion pits in 3.5 (%) NaCl solution has also been studied during the SPIF process. Design/methodology/approach A potentiodynamic polarization (PDP) study was performed to investigate the corrosion behaviour of titanium Grade 2 deformed samples, with various spindle rotational speeds in 3.5 (%) NaCl solution. The scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis was carried out to study the fracture behaviour, dislocation densities and corrosion morphology of deformed samples. Findings The titanium Grade 2 sheets exhibited better strain distribution, fracture limit and corrosion resistance by increasing the CNC spindle rotational speeds, tool diameters and vertical step depths (VSD). It was recorded that varying the spindle speed affected plastic deformation which in turn affected corrosion rate. Research limitations/implications In this study, poor corrosion rate was observed for the as-received condition, and better corrosion rate was achieved at maximum speed of 600 rpm and 0.6 mm of VSD in the deformed sheet. This indicates that corrosion rate improved with increase in the plastic deformation. The EDS analysis report of corroded surface revealed the composition to be mainly of titanium and oxides. Practical implications This study discusses the strain distribution, stress-based fracture limit and corrosion behaviour by using titanium Grade 2 sheets during SPIF process. Social implications This study is useful in the field of automobile and industrial applications. Originality/value With an increase in the spindle rotational speeds and VSD, the titanium Grade 2 sheets showed better strain distribution, fracture limit and corrosion behaviour; the same is evidenced in fracture limit curve and PDP curves.

Development of a brazing procedure to join W-2Y2O3 and W-1TiC PIM materials to Eurofer

The present work proposes a brazing technique to address both the mechanical and metallurgical requirements of joining two different tungsten powder injection moulding materials (W-2Y2O3 and W-1TiC) with Eurofer steel. The joining procedure uses pure copper as a filler material and the brazing parameters are 1135 °C for 10 min in a high vacuum furnace. Metallurgical evaluation indicates the achievement, in both cases, of 100% metallic continuity at the interface. The brazing temperature is high enough to activate diffusion phenomena at the interface, giving rise to strong adhesion properties. The mechanical properties are evaluated by shear strength tests with values of 163 ± 55 and 162 ± 6 MPa for W-2Y2O3/Eurofer and W-1TiC/Eurofer, respectively. These values are considerably higher than those obtained in previous works using other interlayer materials. The microhardness of these W-base materials is similar to that in the as-received condition, indicating that it was not affected by the brazing process.

Effects of hot forging on the structural condition in HS 6-5-2 high-speed steel

Microstructure analysis was performed on rolled bars of high-speed steel after two and three forging cycles, each cycle comprising one upsetting and one drawing out operation. High-speed steels belong to difficult-to-form materials with a narrow forging temperature interval. Forging above the maximum forging temperature may lead to grain coarsening. Below the minimum forging temperature, deformation resistance of the material increases, and the workpiece may fail. Using numerical modelling, special forging dies were designed and effective strain distribution was calculated for an axial cross-section plane in specimens after two and three forging cycles. The purpose of the analysis was to identify the relationship between the amount of effective strain and the shape and size of austenite grain and the volume fraction and density of carbides after forging. The size of prior austenite grains was measured using the linear intercept method which is based on the Snyder-Graff method. Grain shapes were characterized in terms of circularity, which is the difference between the shape in question and a circle. With increasing amount of strain, the grains in the material became finer, as undissolved carbides impeded grain growth. In as-received rolled condition, the austenite grain size was G9. After three forging cycles, it was smaller, G11 (the higher the number, the smaller the grains). Circularity characterizes the complexity of a grain shape. Micrographs of carbide particles were taken using a scanning electron microscope and examined with NIS Elements image analysis software. The majority of carbides were sized between 0.2 and 2 μm. The carbides which are less than 1 μm in size do not shrink in response to increasing strain and their quantity does not change appreciably. Carbides with a size of 1-2 μm show a different behaviour. In the central region of specimens, where strain is the largest, their amounts are much larger than in less-worked regions.

Reproducibility of the Corrosion Resistance of UNS S32205 and UNS S32304 Stainless Steel Reinforcing Bars

One strategy to address the 75-year service life requirement of a number of highway bridge design codes is the use of more corrosion-resistant reinforcement. Over the last few decades, many stainless steel grades have become available for reinforcing concrete. Of these, two duplex alloys, UNS S32205 and UNS S32304, have become the preferred choices for major highway structures in North America. The purpose of the present study was to investigate the consistency, or variability, of the corrosion performance of bars of these grades from different steel manufacturers. Metallography, chemical analysis, corrosion resistance, and corrosion product evaluation were used to evaluate the bars. It was found that micropits exist to varying degree in the as-received conditions of these bars and that was the most dominant factor in determining the corrosion performance of the bars.

Electron beam welding of oxide dispersion strengthened 9 Cr martensitic steel-an experimental and theoretical perspective

Abstract Advanced nuclear energy systems present significant improvements in economics, safety, reliability and sustainability over currently operating reactor technologies. Proper choices of cladding and structural material with a. high neutron damage resistance b. good mechanical properties at high operating temperatures and c. low activation properties are essential for the safe and reliable operation of the system. The 9-12% Cr transformable steels with lower carbon (∼0.1%) contents and addition of Mo, W, V, Nb present better high temperature strength than austenitic steels. The use of 9%Cr steel is considered as an optimum solution taking into consideration the present day requirements like environment, efficiency, elasticity, experience and economy that dominate considerations of modern power station design, layout, fabrication and operation. The pursuit of improved efficiency/power plant performance resulted in the design of system operating at higher temperature and pressure, which requires materials with appropriate high-temperature mechanical properties and metallurgical stability at operating temperatures. Oxide Dispersion Strengthened (ODS) 9% Cr steels have the potential to advance the high temperature performance of associated components in advanced nuclear energy systems with marginal oxidation resistance. The research focuses on Electron beam welding (EBW) of Hot Isostatically Pressed (HIP) ODS 9 Cr martensitic steel in as-received condition to arrive at the optimized weld process parameters. The weldments were characterized using Optical Microscopy for depth of penetration and width of weldments. The experimental results were theoretically verified using Minitab software

Influence of Upset Pressure on Microstructure and Mechanical Properties of Friction-Welded AISI 4140 Low Alloy Steel Pipes

In the present study, low alloy steel AISI 4140 pipe in reheated, quenched and tempered (RQT) condition was friction-welded using 6.4 MPa upset pressure followed by post-weld heat treatment as per the manufacturing practice prevailing in the drill pipe industry and compared the same with friction welds made at different upset pressures in the RQT condition and in the as-received condition to evaluate bond quality. The weld region consisted of a mixture of tempered martensite and ferrite in case of RQT condition and mixture of lath martensite/upper bainite and ferrite in the as-received condition. As the upset pressure was increased, the martensite lath size decreased in both as-received and RQT conditions. In general, as the upset pressure was increased, the average microhardness increased. The average microhardness of the material adjacent to partially deformed zone showed lower hardness due to tempering effect because of weld heat. The upset pressure 6.4 MPa showed better notch tensile strength ratio confirming better ductility of the weld zone. The impact strength decreased as the upset pressure increased in both as-received and RQT conditions. But as-received condition showed significantly lower impact strength due to higher carbide content at the weld interface.