scholarly journals On the Impact of the Intermetallic Fe2Nb Laves Phase on the Mechanical Properties of Fe-6 Al-1.25 Nb-X W/ Mo Fully Ferritic Light-Weight Steels

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1693
Author(s):  
Robin Emmrich ◽  
Ulrich Krupp
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Xrd Analysis ◽  
Tensile Tests ◽  
Laves Phase ◽  
Particle Analysis ◽  
Strength Increase ◽  
Niobium Content ◽  
The Impact

The present study aims at the development of precipitation hardening fully ferritic steels with increased aluminum and niobium content for application at elevated temperatures. The first and second material batch were alloyed with tungsten or molybdenum, respectively. To analyze the influence of these elements on the thermally induced precipitation of the intermetallic Fe2Nb Laves phase and thus on the mechanical properties, aging treatments with varying temperature and holding time are performed followed by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) including elemental contrast based particle analysis as well as hardness measurements and tensile tests at room temperature and at 500 °C. The incorporation of molybdenum into the Laves phase sets in at an earlier stage of aging than the incorporation of tungsten, which leads to faster growth and coarsening of the Laves phase in the molybdenum-alloyed steel. Nevertheless, both concepts show a fast and massive increase in hardness (280 HV10) due to precipitation of Laves phase during aging at 650 °C. After 4 h aging, the yield strength increase at room temperature is 100 MPa, which stays stable at operation temperatures up to 500 °C.

A research on the effect of retrogression and re-aging heat treatment on hot tensile properties of AA7075 aluminum alloys

2021 ◽  
pp. 1-23
Author(s):  
Talha Sunar ◽  
Dursun Ozyurek
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Ductile Fracture ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Xrd Analysis ◽  
Tensile Tests ◽  
Heat Treatments ◽  
Tensile Behaviour ◽  
Heat Treated

Abstract Aluminium alloys are preferred in most industries due to the functional properties they provide. It is known that alloys that can be processed with heat treatments shows better mechanical properties. 7xxx series alloys can be processed vi heat treatments and are often used in environmental conditions such as extreme temperatures and corrosive environments. Corrosive sensitivities such as stress corrosion cracking (SCC) can be observed with the effect of working conditions. It is known that retrogression and re-aging (RRA) heat treatment provide corrosion resistance and decrease the SCC velocity. The purpose of this study is to examine the tensile behaviour of annealed and retrogression-re-aging (RRA) heat treated AA7075 alloys at elevated temperatures. The mechanical properties of the alloys were investigated by conducting tensile tests at room temperature (RT), 100, 200, and 300°C. Hardness tests were performed at room temperature on the samples which were taken from tensile test specimens after tensile tests. The potential effects of test temperature on mechanical and microstructural properties were examined. The annealed and RRA heat treated alloys were characterized by scanning electron microscope (SEM), and X-ray diffraction (XRD) analysis. As a result, an increase in strength and hardness of the RRA treated AA7075 alloys was observed. Ductility of the RRA alloy was lower compared to the annealed AA7075 alloy. Fracture surface examinations showed that there was a semi-ductile fracture below 200°C and ductile fracture at temperatures of 200 and 300°C. Ductility was observed to increase with increasing temperature.

Effect of Ca and Sr Content on Elevated Temperatures Mechanical Properties of a Cast AZ91 Magnesium Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 141-144
Author(s):  
Ippei Takeuchi ◽  
Kinji Hirai ◽  
Yorinobu Takigawa ◽  
Tokuteru Uesugi ◽  
Kenji Higashi
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Creep Resistance ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Az91 Magnesium Alloy ◽  
Additional Amount ◽  
Az91 Magnesium ◽  
Second Phases

The effect of Ca and Sr content on the microstructure and mechanical properties of a cast AZ91 magnesium alloy is investigated. Ca and Sr additions in AZ91 magnesium alloy are expected high creep resistance. The microstructure of the alloy exhibits the dendritic α-matrix and the second-phases forming networks on the grain boundary. Tensile tests at elevated temperatures between 448 and 523K reveal that the creep resistance was improved with increasing the additional amount of Ca, especially more than 1.0wt%. From the perspective of grain refinement effect, it is expected that the additions of Ca and Sr to AZ91 magnesium alloy not only improve creep resistance but also improve mechanical properties at room temperature.

scholarly journals The Effects of Various Conditions of Short-Term Rejuvenation Heat Treatment on Room-Temperature Mechanical Properties of Thermally Aged P92 Boiler Steel

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6076
Author(s):  
Ladislav Falat ◽  
Lucia Čiripová ◽  
Viera Homolová ◽  
Miroslav Džupon ◽  
Róbert Džunda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Toughness ◽  
Room Temperature ◽  
Laves Phase ◽  
Short Term ◽  
Boiler Steel ◽  
P92 Steel ◽  
The Impact

In this work, the effects of various conditions of short-term rejuvenation heat treatment on room-temperature mechanical properties of long-term aged P92 boiler steel were investigated. Normalized and tempered P92 steel pipe was thermally exposed at 600 °C for time durations up to 5000 h in order to simulate high-temperature material degradation, as also occurring in service conditions. Thus, thermally embrittled material states of P92 steel were prepared, showing tempered martensitic microstructures with coarsened secondary phase precipitates of Cr23C6-based carbides and Fe2W-based Laves phase. Compared with the initial normalized and tempered material condition, thermally aged materials exhibited a slight decrease in strength properties (i.e., yield stress and ultimate tensile strength) and deformation properties (i.e., total elongation and reduction of area). The hardness values were almost unaffected, whereas the impact toughness values showed a steep decrease after long-term ageing. An idea for designing the rejuvenation heat treatments for restoration of impact toughness was based on tuning the material properties by short-term annealing effects at various selected temperatures somewhat above the long-term ageing temperature of P92 material. Specifically, the proposed heat treatments were performed within the temperature range between 680 °C and 740 °C, employing variable heating up and cooling down conditions. It was revealed that short-term annealing at 740 °C for 1 h with subsequent rapid cooling into water represents the most efficient rejuvenation heat treatment procedure of thermally aged P92 steel for full restoration of impact toughness up to original values of normalized and tempered material state. Microstructural observations clearly indicated partial dissolution of the Laves phase precipitates to be the crucial phenomenon that played a key role in restoring the impact toughness.

Springback Behavior of an Invar Sheet and Its Perforated Form

2006 ◽  
Vol 505-507 ◽  
pp. 781-786
Author(s):  
Yi Che Lee ◽  
Fuh Kuo Chen
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Test Results ◽  
Bending Tests ◽  
Predicted Values ◽  
Springback Behavior ◽  
Good Agreement

The springback behavior of an invar sheet and its perforated form were examined in the present study. The mechanical properties for invar sheet and perforated invar-sheet at elevated temperatures were first obtained from tensile tests. The test results suggest that both invar sheet and perforated invar-sheet have favorable formability at temperature higher than 200oC. An analytical model was also established to predict the springback of the invar sheet and its perforated form under bending conditions at various elevated temperatures. In order to verify the predicted results, the V-bending tests were conducted for the invar sheet at various temperatures ranging from room temperature to 300. The experimental data indicate that the springback decreases with the rise in temperature for both invar sheet and perforated invar-sheet. The good agreement between the experimental data and the predicted values confirms the validity of the proposed theoretical model as well.

The Mechanical Properties of Fe-36.5Al and its Cr or ti Containing Alloys at Elevated Temperature

1994 ◽  
Vol 364 ◽  
Author(s):  
Dingqiang Li ◽  
Yi Liu ◽  
Aidang Shan ◽  
Dongliang Lin
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Ternary Alloys ◽  
Transgranular Cleavage ◽  
Feal Alloy ◽  
Fracture Surfaces ◽  
Increasing Temperature

AbstractThe mechanical properties of B2 structural FeAl alloys, prepared by hot rolling, at elevated temperatures have been measured by tensile tests. The alloys of Fe-36.5at.%A1, Fe-36.5at.%A1-5at.%Cr and Fe-36.5at.%Al-2at.%Ti were taken for tensile tests at a temperature range from room temperature to 1000°C. The fracture surfaces of these alloys were observed by SEM. The results showed that elongations of these alloys increased with increasing temperature when the testing temperatures were above 600°C. All the maximum elongations of these alloys appeared at 1000°C and those of Fe-36.5A1, Fe-36.5Al-5Cr, and Fe-36.5Al-2Ti alloys were 120%, 183% and 208% respectively. Fracture surfaces showed that failure of these alloys was by a combination of intergranular fracture and transgranular cleavage below 700°C. but showed a ductile fracture above 700°C. The ductility and strength of ternary alloys were higher than that of binary FeAl alloy at elevated temperatures, especially at high temperature. The <111> dislocations and helices have been observed in Fe-36.5A1 alloy by TEM. The large elongation of FeAl alloy at high temperature resulted from <111> dislocations slipping and <111> helices climbing.

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

scholarly journals Strength Enhancement of Superduplex Stainless Steel Using Thermomechanical Processing

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1094
Author(s):  
M. A. Lakhdari ◽  
F. Krajcarz ◽  
J. D. Mithieux ◽  
H. P. Van Landeghem ◽  
M. Veron
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Thermomechanical Processing ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strength Enhancement ◽  
Industrial Material ◽  
Superduplex Stainless Steel ◽  
The Impact ◽  
Strength Improvement

The impact of microstructure evolution on mechanical properties in superduplex stainless steel UNS S32750 (EN 1.4410) was investigated. To this end, different thermomechanical treatments were carried out in order to obtain clearly distinct duplex microstructures. Optical microscopy and scanning electron microscopy, together with texture measurements, were used to characterize the morphology and the preferred orientations of ferrite and austenite in all microstructures. Additionally, the mechanical properties were assessed by tensile tests with digital image correlation. Phase morphology was not found to significantly affect the mechanical properties and neither were phase volume fractions within 13% of the 50/50 ratio. Austenite texture was the same combined Goss/Brass texture regardless of thermomechanical processing, while ferrite texture was mainly described by α-fiber orientations. Ferrite texture and average phase spacing were found to have a notable effect on mechanical properties. One of the original microstructures of superduplex stainless steel obtained here shows a strength improvement by the order of 120 MPa over the industrial material.

scholarly journals Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire

2021 ◽  
Vol 13 (10) ◽  
pp. 5494
Author(s):  
Lucie Kucíková ◽  
Michal Šejnoha ◽  
Tomáš Janda ◽  
Jan Sýkora ◽  
Pavel Padevět ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Cross Section ◽  
Negative Impact ◽  
Tensile Tests ◽  
Thermal Recovery ◽  
Bending Test ◽  
Small Scale ◽  
Spruce Wood ◽  
The Impact

Heating wood to high temperature changes either temporarily or permanently its physical properties. This issue is addressed in the present contribution by examining the effect of high temperature on residual mechanical properties of spruce wood, grounding on the results of full-scale fire tests performed on GLT beams. Given these tests, a computational model was developed to provide through-thickness temperature profiles allowing for the estimation of a charring depth on the one hand and on the other hand assigning a particular temperature to each specimen used subsequently in small-scale tensile tests. The measured Young’s moduli and tensile strengths were accompanied by the results from three-point bending test carried out on two groups of beams exposed to fire of a variable duration and differing in the width of the cross-section, b=100 mm (Group 1) and b=160 mm (Group 2). As expected, increasing the fire duration and reducing the initial beam cross-section reduces the residual bending strength. A negative impact of high temperature on residual strength has also been observed from simple tensile tests, although limited to a very narrow layer adjacent to the charring front not even exceeding a typically adopted value of the zero-strength layer d0=7 mm. On the contrary, the impact on stiffness is relatively mild supporting the thermal recovery property of wood.

scholarly journals Mechanical, Thermal and Rheological Properties of Polyethylene-Based Composites Filled with Micrometric Aluminum Powder

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1242
Author(s):  
Olga Mysiukiewicz ◽  
Paulina Kosmela ◽  
Mateusz Barczewski ◽  
Aleksander Hejna
Keyword(s):  
Mechanical Properties ◽  
Melt Flow Index ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Flow Index ◽  
Scanning Calorimetry ◽  
Metal Composites ◽  
Pre Treatment ◽  
The Impact ◽  
Properties Of Composites

Investigations related to polymer/metal composites are often limited to the analysis of the electrical and thermal conductivity of the materials. The presented study aims to analyze the impact of aluminum (Al) filler content (from 1 to 20 wt%) on the rarely investigated properties of composites based on the high-density polyethylene (HDPE) matrix. The crystalline structure, rheological (melt flow index and oscillatory rheometry), thermal (differential scanning calorimetry), as well as static (tensile tests, hardness, rebound resilience) and dynamic (dynamical mechanical analysis) mechanical properties of composites were investigated. The incorporation of 1 and 2 wt% of aluminum filler resulted in small enhancements of mechanical properties, while loadings of 5 and 10 wt% provided materials with a similar performance to neat HDPE. Such results were supported by the lack of disturbances in the rheological behavior of composites. The presented results indicate that a significant content of aluminum filler may be introduced into the HDPE matrix without additional pre-treatment and does not cause the deterioration of composites’ performance, which should be considered beneficial when engineering PE/metal composites.

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