The Changes in Mechanical Properties of Austenitic Creep Resistant Steels SUPER 304H and HR3C Caused by Medium-Term Isothermal Ageing

2016 ◽  
Vol 258 ◽  
pp. 639-642 ◽  
Author(s):  
Jakub Horváth ◽  
Jiří Janovec ◽  
Michal Junek
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Power Plants ◽  
Secondary Phase ◽  
Thermal Exposure ◽  
Austenitic Steels ◽  
Secondary Phases ◽  
Initial State ◽  
The Impact

The paper presents the results of the analysis of secondary phases formed during thermal exposure in creep resistant austenitic steels of SUPER 304H and HR3C types. These steels were worldwide used for construction of the superheaters (the heat exchangers) of supercritical and ultra-supercritical (USC) coal-fired power plants. In order to accelerate precipitation processes, the steels were isothermally aged at 675 °C for 20 000 h. The investigations of the precipitates were primarily focused on the occurrence of brittle phases. Changes in mechanical properties caused by occurrence of secondary phases were documented by tensile testing and measurement of the impact strength. For comparison reasons, the impact tests of the initial state of the steels were also performed. The results showed that long-term ageing had led to the significant decrease of the impact strength. Correlation between precipitation of secondary phase and measured values of mechanical properties is shown. The influence of brittle phases on long-term durability of the degraded steel regarding its insufficient impact strength has been discussed.

The Influence of the Long-Term Storage of Hardwood on the Selected Physical and Mechanical Properties in View of Pulping

2016 ◽  
Vol 688 ◽  
pp. 10-16
Author(s):  
Blažej Seman ◽  
Anton Geffert ◽  
Jarmila Geffertova
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Continuous Production ◽  
Beech Wood ◽  
Physical And Mechanical Properties ◽  
Long Term Storage ◽  
The Impact ◽  
Term Storage ◽  
Strength In Bending

Wood is loosely stored to ensure continuous production inside paper mills where it is exposed to the effect of external factors. The impact of storage leads to some changes of mechanical and physical properties of wood, but these changes are not the same in all specimens. In this paper, it has been observed that the long term storage of wood influences the impact strength in bending and the permeability of wood for fluids. During the storage, there was a decrease of impact strength in bending of poplar heartwood by 28.3% and oak by 22.1% and mature beech wood by 37.3%. Also, there was decreased a permeability of wood, poplar sapwood 18.3 % and heartwood of 53.9%; oak sapwood by 20.0% and heartwood by 20.3%; beech sapwood 45.8% and mature wood by 48.2%. By decrease of the observed properties of the stored wood, a deterioration a quality of produced pulp can be expected (a higher Kappa number, amount reject and decrease the mechanical properties of pulp).

Effect of Static Aging on Mechanical Properties of an 18Cr-8Ni-W-Nb-V-N Stainless Steel

2012 ◽  
Vol 706-709 ◽  
pp. 2211-2216
Author(s):  
Ilya Nikulin ◽  
Rustam Kaibyshev
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Impact Toughness ◽  
Early Stage ◽  
Secondary Phase ◽  
Fracture Mechanisms ◽  
Aged Condition ◽  
The Impact

The interrelations between microstructure, precipitation and mechanical properties of the 18Cr-8Ni-W-Nb-V-N austenitic stainless steel were examined under long-term aging at 650°C. It was shown that aging leads to decreasing strength characteristics with increasing aging time despite the fact that hardness tends to increase. In none-aged condition the present steel exhibits superior impact toughness of about 255 J/cm-2. This values decreases gradually at the early stage of the aging. After 1000 hours exposure the impact toughness is 195 J/cm-2 and decreases sharply to 135 J/cm-2 at 3000 hours. However, an evidence for ductile fracture was found even after long-term aging. Degradation in impact toughness and mechanical properties with aging is discussed in relation to microstructure evolution, precipitations of the secondary phase and fracture mechanisms.

scholarly journals Impact strength of denture base and reline acrylic resins subjected to long-term water immersion

2011 ◽  
Vol 22 (1) ◽  
pp. 56-61 ◽  
Author(s):  
Amanda Fucci Wady ◽  
Ana Lucia Machado ◽  
Carlos Eduardo Vergani ◽  
Ana Cláudia Pavarina ◽  
Eunice Teresinha Giampaolo
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Water Immersion ◽  
Water Storage ◽  
Charpy Impact ◽  
Denture Base ◽  
Effect Of Water ◽  
Acrylic Resins ◽  
The Impact

Water may influence the mechanical properties of the acrylic resins. Thus, the effect of water storage on the impact strength (IS) of one denture base (Lucitone 550 - L) and four reline resins (Tokuyama Rebase II - T; UfiGel Hard - U; Kooliner - K; New Truliner - NT) was evaluated. Bars of L were made (60 x 6 x 2 mm) and relined (2 mm) with T, U, K, NT and L. Intact specimens of each material (60 x 6 x 4 mm) were also fabricated for comparative purposes. Specimens were submitted to Charpy impact tests without water storage (control) and after immersion in water for 7, 90 and 180 days. Data (kJ/m²) analyzed by two-way ANOVA and Tukey's test (p=0.05) revealed that after 90 days, U exhibited an increase in the IS (0.93) compared to 7 days (0.58). K (1.48) and L/K (7.21) exhibited a decrease at the 7-day period (1.01 and 3.23, respectively). NT (0.60) showed an increase in the IS after 180 days (1.52), whereas L/NT (7.70) showed a decrease (3.17). Water immersion improved the IS of U and NT, and decreased the IS of K, L/K, and L/NT. Water may affect differently the IS of acrylic resins and, consequently, the resistance to fracture of relined denture bases.

scholarly journals Effect of Different Variants of Heat Treatment on Mechanical Properties of the AlSi17CuNiMg Alloy

2016 ◽  
Vol 16 (2) ◽  
pp. 41-44 ◽  
Author(s):  
A. Jarco ◽  
J. Pezda
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Impact Strength ◽  
High Hardness ◽  
Dispersion Hardening ◽  
Initial State ◽  
Plastic Properties ◽  
Fourfold Increase ◽  
The Impact

Abstract Dispersion hardening, as the main heat treatment of silumins having additions of copper and magnesium, results in considerable increase of tensile strength and hardness, with simultaneous decrease of ductility of the alloy. In the paper is presented an attempt of introduction of heat treatment operation consisting in homogenizing treatment prior operation of the dispersion hardening, to minimize negative effects of the T6 heat treatment on plastic properties of hypereutectoidal AlSi17CuNiMg alloy. Tests of the mechanical properties were performed on a test pieces poured in standardized metal moulds. Parameters of different variants of the heat treatment, i.e. temperature and time of soaking for individual operations were selected basing on the ATD (Thermal Derivation Analysis) diagram and analysis of literature. The homogenizing treatment significantly improves ductility of the alloy, resulting in a threefold increase of the elongation and more than fourfold increase of the impact strength in comparison with initial state of the alloy. Moreover, the hardness and the tensile strength (Rm) of the alloy decrease considerably. On the other hand, combination of the homogenizing and dispersion hardening enables increase of elongation with about 40%, and increase of the impact strength with about 25%, comparing with these values after the T6 treatment, maintaining high hardness and slight increase of the tensile strength, comparing with the alloy after the dispersion hardening.

Stability of Microstructure and Mechanical Properties of GH984G Alloy during Long-Term Thermal Exposure

2013 ◽  
Vol 747-748 ◽  
pp. 647-653 ◽  
Author(s):  
Ting Ting Wang ◽  
Chang Shuai Wang ◽  
Jian Ting Guo ◽  
Lan Zhang Zhou
Keyword(s):  
Mechanical Properties ◽  
Grain Boundary ◽  
Power Plants ◽  
Low Cost ◽  
Thermal Exposure ◽  
Tensile Tests ◽  
Experimental Results ◽  
Σ Phase ◽  
Microstructure And Mechanical Properties

A low cost Ni-Fe-based wrought superalloy for 700 advance ultra-supercritical coal-fired power plants was developed. The stability of microstructure and mechanical properties of this alloy during long-term thermal exposure was investigated by SEM,TEM and tensile tests. The experimental results showed that the major precipitates in the alloy were spherical γ, MC and discrete M23C6 distributing along grain boundary after the long-term exposure at 700 and 750 and no harmful phases, such as σ phase and η phase, were found. However, after exposure at 800 up to 3000 h, small amount of lath-like η phase precipitated at grain boundary by consuming the surrounding γ. The η phase exhibited a fixed orientation relationship with the γ matrix. During thermal exposure γ coarsened with increasing the exposure time and exposure temperature. In addition, all major phases and their stability temperature ranges were calculated by JMatPro and these results were confirmed by the experimental results. The 700 tensile tests revealed that the alloy after exposure at 700 and 750 for 3000 h exhibited excellent ductility and strength. Therefore, the GH984G alloy possessed excellent stability of microstructure and mechanical properties between 700 and 750 up to 3000 h, and it is a promising material for 700 advance ultra-supercritical coal-fired power plants.

A novel recycled polyethylene terephthalate/polyamide 11 (rPET/PA11) thermoplastic blend

2021 ◽  
pp. 147776062110010
Author(s):  
Zahid Iqbal Khan ◽  
Zurina Binti Mohamad ◽  
Abdul Razak Bin Rahmat ◽  
Unsia Habib ◽  
Nur Amira Sahirah Binti Abdullah
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Flexural Strength ◽  
Polyethylene Terephthalate ◽  
Practical Implication ◽  
Polyamide 11 ◽  
Recycled Polyethylene ◽  
Twin Screw ◽  
Electron Microscopy Analysis ◽  
The Impact

This work explores a novel blend of recycled polyethylene terephthalate/polyamide 11 (rPET/PA11). The blend of rPET/PA11 was introduced to enhance the mechanical properties of rPET at various ratios. The work’s main advantage was to utilize rPET in thermoplastic form for various applications. Three different ratios, i.e. 10, 20 and 30 wt.% of PA11 blend samples, were prepared using a twin-screw extruder and injection moulding machine. The mechanical properties were examined in terms of tensile, flexural and impact strength. The tensile strength of rPET was improved more than 50%, while the increase in tensile strain was observed 42.5% with the addition of 20 wt.% of PA11. The improved properties of the blend were also confirmed by the flexural strength of the blends. The flexural strength was increased from 27.9 MPa to 48 MPa with the addition of 30 wt.% PA11. The flexural strain of rPET was found to be 1.1%. However, with the addition of 10, 20 and 30 wt.% of PA11, the flexural strain was noticed as 1.7, 2.1, and 3.9% respectively. The impact strength of rPET/PA11 at 20 wt.% PA11 was upsurged from 110.53 to 147.12 J/m. Scanning electron microscopy analysis revealed a dispersed PA11 domain in a continuous rPET matrix morphology of the blends. This work practical implication would lead to utilization of rPET in automobile, packaging, and various industries.

The Effect of Aging Heat Treatment on the Microstructure and Mechanical Properties of 10Cr20Ni25Mo1.5NbN Austenitic Steel

2016 ◽  
Vol 35 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Zhiyuan Liang ◽  
Wanhua Sha ◽  
Qinxin Zhao ◽  
Chongbin Wang ◽  
Jianyong Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Austenitic Steel ◽  
Treatment Time ◽  
Aging Treatment ◽  
Secondary Phases ◽  
Aging Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
The Impact

AbstractThe effect of aging heat treatment on the microstructure and mechanical properties of 10Cr20Ni25Mo1.5NbN austenitic steel was investigated in this article. The microstructure was characterized by scanning electron microscopy, energy dispersive spectrometry and transmission electron microscopy. Results show that the microstructure of 10Cr20Ni25Mo1.5NbN austenitic is composed of austenite. This steel was strengthened by precipitates of secondary phases that were mainly M23C6 carbides and NbCrN nitrides. As aging treatment time increased, the tensile strength first rose (0–3,000 h) and then fell (3,000–5,000 h) due to the decrease of high density of dislocations. The impact absorbed energy decreased sharply, causing the sulfides to precipitate at the grain boundary. Therefore, the content of sulfur should be strictly controlled in the steelmaking process.

Mechanical Properties of Epoxy Adhesive Under Thermal Aging and Their Chemical Degradation Behavior

2021 ◽  
Vol 21 (8) ◽  
pp. 4444-4449
Author(s):  
Bongjin Chung ◽  
Shin Sungchul ◽  
Jaeho Shim ◽  
Seongwoo Ryu
Keyword(s):  
Mechanical Properties ◽  
Thermal Aging ◽  
Photoelectron Spectroscopy ◽  
Thermal Exposure ◽  
Chain Scission ◽  
Epoxy Adhesive ◽  
Chemical Degradation ◽  
Adhesive Properties ◽  
Noticeable Reduction

Epoxy adhesive was analyzed under long term thermal aging and mechanical properties and chemical degradation were observed by X-ray photoelectron spectroscopy (XPS). Long term thermal exposure of epoxy causes a noticeable reduction in adhesive properties. We developed a predictive model of temperature and time dependent aging. The temperature dependent aging behavior of epoxy adhesive shows good agreement with conventional Arrhenius equations. Using XPS analysis, we also discovered a correlation between chemical degradation and the adhesive properties. Decay of C–C bonding ratio induced chain-scission of epoxy adhesive; increase of total numbers of C–O and C═O induced oxidation of epoxy adhesive during thermal exposure.

scholarly journals ANALISIS KEKUATAN TARIK DAN IMPAK MATERIAL KOMPOSIT POLIMER DALAM APLIKASI FIBERBOAT

2021 ◽  
Vol 4 ◽  
pp. 121-126
Author(s):  
Rezza Ruzuqi ◽  
Victor Danny Waas
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Composite Materials ◽  
Impact Strength ◽  
Metal Corrosion ◽  
Phase System ◽  
Low Density ◽  
Weight Percentage ◽  
Multi Phase ◽  
The Impact

Composite material is a material that has a multi-phase system composed of reinforcing materials and matrix materials. Causes the composite materials to have advantages in various ways such as low density, high mechanical properties, performance comparable to metal, corrosion resistance, and easy to fabricate. In the marine and fisheries industry, composite materials made from fiber reinforcement, especially fiberglass, have proven to be very special and popular in boat construction because they have the advantage of being chemically inert (both applied in general and marine environments), light, strong, easy to print, and price competitiveness. Thus in this study, tensile and impact methods were used to determine the mechanical properties of fiberglass polymer composite materials. Each test is carried out on variations in the amount of fiberglass laminate CSM 300, CSM 450 and WR 600 and variations in weight percentage 99.5% -0.5%, 99% -1%, 98.5% -1, 5%, 98% -2% and 97.5%-2.5% have been used. The results showed that the greater the number of laminates, the greater the impact strength, which was 413,712 MPa, and the more the percentage of hardener, the greater the impact strength, which was 416,487 MPa. The results showed that the more laminate the tensile strength increased, which was 87.054 MPa, and the more the percentage of hardener, the lower the tensile strength, which was 73.921 MPa.

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