On the Methods for Assessing the Resistance of Steels to Brittle Fracture

2021 ◽  
pp. 59-64
Author(s):  
A.P. Korchagin ◽  
◽  
K.A. Kuznetsov ◽  
A.M. Kuznetsov ◽  
S.I. Kirillov ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Brittle Fracture ◽  
Impact Strength ◽  
Low Temperatures ◽  
Physical And Mechanical Properties ◽  
Correct Choice ◽  
Temperature Dependences ◽  
And Control ◽  
The Impact ◽  
Resistance To Brittle Fracture

The problem of assessing steels durability, their resistance to brittle fracture in the structures used in various branches of industry, remains relevant at the development of the new equipment and control of the old equipment. Standard strength calculations do not give a complete picture of the ability of steels due to their physical and mechanical properties to resist the formation and further development of defects and cracks under the action of actual stresses. The correct choice of a structural material for technical devices operating at low temperatures, knowledge of its characteristics of resistance to brittle fracture, understanding of brittle fracture mechanism at low temperatures and research in this area are of great importance. Since 1980s, JSC IrkutskNIIkhimmash systematically conducts the research works related to impact strength characteristics. These works are carried out in connection with the need for assessing the resistance to brittle fracture of metal of the equipment for storing oil products, vessels and pipelines, drill pipes and tubing, etc. As a result of many years of research, the authors accumulated significant experimental material in the form of temperature dependences of impact strength - both for the material of various types of blanks (sheets, pipes, forgings) in the state of delivery, and for the metal of technical devices elements after their operation of various duration. The main objective of the article is to assist specialists in establishing the correct choice of steel for the new or old structures in terms of their resistance to brittle fracture without conducting special studies. Specialists can select the closest steel analogue (on chemical composition, mechanical properties, and the type of product without making cuts from the structure or blanks for additional research), and set the numerical value of the impact strength, critical temperature of brittleness and the stress intensity factor for any temperature in the range from –40 to 20° С in order to use them in further calculations.

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).

scholarly journals Effect of repeated disinfections by microwave energy on the physical and mechanical properties of denture base acrylic resins

2009 ◽  
Vol 20 (2) ◽  
pp. 132-137 ◽  
Author(s):  
Rafael Leonardo Xediek Consani ◽  
Douglas Duenhas de Azevedo ◽  
Marcelo Ferraz Mesquita ◽  
Wilson Batista Mendes ◽  
Paulo César Saquy
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Flexural Strength ◽  
Physical And Mechanical Properties ◽  
Knoop Hardness ◽  
Microwave Energy ◽  
Bending Test ◽  
Denture Base ◽  
Acrylic Resins ◽  
The Impact

The present study evaluated the effect of repeated simulated microwave disinfection on physical and mechanical properties of Clássico, Onda-Cryl and QC-20 denture base acrylic resins. Aluminum patterns were included in metallic or plastic flasks with dental stone following the traditional packing method. The powder/liquid mixing ratio was established according to the manufacturer's instructions. After water-bath polymerization at 74ºC for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling and finished. Each specimen was immersed in 150 mL of distilled water and underwent 5 disinfection cycles in a microwave oven set at 650 W for 3 min. Non-disinfected and disinfected specimens were subjected to the following tets: Knoop hardness test was performed with 25 g load for 10 s, impact strength test was done using the Charpy system with 40 kpcm, and 3-point bending test (flexural strength) was performed at a crosshead speed of 0.5 mm/min until fracture. Data were analyzed statistically by ANOVA and Tukey's test (α= 0.05%). Repeated simulated microwave disinfections decreased the Knoop hardness of Clássico and Onda-Cryl resins and had no effect on the impact strength of QC-20. The flexural strength was similar for all tested resins.

scholarly journals Increasing the construction strength of petroleum pipes operating in agressive environment

2021 ◽  
pp. 70-76
Author(s):  
V.S. Chmeliova ◽  
H.I. Perchun
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Hydrogen Sulfide ◽  
Brittle Fracture ◽  
High Resistance ◽  
Structural Strength ◽  
Aggressive Environment ◽  
The Impact ◽  
Resistance To Brittle Fracture ◽  
Hydrogen Sulfide Cracking

Purpose. Questions about ways to increase the structural strength of oil country tubular goods are considered. Alloying and heat treatment of medium-alloy steels should ensure: pro-carbonization to the structure of martensite and lower bainite with a minimum carbon content (C ≤ 0.3 %), high resistance to brittle fracture and hydrogen embrittlement, the formation of uniformly distributed finely dispersed carbides and sulphides of a round shape to reduce diffusion mobile hydrogen is absorbed by steel. Propose modes of thermal treatment of casing pipes that provide the required level of mechanical and operational properties. Methodology. We used standard techniques for determining the mechanical properties in tension, dynamic bending tests and fracture studies. Results. The modes of heat treatment of casing pipes of strength category E, L are proposed, which provide the required level of mechanical and operational properties and an increase in structural strength. Originality. A systematic analysis of the influence of various factors on the structural strength of oil country tubular goods operating in an aggressive environment has been carried out. The highest degree of correlation between the value of the impact toughness and the tough component in the fracture is shown. Cooling of pipes with a nozzle sprayer of the design of the Department of Heat Treatment of Metals of NMetAU, which provides high resistance to brittle fracture by increasing the proportion of the viscous component and changing the microrelief of the cup fracture. Practical value. The proposed technology of heat treatment of oil pipes, working in an aggressive environment, provides the required level of mechanical properties and resistance to hydrogen sulfide cracking. Keywords: structural strength; oil country tubular goods; alloying; heat treatment; strength categories;temperature and deformation parameters; hydrogen sulfide cracking; brittle fracture resistance

The influence of the 3D-printing technology on the physical and mechanical properties of polyphenylene sulfone

2018 ◽  
Vol 24 (7) ◽  
pp. 1124-1130 ◽  
Author(s):  
Azamat Ladinovich Slonov ◽  
Azamat Askerovich Khashirov ◽  
Azamat Aslanovich Zhansitov ◽  
Elena Viktorovna Rzhevskaya ◽  
Svetlana Yuryevna Khashirova
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
3D Printing ◽  
Impact Strength ◽  
Orientation Angle ◽  
Physical And Mechanical Properties ◽  
Air Gap ◽  
Content Type ◽  
Fused Deposition ◽  
The Impact

Purpose This paper aims to examine the impact of three-dimensional (3D) printing technological modes (using fused deposition modelling [FDM]) on physical and mechanical properties of samples from polyphenylenesulfone. Design/methodology/approach For this study, the standard test samples were printed using the FDM method at different filament orientation angles, the gaps between them and a different width. The basic physical and mechanical properties, such as the strength, the elastic modulus and the impact strength, were studied. Findings The authors found that the basic mechanical properties strongly depend on the printing settings. In particular, the elastic modulus generally depends on the air gap between rasters, and it is practically independent of the filament orientation angle. In contrast, the impact strength depends on the orientation and the degree of adhesion between filaments: the highest values are reached at the longitudinal orientation of rasters in the sample (0°) and the minimum value of the air gap (−0.025 mm). However, in selecting the optimal mode of 3D printing, it is necessary to take into account the specific geometry of the printing products and the direction of the stress that it will experience. Originality/value The paper presents the results of the investigation of the influence of FDM printing modes on the mechanical properties of samples from polyphenylenesulfone, including impact strength. The authors studied the mechanisms of the destruction under impact loading and revealed the optimal printing settings for making samples with properties which are not inferior to the injection molded samples.

Morphological, physical and mechanical properties of nanocrystalline cellulose filled Nylon 6 foams

2016 ◽  
Vol 53 (3) ◽  
pp. 253-271 ◽  
Author(s):  
Hajar Yousefian ◽  
Denis Rodrigue
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Strength ◽  
Physical And Mechanical Properties ◽  
Mold Temperature ◽  
Nylon 6 ◽  
Nanocrystalline Cellulose ◽  
Cellulose Content ◽  
Foaming Agent ◽  
The Impact

Nanocomposite foams based on Nylon 6 and nanocrystalline cellulose were prepared via extrusion and injection molding to study the effect of nanocrystalline cellulose concentration (0 to 5%), chemical foaming agent content (0, 1%, and 2%), and mold temperature (30℃ and 80℃) on the morphological, physical, and mechanical properties of the samples. Nanocrystalline cellulose content, especially between 1 and 3 wt%, was very effective in reducing the cell size and increasing the cell density of the foam structure. Nanocrystalline cellulose addition (0–5%) was found to increase density (4% for composites and 20% for foams), tensile strength (10% for composite and 13% for foams), tensile modulus (20% for composites and 34% for foams), and flexural modulus (37% for composites and 29% for foams), but decreased the impact strength (35–40% for composites and 20–40% for foams). Foaming agent addition (1%) was able to improve the specific tensile (10%) and flexural (12%) moduli, tensile strength (14%), elongation at break (6%), and impact strength (27%). Finally, higher mold temperature decreased skin thickness and, consequently, decreased the mechanical properties, mostly tensile strength of the foam samples (1% for composites and 18% for foams).

scholarly journals Effect of Oil Paint Addition on Impact Strength of the Scleral Part of the Acrylic Ocular Prosthesis

2018 ◽  
Vol 12 (1) ◽  
pp. 946-951
Author(s):  
Firas Abd Kati
Keyword(s):  
Mechanical Properties ◽  
Titanium Dioxide ◽  
Impact Strength ◽  
Physical And Mechanical Properties ◽  
Acrylic Resin ◽  
Control Group ◽  
Ocular Prosthesis ◽  
Acrylic Resins ◽  
Oil Paints ◽  
The Impact

Background: For many dental and facial restorations, acrylic resins are the materials of choice because of their appropriate physical and mechanical properties. When making the ocular prosthesis from such materials, it is essential to add the perfect shade in order to match the colour of normal eye. This, however, might have a significant effect on the mechanical properties of acrylic resins. Objective: The purpose of this study was to assess the effect of adding the white oil paint (titanium dioxide) to clear acrylic resins on their impact strength. Methods: 20 samples were constructed from heat cured acrylic resins, and divided into two groups (control and experimental) and each group had 10 samples. The first group was made from clear acrylic resin without the addition of white oil paints, and the second group (experimental) comprised the addition of 1 ml of the white oil paints to acrylic samples. Such samples were prepared with dimensions of (80 mm X10 mm X4 mm) length, width, and thickness, respectively. All the samples were tested by the Charpy's impact strength test. They were exposed to the load till the fracture occurred. All the values were analyzed using SPSS version 20, and the independent T-test was used for comparison between the 2 groups. Results: A statistically significant decrease (P-value < 0.001) was found in the impact strength of acrylic resins after the addition of titanium dioxide oil paints (experimental group: 5.97 + 1.11, control group: 9.42+1.32 KJ/M2). Conclusion: This study concluded that the addition of titanium dioxide oil paint significantly reduces the impact of strength of the acrylic resin. It is suggested to use different stains which will have no negative effect on impact strength of the acrylic resin.

scholarly journals Damage Evolution of Granodiorite after Heating and Cooling Treatments

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 779
Author(s):  
Mohamed Gomah ◽  
Guichen Li ◽  
Salah Bader ◽  
Mohamed Elkarmoty ◽  
Mohamed Ismael
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Failure Mode ◽  
Physical And Mechanical Properties ◽  
P Wave ◽  
Physical Parameters ◽  
Slow Cooling ◽  
Heating And Cooling ◽  
Natural Rock ◽  
The Impact

The awareness of the impact of high temperatures on rock properties is essential to the design of deep geotechnical applications. The purpose of this research is to assess the influence of heating and cooling treatments on the physical and mechanical properties of Egyptian granodiorite as a degrading factor. The samples were heated to various temperatures (200, 400, 600, and 800 °C) and then cooled at different rates, either slowly cooled in the oven and air or quickly cooled in water. The porosity, water absorption, P-wave velocity, tensile strength, failure mode, and associated microstructural alterations due to thermal effect have been studied. The study revealed that the granodiorite has a slight drop in tensile strength, up to 400 °C, for slow cooling routes and that most of the physical attributes are comparable to natural rock. Despite this, granodiorite thermal deterioration is substantially higher for quick cooling than for slow cooling. Between 400:600 °C is ‘the transitional stage’, where the physical and mechanical characteristics degraded exponentially for all cooling pathways. Independent of the cooling method, the granodiorite showed a ductile failure mode associated with reduced peak tensile strengths. Additionally, the microstructure altered from predominantly intergranular cracking to more trans-granular cracking at 600 °C. The integrity of the granodiorite structure was compromised at 800 °C, the physical parameters deteriorated, and the rock tensile strength was negligible. In this research, the temperatures of 400, 600, and 800 °C were remarked to be typical of three divergent phases of granodiorite mechanical and physical properties evolution. Furthermore, 400 °C could be considered as the threshold limit for Egyptian granodiorite physical and mechanical properties for typical thermal underground applications.

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.

Effect of Wood Filler Concentration on Physical and Mechanical Properties of PLA-Based Composites

2021 ◽  
Vol 887 ◽  
pp. 110-115
Author(s):  
G.A. Sabirova ◽  
R.R. Safin ◽  
N.R. Galyavetdinov
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Composite Materials ◽  
Impact Strength ◽  
Wood Flour ◽  
Experimental Studies ◽  
Physical And Mechanical Properties ◽  
Filler Concentration ◽  
High Concentration

This paper presents the findings of experimental studies of the physical and mechanical properties of wood-filled composites based on polylactide (PLA) and vegetable filler in the form of wood flour (WF) thermally modified at 200-240 °C. It also reveals the dependence of the tensile strength, impact strength, bending elastic modulus, and density of composites on the amount of wood filler and the temperature of its thermal pre-modification. We established that an increase in the concentration of the introduced filler and the degree of its heat treatment results in a decrease of the tensile strength, impact strength and density of composite materials, while with a lower binder content, thermal modification at 200 °C has a positive effect on bending elastic modulus. We also found that 40 % content of a wood filler heated to 200 °C is sufficient to maintain relatively high physical and mechanical properties of composite materials. With a higher content of a wood filler, the cost can be reduced but the quality of products made of this material may significantly deteriorate. However, depending on the application and the life cycle of this product, it is possible to develop a formulation that includes a high concentration of filler.

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