Mechanical Nanocrystallization Surface Treatment on the Reheated 400MPa Ultrafine Grained Steel

2009 ◽  
Vol 79-82 ◽  
pp. 377-380
Author(s):  
Hong Yun Zhao ◽  
Guo Dong Wang ◽  
Chun Hua Xu ◽  
Feng Yuan Shu
Keyword(s):  
Mechanical Properties ◽  
Surface Treatment ◽  
Room Temperature ◽  
Performance Testing ◽  
Surface Form ◽  
Test Results ◽  
Ultrafine Grained ◽  
Before And After ◽  
Different Temperatures ◽  
Ultrafine Grained Steel

After reheated at different temperatures for 5 minutes, the 400MPa Ultrafine Grained Steel specimens were air-cooled to room temperature, and then carried out the mechanical nanocrystallization surface treatment and structure performance testing. On the basis of comparing the test results on the specimens before and after the mechanical nanocrystallization surface treatment, the process of mechanical nanocrystallization was analyzed briefly. The results show that: as the reheating temperature rising, the trend of grain size growing increases markedly, and the mechanical properties also drop down to different degrees; when the reheating temperature is around 800°C, because of the pearlite spheroidized significantly, its mechanical properties drop the most seriously; after the mechanical nanocrystallization surface treatment, not only its surface form a layer of fine nano-layer (about 100 nm) structure, but also its mechanical properties rise obviously, and the yield strength is over 450MPa.

scholarly journals STUDY ON REINFORCEMENT OF FABRICATED HOLLOW SLAB BRIDGE BY POLYURETHANE-CEMENT COMPOSITE (PUC)

2021 ◽  
Vol 30 (2) ◽  
Author(s):  
Kexin Zhang ◽  
Tianyu Qi ◽  
Zhimin Zhu ◽  
Xingwei Xue
Keyword(s):  
Mechanical Properties ◽  
Surface Treatment ◽  
Bearing Capacity ◽  
Failure Mode ◽  
Concrete Structures ◽  
Cement Composite ◽  
Test Results ◽  
Before And After ◽  
Load Tests ◽  
Short Time

In this paper, a new polyurethane-cement composite (PUC) material is used to reinforce a 25-year hollow slab bridge. PUC material is composed of polyurethane and cement, which has good mechanical properties. After pouring PUC material at the bottom of the hollow slabs, the traffic can be restored in a short time. Ultimate bearing capacity was discussed based on the concrete structures. The failure mode of the reinforced beam depends on the PUC material. The strengthening process includes surface treatment of concrete, formwork erection and polyurethane cement pouring. In order to verify the effectiveness of PUC reinforced bridges, load tests were carried out before and after reinforcement. The test results showed that PUC could remove the bridge load and increase the stiffness of the hollow slabs.

Sunlight exposure: the effects on the performance of paragliding fabric

2018 ◽  
Vol 69 (05) ◽  
pp. 381-389
Author(s):  
MENGÜÇ GAMZE SÜPÜREN ◽  
TEMEL EMRAH ◽  
BOZDOĞAN FARUK
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Air Permeability ◽  
Sunlight Exposure ◽  
Test Results ◽  
Coating Materials ◽  
Strength Tests ◽  
Before And After ◽  
The Relationship ◽  
Dark Blue

This study was designed to explore the relationship between sunlight exposure and the mechanical properties of paragliding fabrics which have different colors, densities, yarn counts, and coating materials. This study exposed 5 different colors of paragliding fabrics (red, turquoise, dark blue, orange, and white) to intense sunlight for 150 hours during the summer from 9:00 a.m. to 3:00 p.m. for 5 days a week for 5 weeks. Before and after the UV radiation aging process, the air permeability, tensile strength, tear strength, and bursting strength tests were performed. Test results were also evaluated using statistical methods. According to the results, the fading of the turquoise fabric was found to be the highest among the studied fabrics. It was determined that there is a significant decrease in the mechanical properties of the fabrics after sunlight exposure. After aging, the fabrics become considerably weaker in the case of mechanical properties due to the degradation in both the dyestuff and macromolecular structure of the fiber

Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations

2006 ◽  
Vol 503-504 ◽  
pp. 31-36 ◽  
Author(s):  
Johannes Mueller ◽  
Karsten Durst ◽  
Dorothea Amberger ◽  
Matthias Göken
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Fcc Metals ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Indentation Strain

The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.

scholarly journals Do Rescuers’ Physiological Responses and Anxiety Influence Quality Resuscitation under Extreme Temperatures?

2020 ◽  
Vol 17 (12) ◽  
pp. 4241 ◽  
Author(s):  
José Luis Martin-Conty ◽  
Francisco Martin-Rodríguez ◽  
Juan José Criado-Álvarez ◽  
Carmen Romo Barrientos ◽  
Clara Maestre-Miquel ◽  
...  
Keyword(s):  
Room Temperature ◽  
Real Life ◽  
Health Sciences ◽  
Extreme Heat ◽  
Cross Sectional ◽  
La Mancha ◽  
Life Circumstance ◽  
Before And After ◽  
Different Temperatures ◽  
Academic Year

Teaching and training cardiopulmonary resuscitation (CPR) through simulation is a priority in Health Sciences degrees. Although CPR is taught as a simulation, it can still be stressful for the trainees since it resembles a real-life circumstance. The aim of this study was to assess the physiological effects and anxiety levels of health sciences undergraduates when faced with CPR process in different temperatures (room temperature, extremely cold, or extremely warm). This was a descriptive cross-sectional before–after study conducted during the 2018/2019 academic year with 59 students registered in the Faculty of Health Sciences of the Castilla-La Mancha University (UCLM). State Trait Anxiety Inventory (STAI) questionnaires were distributed among the students before and after the CPR simulation. We found greater level of situational anxiety in undergraduates faced with extreme adverse temperature scenarios (extreme heat and cold), especially in conditions of extreme heat compared to controlled environment (at room temperature). We discovered differences regarding sex, in which men scored 6.4 ± 5.55 points (STAI after CPR score) and women scored 10.4 ± 7.89 points (STAI after CPR score). Furthermore, there was less lactate in blood, before and during the event in individuals with anxiety. In addition, beginning in Minute 7, we observed a remarkable decrease (but not significant) in the performance of rescuers with anxiety. Programs targeted at promoting coping mechanisms to reduce anxiety before a critical clinic situation should be implemented in academic training.

Effects of Temperature and Strain Rate on Compressive Mechanical Properties of Ultrafine-Grained CP Titanium

2007 ◽  
Vol 26-28 ◽  
pp. 381-384 ◽  
Author(s):  
Zhi Guo Fan ◽  
Chao Ying Xie
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Ultimate Strength ◽  
Room Temperature ◽  
Equal Channel Angular Extrusion ◽  
Coarse Grain ◽  
Ultrafine Grained ◽  
Effects Of Temperature ◽  
Cp Ti ◽  
Compressive Tests

Ultrafine-grained (UFG) CP Ti were successfully prepared by Equal Channel Angular Extrusion (ECAE) at 390°C~400°C, small than 0.5 um in size. The compressive tests for coarse grain (CG) and UFG Ti were carried out at room temperature (RT) and 77K. UFG Ti showed excellent ductility and higher strength than CG Ti at RT and 77 K. The strain hardening of UFG Ti was improved at 77 K. The compressive ultimate strengths of CG Ti and UFG Ti were both enhanced as the strain rate increased, but CG Ti showed more obvious temperature and strain rate dependence of flow stress, comparing with UFG Ti. When the strain rate increased to 1×10-1/s, the compressive ultimate strength of UFG Ti was kept almost constant, while the ultimate strength of CG Ti increased to the strength level of UFG Ti.

Preparation of Al2O3/Al-Si Composites by In Situ Reaction of Fe2O3+MnO2/Al System

2015 ◽  
Vol 816 ◽  
pp. 48-53
Author(s):  
Jing Zhang ◽  
Hua Shun Yu ◽  
Xin Ting Shuai ◽  
Hong Mei Chen ◽  
Guang Hui Min
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Electron Probe ◽  
Room Temperature ◽  
Manganese Content ◽  
Hardness Test ◽  
Test Results ◽  
Electron Probe Micro Analyzer ◽  
Transmission Electron ◽  
Polygonal Shape

Al2O3 particles reinforced ZL109 composites were prepared by in-situ reaction between Fe2O3+MnO2 and Al in this paper. The influence of ratio of Mn to Fe on the morphologies of Al-Si-Mn-Fe phase and mechanical properties of the composites was investigated. The microstructure was studied by electron probe micro-analyzer (EPMA) and transmission electron microscopy (TEM). The results show that the Al2O3 particles displaced by the Fe2O3+MnO2/Al system are in nanosize. The acicular Al-Si-Fe phases change from acicular to polygonal shape and become smaller with the increase manganese content. The hardness test results have no big difference on the composites. However, the ultimate tensile strength at room temperature and 350°C enhance evidently with the increasing of Mn/Fe.

Microstructure and Mechanical Properties of Mg-RE-B Alloys

2011 ◽  
Vol 311-313 ◽  
pp. 2251-2254
Author(s):  
Le Ping Bu ◽  
Qing Tai Shen ◽  
Pei Wu
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Room Temperature ◽  
Tensile Yield Strength ◽  
Ingot Metallurgy ◽  
Particle Structure ◽  
Promising Candidate ◽  
Excellent Mechanical Property ◽  
Before And After ◽  
Microstructure And Mechanical Property

The best is to read these instructions and follow the outline of this text. Mg-RE-B alloy with minuteness particle structure (MPS) were prepared by ingot metallurgy including as-cast and hot-extruded processing, and the microstructure and mechanical property of Mg-6RE-3B2O3 (wt%) alloys were investigated before and after hot-extruded. The Mg-RE-B alloy has satisfied grain size and particle structure, went with excellent mechanical property of tensile yield strength of 520 MPa and elongation of 5% at room temperature. The MPS Mg-RE-B alloy is a promising candidate among lightweight structural materials

Wandering of Crosslinks in Rubber at High Temperature

1959 ◽  
Vol 32 (3) ◽  
pp. 696-700
Author(s):  
M. J. Voorn ◽  
J. J. Hermans
Keyword(s):  
Stress Relaxation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Crosslinking Density ◽  
Heat Treated Sample ◽  
Equilibrium Degree ◽  
Heat Treated ◽  
Before And After ◽  
Final Stress ◽  
Different Temperatures

Abstract There are strong reasons to believe that on heating a crosslinked rubber crosslinks are broken and new ones formed. This has been established by the well-known work on stress relaxation of Tobolsky and his school, and others. In the following we will discuss some experiments which give further support to these views, both of a qualitative and quantitative nature. In the first place, we carried out a few preliminary experiments on stress relaxation at elevated temperatures. This stress relaxation may be due to either or both of two effects : (a) a displacement of the crosslinks, (b) a change in the number of crosslinks per unit of volume (crosslinking density p). A measure of ρ can be obtained from the equilibrium degree of swelling at room temperature, and this gives us a means of comparing changes of ρ in a stretched sample with those occurring in the unstretched state. To this end commercial rubber strips were heated in the stretched state in the absence of oxygen at three different temperatures (80, 106, 122° C) for times varying from 2 to 72 hours. The degree of stretch, i.e., the length of the stretched rubber divided by the original length was α=1 (unstretched) in one series, and α=3 in a second series. The initial stress τ0 (for α=3) and the final stress τ at the end of the heating period were read from the stress-strain diagrams, taking into account that for the heat-treated strips there was a permanent set. In other words, τ is the stress needed to give the heat-treated sample at room temperature a length 3 times the length of the original untreated sample; the ratio τ/τ0 is therefore essentially the ratio between the moduli of elasticity. The cross-linking densities ρ0 and ρ before and after heating were derived from swelling experiments (for details see the sections on swelling).

Mechanical Properties of Winding Conductors Affected by Cyclic Thermal Overloads

2006 ◽  
Vol 113 ◽  
pp. 541-544 ◽  
Author(s):  
N. Višniakov ◽  
J. Novickij ◽  
D. Ščekaturovienė ◽  
M. Šukšta
Keyword(s):  
Mechanical Properties ◽  
Metal Matrix ◽  
Room Temperature ◽  
Pure Copper ◽  
Testing Machine ◽  
Liquid Nitrogen Temperature ◽  
Ultimate Tensile Stress ◽  
Climatic Chamber ◽  
Fast Heating ◽  
Before And After

The influence of thermal cyclic overloads on mechanical properties of winding conductors was investigated. Copper-niobium microcomposite, soft and hard pure copper wires were conditioned at temperatures range from 77 K to 500 K. The treatment was done during 100 cycles of fast conductor cooling to liquid nitrogen temperature and further fast heating in a climatic chamber. The ultimate tensile stress limit and the elongation at failure of metal-matrix copper-niobium microcomposite, soft and hard copper wires were measured before and after thermal treatment with a testing machine at room temperature.

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