scholarly journals Fracture Analysis of High-Strength Screw for Highway Construction

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1599
Author(s):  
Andrej Dubec ◽  
Petra Kováčiková ◽  
Jan Krmela ◽  
Vladimíra Krmelová ◽  
Artem Artyukhov
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Scanning Electron Microscopy ◽  
Fracture Surface ◽  
Central Area ◽  
High Strength ◽  
Material Contrast ◽  
The One ◽  
The Given ◽  
Scanning Electron

High-strength screws represent one of the main joining or fastening components which are commonly used in the process of installation of frame constructions for information boards or signposts, relating to the traffic roads. The control of the production process may not always be a sufficient method for ensuring road safety. The backward investigation and control of the screw material processing seems to be the one of the most important procedures when there is the occurrence of any failure during the operation of the screw. This paper is mainly focused on the analysis of the failure of the high-strength screw of 10.9 grade with M diameter of 27 × 3 and a shank length of 64 mm. The mentioned and investigated screw was used as a fastener in a highway frame construction. In the paper, there is mainly the analysis of the material for a broken screw in terms of the material micropurity, the material microstructure, the surface treatment as well as chemical composition. The evaluation was based on investigation by optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. Important knowledge and results were also obtained due to information on micromorphology and material contrast of the fracture surface resulting from fractographic analysis, using the method of scanning electron microscopy. In the case of the production of the high-strength screws, the tempering stands for the decisive or crucial process of heat treatment because the given process can ensure a decrease in hardness, while the required ductile properties of the material are kept and this is also reflected in the increase of strength and micromorphology of the fracture surface. From the aspect of micropurity, inclusions of critical size or distribution were not identified in the material, referring to Czech standard ČSN ISO 4967 (420471). The microstructure corresponds to tempered martensite, but the fracture surface of the broken screw was based on an intercrystalline micromechanism, which is undesirable for the given type of component. Combined with the measurement of the HV1 (Vickers hardness at a load of 1 kg) from the edge to the central area of the screw, the analysis revealed the significant drawbacks in the heat treatment of the high-strength screw.

Sellaphora labernardierei (Sellaphoraceae, Bacillariophyta), a new epilithic species from French spring and four new combinations within the genus Sellaphora

Phytotaxa ◽  
2016 ◽  
Vol 260 (3) ◽  
pp. 235 ◽  
Author(s):  
AUDE BEAUGER ◽  
CARLOS E. WETZEL ◽  
OLIVIER VOLDOIRE ◽  
ALEXANDRE GARREAU ◽  
LUC ECTOR
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Central Area ◽  
Mineral Waters ◽  
New Combinations ◽  
French Massif Central ◽  
Small Species ◽  
Massif Central ◽  
Floristic Survey ◽  
Scanning Electron

During a floristic survey of freshwater springs in the French Massif Central region, a new Sellaphora species (Bacillariophyceae) was found and is hereby described: Sellaphora labernardierei sp. nov. This new small species, with linear to linear-elliptical valves, slightly inflated in the middle, is formally described using light and scanning electron microscopy. The species has a single H-shaped chloroplast and striae usually biseriate tending to be uniseriate near the centre of the valve. The valve dimensions, the valve, pole and central area shapes, and the striae density and pattern allow their separation from similar taxa belonging to the genera Eolimna, Naviculadicta and Sellaphora. The ecological preferences of Sellaphora labernardierei are mineral waters with high nitrate concentrations. The examination of similar taxa belonging to the genera Eolimna and Naviculadicta and their characteristics lead to propose four new combinations of Sellaphora species.

Control of Cold Welding Cracks in 30CrMnSi Steel by Welding with Trailing Impacting and Rolling

2011 ◽  
Vol 295-297 ◽  
pp. 1251-1258 ◽  
Author(s):  
Jian Guo Yang ◽  
Lu Yong Huang ◽  
Hai Bo Pan ◽  
Xue Song Liu ◽  
Hong Yuan Fang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Welded Joints ◽  
High Strength ◽  
Cold Welding ◽  
Low Alloy Steel ◽  
Residual Welding Stress ◽  
Welding Stress ◽  
Scanning Electron ◽  
Main Factor

As a kind of the high strength low alloy steel (HSLA), 30CrMoSi has been used widely in some industrial fields. However, just like some HSLA, this steel also faces some problems when it is welded, especially such problem as cold cracking in the welded joints. In this paper, the cold welding cracks and microstructure of the joints of 30CrMoSi steel were studied by scanning electron microscopy (SEM) and optical microscopy (OM), and a method called welding with trailing impacting and rolling (WTIR) was utilized to solve the problem mentioned above by decreasing the residual welding stress which is one main factor to lead to cold welding crack in the joint of HSLA. The crack-free joints of 30CrMoSi steel were obtained by using proper parameters.

A new species of Neidiomorpha (Bacillariophyceae) from Dianshan Lake in Shanghai, China

Phytotaxa ◽  
2019 ◽  
Vol 423 (2) ◽  
pp. 99-104
Author(s):  
FEN LUO ◽  
QI YANG ◽  
KAIJUAN GUO ◽  
TENGTENG LIU ◽  
QUANXI WANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
New Species ◽  
Central Area ◽  
Diatom Species ◽  
Dianshan Lake ◽  
A New Species ◽  
Scanning Electron

A new diatom species, Neidiomorpha dianshaniana sp. nov., found in Dianshan Lake in Shanghai, China, is described herein. The morphology of N. dianshaniana has been documented by light and scanning electron microscopy. Neidiomorpha dianshaniana valves are elliptical in outline with rostrate apices. Raphe is almost straight and filiform. The axial area is narrow and linear. The central area is small, round to transversely elliptical or irregular. Striae are slightly radiate and almost parallel near the apices. Puncta are arranged in undulating longitudinal rows. Neidiomorpha dianshaniana’s most visible feature is its lack of central constriction, in which respect it differs from the three other species in the genus Neidiomorpha.

Novel Methods for Preparation and Surface Treatment of Nano-CaCO3

2013 ◽  
Vol 750-752 ◽  
pp. 336-339
Author(s):  
Fa Chao Wu ◽  
Teng Fei Shen
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Fourier Transform ◽  
Room Temperature ◽  
Transmission Electron ◽  
Reduce Energy Consumption ◽  
Scanning Electron

In this work, CaCO3 nanoparticles have been synthesized via heat-treatment of a new precursor. Effect of calcinations temperature on particle size has been investigated. The products were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). nanoCaCO3 was modified using chloroform as solvent and fatty acid as modifier atroom temperature. The advantage of this modification is that it can be proceed at room temperature and it can reduce energy consumption.

Two new centric diatoms (Bacillariophyta) from the sub-Antarctic region

Phytotaxa ◽  
2019 ◽  
Vol 394 (1) ◽  
pp. 50 ◽  
Author(s):  
BART VAN DE VIJVER ◽  
VÁCLAV HOUK
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Central Area ◽  
Soil Samples ◽  
Antarctic Region ◽  
Diatom Flora ◽  
Main Island ◽  
Centric Diatoms ◽  
Heard Island ◽  
Scanning Electron

During a survey of the limno-terrestrial diatom flora of the sub-Antarctic region, two unknown melosiroid diatom taxa were observed in several shaded, damp cave (moss and soil) samples from Heard Island and Ile de la Possession, the main island of the Crozet Archipelago. Comparison with already known species from the genus Melosira and the recently described genera Arcanodiscus, Angusticopula and Ferocia, resulted in the description of both new taxa based on detailed light and scanning electron microscopy. A first species was described as Ferocia subantarctica sp. nov. and can be distinguished based on its numerous, narrow girdle bands, relatively weakly domed valves, a limited number of well-developed spines and a rather large, hyaline central area. The second species, Arcanodiscus desmetianus Van de Vijver sp. nov., can be recognized based on its solitary frustules, a series of parallel ridges surrounding the mantle and a hyaline central area that is only less than 50% of the total valve diameter. Both taxa are morphologically and ecologically characterized and compared with all known melosiroid taxa worldwide.

Scanning Electron Microscopy Studies of Nitrile Rubber Fractured Surfaces

1980 ◽  
Vol 53 (2) ◽  
pp. 321-326 ◽  
Author(s):  
A. K. Bhowmick ◽  
S. Basu ◽  
S. K. De
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fracture Surface ◽  
Polymer Fibers ◽  
Tensile Fracture ◽  
Flow Lines ◽  
Tensile Fracture Surface ◽  
Test Conditions ◽  
Heat Buildup ◽  
Scanning Electron

Abstract The fracture surfaces of a NBR vulcanizate after different test conditions have been studied by scanning electron microscopy. It has been shown that failure surfaces manifest typical characteristics dependent on the nature of the test. Tensile fracture surface shows occurrence of two different tear rates in the case of a filled NBR vulcanizate, while tear fracture is characterized by a few long flow lines. De Mattia flexing leads to layering of polymer fibers. Heat buildup and abrasion tests generate a ribbed structure on the surface.

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