The Impact of Heat Input on the Microhardness and the Micro-structure of a Welded Carbon Steel and the Modeling of its Micro-crack | Chapter 2 | Current Approaches in Engineering Research and Technology Vol. 2

 The welding process induces changes in the Heat-Affected Zone (HAZ) owing to thermal effects. This implies alterations in mechanical properties and microstructure based on the magnitude of absorbed heat and cooling time. The analysis presented in this article reveals that the base metal, initially composed of ferrite and pearlite, undergoes a change in grain size after welding. During welding, the heat produced during the process can affect the microhardness and the microstructure of the material. The change in the microstructure and the microhardness can be discovered by carrying out a microhardness test on the welded sample and comparing changes in the three different zones i.e the base, the weld and the Heat affected zone (HAZ), or by carrying out a microstructural examination on the welded sample and see the grain dispersion in relation to their sizes. In this work, the weld quality of manual arc welded samples of low-carbon steel St3sp destined for bridge construction to be used in Cameroon has been investigated. After a chemical analysis of the material, a microhardness test and a microstructural examination were also done. Results show that a composition of pearlite and ferrite was seen with a composition of 20/80 respectively. For weld zone and HAZ it changes due to thermal processes. So the micro-structure analysis shows that the base metal is a ferrite and pearlite having a grain size of 11-12 on a scale corresponding to an average grain diameter ≈of 7 microns. The structure of the weld metal is also made up of ferrite and pearlite with columnar crystals of cast metal. The HAZ is made up of Widmanstätten. The width of the HAZ zone is about 1,5mm in different areas of heat affected zone and is observed fine-grained ferrite-pearlite structure with a high degree of dispersion. A micro-crack was revealed with a length of 1,7 mm in the HAZ of sample number 7 and a 1,2 mm length of micro-crack in the weld zone of this same probe was also revealed. The modeling of the micro-crack shows that the velocity of its propagation in the welded zone is higher as much than that in the heat-affected zone i.e. in the welded zone is estimated at 64.59m/s, while in heat affected zone is 0,354.1 m/s. This means that in the absence of welded and environmental defects, failure of structure will be common in the welded zone.

 

Author(s) Details:- 

 

 Mbelle Samuel Bisong
Department of Mechanical Engineering, College of Technology University of Buea, P.O. Box: 63, Buea, Cameroon and Department of Mechanical Engineering, ENSET Douala, P.O. Box: 1872, Douala, Cameroon.

 

Kevin Tsapi Tchoupou
Department of Mechanical and Industrial Engineering, National Higher Polytechnic Institute, University of Bamenda, P.O Box, 39 Bambili, Cameroon.

 

Valeriy V. Lepov
Larionov Institute of Physical-Technical Problems of the North, FRC YSC SB RAS, 1, Oktyabrskaya, 677007 Yakutsk, Russia.

 

Kisito Pierre
Department of Physics, LMMSP University of Dschang, P.O. Box: BP 96, Dschang, Cameroon.

 

Please see the link here:-  https://doi.org/10.9734/bpi/caert/v2/7425B

Cracks and Fractures in Teeth | Book Publisher International

When a crack develops in a tooth, it is referred to as a fractured tooth or cracked tooth syndrome (CTS). Sometimes the crack will be little and unharmful. Sometimes it might lead to the tooth splitting or breaking.

Although anybody can shatter a tooth, youngsters and the elderly are more prone to tooth fractures. Cracks might appear in the root or the crown. The root and the crown both have numerous layers:

Enamel: A rough, white exterior.

Dentin: The tooth's middle layer.

Pulp: Soft inner tissue that houses nerves and blood vessels.

Some or all of these layers may be impacted by tooth fractures. The location and degree of the fracture determine the course of treatment for a broken tooth. Even though some fractures go unnoticed, a fractured tooth may pain or feel sensitive. The likelihood of healing a fractured tooth rises with earlier treatment.

Author(s) Details:

Shahd Fawaz Alnojaidi

Dar Al Uloom University, Riyadh, Saudi Arabia and Massachusetts Central University, USA.

Ghadeer Fawaz Alnojaidi

Dar Al Uloom University, Riyadh, Saudi Arabia.

Rahaf Fawaz Alnojaidi

Dar Al Uloom University, Riyadh, Saudi Arabia.

Sawsan M. Alyousef

Intensive Care Consultant, King Fahad Medical City, Princess Noura University, Riyadh, Saudi Arabia.

View Book: https://stm.bookpi.org/CFT/article/view/7416

Approximate Determination of J Integral for Cracked Structures | Chapter 4 | Recent Trends in Chemical and Material Sciences Vol. 9

The Js procedure of the French RCC-MR construction code, here referred to as the FC method, is contrasted with the GSM method for the assessment of the J integral of cracked components subjected to uniform normal stress, for centre cracked plates, single edge cracked plates, double edge cracked plates, and longitudinally cracked pipe produced from X70 steel. The EPRI approach was used to determine the "reference" values for the J integral for broken plates. The study's major goal was to demonstrate that the GSM approach can accurately forecast the J integral for broken plates and pipes. Although the GSM technique findings are often a little more cautious than those anticipated by the FC method, a comparison of outcomes produced using the GSM and FC methods demonstrates that both approaches offer comparable results. When compared to the "reference" values of the J integral, both methodologies produce conservative findings for the majority of fracture configurations, while estimates for fractures with a relative length of less than 1/8 were not found to be as conservative. The two methods were also used to forecast external longitudinal semielliptical part-through fractures in X70 steel pipe. The magnitudes of the anticipated burst pressures were remarkably comparable to one another and conservative when compared to FEM calculations and empirically determined burst pressures.

Author(s) Details:

Lubomir Gajdos,

Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences, v. v. i. Prosecká 809/76, 190 00 Prague, Czech Republic.

Martin Sperl,

Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences, v. v. i. Prosecká 809/76, 190 00 Prague, Czech Republic.

Jiri Kuzelka,

Faculty of Mechanical Engineering, Czech Technical University in Prague, Technická 4,166 07 Prague, Czech Republic.

Jan Kec,

SVUM a.s., Tovarni 2053, 250 88 Celakovice, Czech Republic

Please see the link here: https://stm.bookpi.org/RTCAMS-V9/article/view/7377