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Heat Treatment: Principles And Techniques by RAJAN, T. V., SHARMA, C. P., SHARMA, ASHOK PDF. Download ISBN: from PHI Learning. Buy Heat Treatment: Principles And Techniques by RAJAN, T. V., SHARMA, C. P., SHARMA, ASHOK PDF Online. ISBN from PHI Learning. Heat Treatment: Principles and Techniques T.V. Sharma, C.P. Sharma, and Techniques by T.V. Sharma, C.P. Sharma, Ashok Rajan Free PDF d0wnl0ad.
Most of the engineering properties of metals and alloys are related to their atomic structure, crystal structure and microstructure. Mechanical properties are structure-sensitive in nature and their magnitude depend largely on size, shape and distribution of various microconstituents. Equilibrium microstructure can be predicted for an alloy with the help of an equilibrium diagram. Mechanical properties can be changed by varying the relative proportions of microconstituents. In practice, change in mechanical properties is achieved by a process known as heat treatment. This process consists of heating a metal or alloy to a specific predetermined temperature, holding at this temperature for required time, and finally cooling from this temperature. All these operations are carried out in solid state.
It was concluded that the refined nano-grains with the size of — nm was found to be beneficial for Nb3Sn superconductor. Another study by Mathaudhu et al.
Moreover, Zhang et al. Nevertheless, there are no systematic investigations on the mechanical properties and wear performance of Ta treated by ultrasonic nanocrystalline surface modification UNSM technique [ 20 ]. The UNSM treatment used to be applied for various metallic materials, ceramics, Si wafer, various coatings to improve the friction behavior, wear and corrosion resistance, and fatigue strength through the presence of nanostructured surface layer with the refined nano-sized grains [ 21 , 22 , 23 , 24 , 25 ].
Interestingly, so far it was discovered that the hardness and wear performance of Ti-6Al-4V alloy was improved via UNSM treatment at a high temperature [ 26 ].
However, the hardness can be continuously increased with temperature, where a softening may occur as well. It is strongly believed, according to the results, that the role of a high-temperature UNSM in Ta-related applications, such as aerospace, nuclear, electrical, etc. Materials and Methods 2. Specimen Preparation Refractory Ta is rarely used since alloying makes other metals brittle, with an exception of steel, in which case it increases the ductility and strength.
Important properties of Ta are shown in Table 1. Table 1 Mechanical and physical properties of Tantalum Ta. UTS, MPa. Certainly, it will certainly not obligate you to take many pages.
Sharma, Ashok Rajan, why don't you tell to others about in this manner? Sharma, Ashok Rajan As recognized, here are great deals of lists that offer several kinds of books to collect. Simply prepare few time and also web links to get the books. Sharma, Ashok Rajan in a quite easy fashion. The study of heat treatment has assumed great significance because of the vital role heat treatment plays in achieving the designed characteristics in a given material.
This comprehensive and well-organized text skillfully blends the theoretical and practical aspects of heat treatment. It discusses, in rich detail, about heat treatment of commercial steels, cast irons and non-ferrous metals and alloys. The book also offers an in-depth analysis of topics such as nature of metals and alloys; principles of heat treatment of steels; heat treatment processes; possible defects, causes and remedies in heat treatment; and inspection and quality control in heat treatment.
This second edition of the successful text has gone through considerable modification on the basis of responses received. Additional figures have been added for greater clarity and understanding. Multiple choice questions and other pedagogically arranged questions help students to assess their subject knowledge.
Since polycrystalline grains are of different crystallographic orientations at the grain boundaries, a dislocation passing from one grain to another will have to change its direction of motion.
Such changes of direction causes impediment to dislocation movement, and increases both the yield strength and ultimate tensile strength. Because age hardening samples have the highest number of grain boundaries, dislocation movement becomes more and more difficult during plastic deformation.
This is responsible for highest yield strength and ultimate tensile strength observed in age hardening samples. Also, Al alloy used for this study contains about 5.
These two alloying elements lead to increase in the strength of this alloy through formation of MgZn2 precipitate within the structure as the result of aging heat treatment. This result corresponds with Du et al. Annealing sample has the highest percentage elongation followed by as-cast rapidly cooled , age hardening samples, and as-cast gradually cooled.
This is partly due to increase in grain coarsening which leads to an increase in the grain boundary area which increases the amount of energy required for the movement of dislocations required to cause fracture Thus, the material can withstand a higher plastic deformation before the final fracture. However, the percentage elongation of as-cast gradually cooled is very small because of embrittlement of Al alloy as a result of microsegregation of MgZn2.
As-cast gradually cooled sample has extremely high hardness as a result of its brittle structure. From the remaining three samples age hardening heat treatment samples has the highest hardness followed by as-cast rapidly cooled and annealed samples. The highest hardness values developed by age hardening samples can be attributed to precipitation of coherent and finely dispersed MgZn2 phases which serves as foreign atom or inclusion in the lattice of the host crystal in the solid solution; this causes more lattice distortions which makes the alloy harder.
In the previous study solid solution strengthening from elastic distortions is produced by substitutional atoms of Mg and Zn in aluminium matrix Hence, the main strengthening mechanism in these alloys is precipitation hardening by structural precipitates of MgZn2 formed during artificial ageing.
The precipitate particles act as obstacles to dislocation movement and thereby strengthen the heat-treated alloys. The impact strength followed the same trends as percentage elongation with annealing sample been the highest and as-cast gradually cooled sample been the least.
This is because impact strength is also a measure of material's ductility, and ductility is inversely related to strength Conclusions From the outcome of this study, there is formation of microsegregations of MgZn2 during the gradual solidification of aluminium alloy due to solute redistribution of Mg and Zn but this was suppressed during rapid solidification.
However, the microsegregations that were formed when it was gradually cooled are dissolved to form a homogeneous phase during the soaking period of heat treatment operations. As a result of age hardening heat treatment operation there is formation of small and finely uniform dispersed precipitate of MgZn2 in the aluminium matrix while coarse grains of MgZn2 phase was formed in aluminium matrix as a result of annealing heat treatment operation.
It has been found that rapid solidification process and heat treatment eliminate the formation of microsegregation, and significantly improved some mechanical properties.
Age hardening heat treatment operation was found to improve yield strength, ultimate tensile strength and hardness values but lower ductility and impact strength. On the other hand annealing heat treatment operation improves impact strength and ductility but lower yield strength, ultimate tensile strength and hardness values. Therefore, annealing treatment of the alloy will be suitable for applications involving high toughness and ductility while age hardening treatment will be suitable for applications that require high ultimate tensile strength, yield strength and hardness values.
Finally, it is concluded that the formation of microsegregation embrittle aluminium alloy, and subsequently have negative effects on its mechanical properties and its application. This can be addressed by rapid solidification and appropriate heat treatment process. References 1. Properties and selection. Structure, mechanical properties, and stress corrosion behaviour of high strength spray deposited series aluminium alloy. Materials Science Technology.
Effect of hardness test on precipitation hardening aluminium alloy T6. Chiang Mai Journal of Science. Smallman RE. Modern physical metallurgy. Rapid solidification processing of 7xxx aluminium alloys: a review.