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Title of Thesis

Automated Testing of Object Oriented Systems using VDM++ and UML Communication Diagrams

Author (s)
Abdul Shakoor
Institute/University/Department Details
GIK Institute of Engineering Sciences and Technology
Session
2007
Subject
Engineering Material
Number of Pages
110
Keywords (Extracted from title, table of contents and abstract of thesis)
Thermo mechanical, critical stress, austenitic matrix

Abstract

In the present work, a comparative study of the shape memory and thermo mechanical behavior of four alloys containing different amount of samarium have been carried out at a strain rate of 0.08x10-6s-1. After hot rolling, annealing and solution treatment, the alloy samples were tensile deformed at room temperature from 1% to 5% and were then recovered at 600 C for 20 minutes repeatedly for six times to complete six training cycles. It has been found that the addition of samarium strengthens the austenitic matrix, increases the c/a ratio and reduces the grain size. It has been noticed that the addition of samarium (0.64 wt. %) improves the shape memory effect when the alloys were strained from 1% to 5%. This improvement in shape memory effect presumably can be regarded as the increase in strength, increase in c/a ratio and absence of ά (martensite). It has been further noticed that when samarium contents are gradually reduced from 0.64 % to 0.21% the shape memory effect decreases. The decrease in shape memory effect by the decrease in samarium contents can be attributed to decrease in strength, decrease in c/a ratio and formation of ά (martensite). It has been further noticed that the shape memory effect decreases with the increase in amount of strain. It is found that thermo mechanical treatment (training) results in improvement of shape memory effect and has a significant influence on mechanical parameters like proof stress (σ 0.002), critical stress (σ0.0008) and strain hardening exponent. The improvement in shape memory effect by thermo mechanical treatment can be regarded as the effect of reduction in the values of proof stress and critical stress during training which facilitates the formation of ε (martensite). It has also been noticed that excessive training may result in the formation of ά (martensite) due to continuous softening of the alloy during training, thus degrading the shape memory effect. Finally, it has also been noticed that the addition of samarium increases the values of proof stress, critical stress and strain hardening exponent. Although the addition of samarium increases the values of proof stress, critical tress and strain hardening exponent yet it has not an adverse effect on shape memory effect.

 

 

 


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S. No. Chapter Title of the Chapters Page Size (KB)
  0    
1 1 Introduction  
  1.1 Preamble 1
  1.2 Aim and Objectives of the Dissertation 1
  1.3 Outline of the Dissertation 2
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2 2 Literature Survey  
  2.1 Iron Based Shape memory Alloys 4

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  2.2 Behavior of fcc to hcp Transformation 7
  2.3 Factors Affecting Shape Memory Effect 10
  2.4 Methods for Improvement of SME in Fe-Mn-Si Alloys 15
  2.5 Solid Solution Hardening 18
  2.6 Precipitation Hardening 26
  2.7 Centrifugal Casting 28
3 3 Material Equipment and Experimental procedure  
  3.1 Materials Development and Processing 38
  3.2 Mechanical Properties 43


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  3.3 Lattice Constants and c/a Ratio 43
  3.4 Thermo mechanical Treatment and Training 44
  3.5 Calculation of Shape Memory Effect 44
  3.6 References 50
4 4 Effect of Samarium Additions on Mechanical Properties  
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  4.1 Effect of Samarium Additions on Tensile Properties 53
  4.2 Effect of Samarium Additions on Hardness 55
  4.3 Effect of Samarium Additions on Lattice Constants 55
  4.4 Effect of Samarium on Grain Size 58
  4.5 Effect of Samarium on Transformation Temperatures 58
  4.6 Conclusions 60
5 5 Effect of Samarium Additions on Shape Memory Behavior  
  5.1 Introduction 62
  5.2 Improvement of Shape Memory Effect 62
  5.3 Effect of Deformation and Training on Shape Memory Effect 64
  5.4 Conclusions 72
  5.5 References 73
       
6 6 Effect of Samarium Additions on Thermo mechanical Behavior  
  6.1 Introduction 75
  6.2 Comparison of Thermo mechanical Behavior 75
  6.3 Conclusions 82
  6.4 References 83

 

 

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7 7 Effect of Samarium Contents on Shape Memory Effect  
  7.1 Shape Memory Behavior 87
  7.2 Conclusions 91
8 8 Summary of Results and Future Work 94