From MMGWiki
Thermomechanical Processing for Recovery of Desired <001> Fiber Texture in Electric Motor Steels
It is estimated that electric motors consume 60% of generated electricity so improvements in the efficiency of electric motors will have major energy savings. Increase in efficiency can be achieved in thin sheet of Fe-Si steel with optimum grain size of about 200 µm and a <100> fiber texture normal to the sheet, which maximizes the easy magnetization directions in the sheet. The Goss texture {110}<001>, that has a single easy magnetization direction in the Fe-Si sheet has been produced for electrical transformer applications for many years by thermomechanical processing, but the desired <100> fiber texture for electric motor application has not yet been produced by any thermomechanical processing route.
This technological challenge is being addressed through detailed studies of the deformation and recrystallization processes in directionally solidified and continuously cast Fe-Si alloys, with columnar grained structure with the desired <100> fiber texture. We have successfully developed a multi-step thermomechanical processing route that recovers preferred <100> fiber texture. Images below show initial texture, texture after conventional processing and texture obtained by novel processing, respectively.
Solute Enhanced Strain Hardening of Aluminum Alloys
Strain hardening, one of the oldest and most widely exploited strengthening mechanisms of metals, is largely ignored in aluminum based alloys. The reason for this is that aluminum alloys have a high stacking fault energy (SFE). Due to this high SFE the dislocations that are produced during plastic deformation are not as readily retained (dynamic recovery) as they are in other alloys. This has led the field to design alloys to effectively precipitation harden. It was later discovered that these solute rich alloys designed for artificial ageing exhibited higher strain hardening rates than anticipated, provided that the solute is kept in solution (T4 or W temper). This discovery has prompted the investigation of strain hardening and solute enhanced strain hardening of aluminum alloys.
The yield stress of commercial purity aluminum plotted against ECAP processed strain
Stress-Strain plot for compression testing done on post-deformation processed aluminum alloys
and the tabulated results showing the superior strengths achieved.
Through the use of industrial and novel deformation methods (cold rolling, pressing, ECAP) yield strengths previously unachievable in aluminum alloys have been realized. Commercial purity Al, processed to a true strain of 10 exhibits a yield strength of 180MPa but more impressively in alloy 2524 yield strengths as high as 620MPa have been achieved (the highest yield strength that can be produced by precipitation hardening this alloy is 430MPa). Studies are also being conducted on the effect of GP zone formation on strain hardening rate.
