Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Heat treatments

Effects of Welding Position, Heat Treatments, and Surface Roughness on the Fatigue Behavior of Welded Aluminum Alloys Using Friction Stir Welding

Shaker Sakran Hassan; Sadeq Hussein Bakhy; Athraa Ali Jawad

Engineering and Technology Journal, 2014, Volume 32, Issue 11, Pages 2773-2787

The present work is aimed to study the fatigue behavior of friction stir welding for the similar and dissimilar joints taking into account the effects of welding position, post welding heat treatments, and surface roughness. The materials were used AA2024T3 and AA6061T6. The maximum welding efficiency achieved at friction stir welding process was 62.8 % of the base metal for the similar 2024-T3 joint, and this value was improved by using post welding heat treatments and reach to 67.9%. Results showed that fatigue strength at 106 cycles depended strongly on welding line position where for welding line at a distance 0.35L from loading side, the reduction in fatigue limit with respect to 2024T3 base material was 45% for similar joint and 58% for dissimilar joints, and for welding line at a distance 0.7 L, the reduction in fatigue strength was 56% for similar joint and 67% for dissimilar joints. While, it was a large reduction in the fatigue strength reaching to 70% in both similar and dissimilar joint for the welding joint at a distance L (i.e at the fixing end). The heat treatments improved the fatigue strength about 31% more than non heat treatments of the similar 2024T3 joint by fsw at 0.7L in high cycle regime. Finally, the non-finishing samples showed a reduction in fatigue strength reaching to 10% more than the finishing samples of the similar 2024T3 joint at 0.7L.

Influence of Annealing, Normalizing Hardening Followed By Tempering And Laser Treatments on Some of The Static and Dynamic Mechanical Properties of Medium Carbon Steel

Sanna A. hafeed; AbdulKhaliq F. Hamood

Engineering and Technology Journal, 2010, Volume 28, Issue 21, Pages 6274-6287

This research illustrates the influence of different heat treatments on the mechanical properties such as stress-strain curves ,wear resistance and fatigue properties of medium carbon steel,. This steel was treated by annealing, normalizing, hardening followed by tempering and laser treatments. The bulk mechanical properties of ultimate ,fracture and yield tensile strength were evaluated. Surface mechanical properties of fatigue, wear resistance and hardness were evaluated as well. Microstructure of treated alloys also were inspected. Results showed that (hardened -tempered) steel had improved tensile strength,
fatigue{limit, life}, wear resistance, hardness then laser surface treated alloy, then the normalized alloy came in order ,but annealed alloy had the lowest mechanical properties. Annealing caused softening and growth of alloy structure. It was found that the microstructure of treated alloy play an important role in the improvement
or deterioration of bulk and surface mechanical properties and by analyzing the obtained results. For (Quenched -tempered) alloy found fine tempered martensititic structure, laser surface treated alloy had martensititic structure in the skin and ferritic- pearlitic structures in the core .Normalized alloy had ferriticpearlitic structures, Annealed alloy had coarse ferritic- pearlitic structures