Abdolhamid Azizi, , , ,
Volume 13, Issue 12 (2-2014)
Abstract
The aircraft aluminum alloys generally present low weldability by traditional fusion welding process. The development of the friction stir welding has provided an improved way of producing aluminum joints. In this present work the influence of process and tool parameters on strength properties of AA7075-T6 joints produced by friction stir welding was analyzed. Joints were fabricated by varying process parameters and tool parameters. Strength properties of the joints were evaluated and correlated with the microstructure and hardness of weld nugget. This investigation demonstrates, Joints fabricated at rotational speed of 1400 rpm and welding speed of 60 mm/min using the tool with 15mm shoulder diameter, 5mm pin diameter and 45 HRc tool hardness ,yielded higher strength properties.
Mahdi Karimi Manesh, Iraj Sattari Far, Hamid Omidvar,
Volume 15, Issue 2 (4-2015)
Abstract
Using in low temperatures causes embrittlement of many structures, consequently, selection of welding parameters for maintaining the toughness of welded structures, is so important. In this paper, effects of arc heat input and welding speed on the cryogenic impact strength of type 304L austenitic stainless steel weld metal, are investigated. For this purpose, 304L austenitic stainless steel sheet with 5 mm thickness, was welded with gas tungsten arc welding process and by changing the parameters of arc heat input and welding speed, the effect of these parameters on the microstructure, the weld metal ferrite content and low temperature charpy impact energy of samples, was determined. The arc heat input range applied was between 1.04 and 3.23 kW, and the welding speed varied between 30 and 240 mm/min. It was found that, increasing of arc heat input can reduce weld metal ferrite content, which improves low temperature impact strength, but on the other hand, slow cooling due to increasing heat input results in coarser dendritic structures in the weld metal, and can adversely affect on impact strength. Changes of Welding speed can also affect on the amount of ferrite and microstructure and thus have influence on the impact strength. Finally having carried out the numerous tests, optimum impact properties at low temperature, were obtained at 1.67 kW arc heat input and 120 mm/min welding speed.
M. Salavati, Y. Mazaheri, M. Sheikhi,
Volume 19, Issue 10 (10-2019)
Abstract
The Nd: YAG pulsed laser welding process with different speed and shielding gas was applied on 2205 duplex stainless steel. The effects of different parameters on the microstructural evolutions and mechanical properties were investigated. Four different zones with different secondary austenite contents were observed in the weld microstructure. By changing the shielding gas from argon to nitrogen, the secondary austenite percentage was not significantly varied. The secondary austenite fraction was showed about 38% reduction with increasing the welding speed. The weld penetration depth decreased with changing the shielding gas from argon to nitrogen (about 26% and 14% reduction at speed of 3.8 and 8.3 mm/s, respectively) and increasing the welding speed (about 43% and 34% reduction under shielding gas of argon and nitrogen, respectively). The variations in microhardness values along the weld line were correlated to the microstructural characterizations. Changing the welding speed had no significant effect on the microhardness variations, but changing the shielding gas from argon to nitrogen caused a significant increase of microhardness.
