Research On The Technology And Structure Property Of Spray Formed 7xxx Aluminum Alloy In Friction Stir Welding

Compared with the traditional casting technology, the spray forming technology has the advantages of fast cooling speed, according to related report it can obtain 102～103K/s, the element of materials produced by spray forming technique has large solid solubility, tiny grains, well-distributed microstructure and little segregation. Spray formed 7xxx aluminum alloy has very high strength and plasticity, its combination properties keep ahead all over the world, it has the highest strength in all the maturate alloys in the present.In the experiment study of this paper, adopted muddler of three different geometry shapes produced by 9341 tool steels. By taper muddler with screw thread concave plane and under reasonable welding parameters condations is able to get the weld without any defects, the weld formation is good. In the experiment of technology optimization, changed the welding speed and rotation speed, ascertain effect of tenchnique parameters on the butt jointing tension strength. For spray formed 7475 aluminum alloy, when the muddler rotation speed(S) is 1200 r/min, welding speed (F) is 80mm/min, it will be reach the highest value of 442 MPa. For spray formed 7055 aluminum alloy, with constant welding speed (F) of 80mm/min, when the muddler rotation speed(S) is 800～1200 r/min, the mechnical property is good and stable, when the muddler rotation speed(S) is 1000 r/min, welding speed(F) is 100mm/min, the strength abtained highest value of 455 MPa.In this paper also analyzed the rupture pattern of spray formed 7475 aluminum alloy weld joint, carried out the microstructure and micro-rigidity experiment. Find that spray formed 7475 aluminum alloy has the traditional rolling microstucture, the crystalloid show the directional shape of batten remarkablely. In the metallographic phase experiment, find that, stretching workpiece of spray formed 7475 aluminum alloy break at the thermal mechnical affected zone, the workpiece after break has slight neck reduce, but not remarkable. Most part of the rupture section is toughness dimple area, the stretching rupture section is blending rupture section, the weld break is blending break. The lowest value for weld micro-rigidity of spray formed 7475 aluminum alloy appeared in the advancing side, it shows that the advancing side is the weld weakness area, this is related to the position of weld rupture section.FSW technique is one of the most representational advanced three large technology in welding technique field in 21st century, adopt the most new welding technique to weldability study on new materials of spray formed 7xxx aluminum alloy has an important innovation significance.