| As the main and important aircraft materials,titanium alloy has been widely used.The main research object is TC4 alloy which was used as the plane wing arm material.This study is based on wing aircrafr in flight by circulating resistance.So the fatigue performance is very important.Using welding structure to replace forging structure can cost saving,improve materical utilization ,and so on.We study the welding process including TIG ,A-TIG ,LSND-TIG ,U-TIG and so on.At the same time,we can through some improving measures to lower residual stress,reduce weld defects,improve the fatigue life.Through measuring the residual stress that we can learn about the deformation effect and stress level were caused by these kinds of welding process. We can study the fatigue properties and prevent fatigue fracture failure through the above result.Through the experimental measurement,we found that heat treatment can effectively reduce the residual stress.at the same time,LSND-TIG can effectively reduce the welding deformation and lower residual stress peaks. But for the U-TIG+A-TIG,welding will produce many residual tensile stress.All kinds of welding process can obtain the similar residual stress distribution of the longrtudinal trend.And transverse distribution of residual stress are complex.We need to do further explored.Through the experiment, we found the improvement measures are remarkable.For LSND-TIG, in low stress range,improving longevity is ten times the TIG, but in the high stress area,the LSND-TIG U-TIG will reduce effect for fatigue life along with stress increases.Through the study of fracture with SEM,we found that the source faults is always in weld surface and weld edge.these regions exist stress concentration and welding defects.Faults are generally from thess place or the stomata and slag inclusion in the weld line to start. All of these research results for welding technology application in aircraft have very good promotion effect and great significance.
|
PDF Full Text Request