X-ray Stress Measurement of Tungsten Fiber Reinforced Titanium Composite Produced by Spot Welding

Titanium is widely used as a high performance material for industrial fields, because it has been known excellent properties of light weight, high strength, corrosion resistance and so on. On the other hand, tungsten has much more high strength and heat resistance than titanium. In this study, the tungsten fiber reinforced titanium matrix (W/Ti composite) was produced by a new manufacturing technique which used the spot welding. Thought the conventional method to make the W/Ti composite commonly used a casting system within a large vacuum chamber, this spot welding method is not need to use the vacuum chamber and/or the high temperature furnace. The arranged tungsten fibers were held between titanium plates (thickness; 0. 5mm), and fixed by the spot welding. In this method, the tungsten fibers were not jointed with titanium matrix in perfectly such as the composite made by the casting method because of the partial jointing by the spot welding. Therefore, the spot welding rate against the whole plate surface area (coverage) became in maximum 100% to make up for the partial joint in this method. From the microscopic observation in the cross section of the W/Ti composite, it was conformed the good jointing in the whole position between the tungsten fiber and the titanium matrix. The testing samples of the W/Ti composite were prepared and estimated the strength characters by the tensile testing, and were compared with pure titanium. Finally, residual stresses in the W/Ti composite were measured by X-ray stress measurement method. The residual stresses were measured in the tungsten fiber and titanium matrix, respectively. These results of residual stresses were discussed by the simple elastic model.