| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 100 === Nickel-based superalloy Inconel 738 has been applied as a material for gas turbine blade due to its excellent mechanical strength and anti-corrosion ability in high temperature operation environment. After long time service, blade surface or top of seal ring area could be damaged cause of high temperature fatigue, corrosion, creep and foreign object damage (FOD). In order to reduce operation and maintenance costs, typically use lower strength powder such as Inconel 625 with coaxial laser to repair the slight damage blade. However, it shall use Inconel 738 powder to repair the top of seal ring which needs strength as high as base metal .
Due to poor weldability, it could occur solidification crack and HAZ liquation crack when Inconel 738 powder clad on the Inconel 738 BM without high pre-heat temperature. This study is to find out parameter of laser cladding with high pre-heat temperature, and use X-ray residual stress analyzer to watch for changes in residual stress of weldment after cladding and heat treatment, and finally verify the strength of cladding layer with high temperature tension test and creep rupture test.
The results reveal that the specimen of Inconel 738 blade cladded with pre-heat temperature of 780~900℃, laser power 1800W and travel speed 900 mm/min, will get approximate strength to base metal without solidification crack, so that high temperature laser cladding can be applied in practical repair of Inconel 738 gas turbine blades.
|
|---|
