In order to improve the service life of turbine blades with toothed crowns, the contact surface is surface strengthened and cladding welding is used to increase the wear-resistant layer. Compared with conventional cladding methods such as argon arc welding, laser cladding technology has the advantages of concentrated energy density, small heat-affected zone, small deformation, precise controllability, and easy automation. Therefore, laser cladding can be used as a new turbine blade tooth crown. The preferred solution for surface strengthening and repair of failed blades.

Technical craftsmanship

According to the working conditions of the material, two wear-resistant alloys, Co-Cr-W and Co-Cr-Mo, are generally used as materials for the cladding layer. This technology has been maturely used abroad, but there are not many practical applications in China. Huirui Chengdu’s technical team carried out process research on this technology many years ago and has successfully developed a laser cladding process for a certain model of blades. and independently developed aerospace engine laser cladding additive manufacturing equipment with independent intellectual property rights.

The special wear-resistant Tribaloy800 modified powder optimized by Huirui according to the process has good high-temperature wear-resistant strength and good weldability. After cladding, the appearance is smooth and the amount of modification is small; there is no obvious deformation after cladding; there are no macro cracks after fluorescence detection; there are no appearance defects such as collapse or incomplete cladding. Metallographic examination shows that the metallurgical bond between the cladding layers is good, with no pores, no unfusion, no obvious cracks, etc. Under the same corrosion conditions, the corrosion resistance of the cladding layer is much higher than that of the base material. Microhardness test results show that the hardness value of the cladding layer has far met the customer’s hardness requirements, with an average hardness >550HV (HRC53). The wear and corrosion resistance of the cladding layer meets the requirements of the surface strengthening layer.

To meet the tooth crown repair needs of 331, StelliteX-40 alloy powder cladding is used. After cladding, the blades have no obvious deformation; no macro cracks; no appearance defects such as collapse and under-fullness; the appearance is smooth and the amount of modification is small. From the metallographic diagram, it can be seen that the bonding boundary between the blade base material and the cladding layer is obvious, the structure of the fusion zone is clear and dense, the grain boundaries are clear, the crystal shape is needle-like and dendritic, the grain size is uniform, and there are no pores, cracks, or cracks in the cladding layer. Obvious defects such as lack of fusion. The hardness of the cladding layer is between 40~50HRC, which meets the hardness index required by customers.