Shanghai Optics and Machinery Institute has made new progress in laser welding of new high-temperature nickel based alloys

Recently, the research team of Yang Shanglu from the Laser Intelligent Manufacturing Technology R&D Center of the Chinese Academy of Sciences Shanghai Institute of Optics and Precision Machinery has made new progress in laser welding of new structural materials for high-temperature molten salts. The research team used a high-power laser for the first time to achieve defect free welding of nickel based high-temperature alloys, and conducted a systematic evaluation of the microstructure and mechanical properties of the welded joints.

The relevant research results were published in the Materials Characterization under the title "Laser welding of GH3539 alloy for molten salt reactor: processing optimization, microstructure and mechanical properties".

GH3539 alloy is a new type of high-temperature nickel based alloy independently developed in China, with excellent high-temperature mechanical and corrosion resistance, suitable for ultra-high temperature (≥ 850 ℃) molten salt environments. However, higher alloying results in higher welding crack sensitivity of the alloy.

In order to achieve efficient and high-quality laser welding of alloy structural components, the team used fiber laser welding technology to study the effects of different welding process parameters on the welding formation of GH3539 alloy with a thickness of 3mm. Through process optimization, the generation of welding cracks, pores, and other defects was suppressed. For the first time, defect free welding formation of GH3539 alloy was achieved. Based on this, the microstructure and mechanical properties at room temperature/high temperature of the welded joint were systematically evaluated; And analyzed the tensile fracture behavior of laser welded joints, elucidated the fracture mode of alloy laser welded joints. This work has laid the foundation for promoting the development of laser welding technology and the application of GH3539 nickel based high-temperature alloy.

Figure 1: (a) Welding cross-section of GH3539 laser welded joint; (b) Microstructure of GH3539 alloy; (c) XRD results of GH3539 alloy laser welded joints; (d) Hardness distribution of GH3539 alloy laser welded joints; (e) Engineering stress-strain curves of base metal and welded joints at different temperatures; (f) Average elongation of base metal and welded joints at different temperatures

Source: Shanghai Institute of Optics and Mechanics