Fabrication of gradient-structure CuNiBe alloy bars by laser remelting and water-cooling

ABSTRACT

Laser remelting (LR) is a typical laser manufacturing technique. In this study, LR was used to fabricate gradient-structured CuNiBe alloy bars. A series of LR experiments with different parameters (such as the output power of the laser transmitter, scanning speed, and cooling condition) and subsequent aging treatments were designed. The remelted zone depth (RZD), the hardness with depth on the plane perpendicular to the LR track, the microstructure, and the precipitation characteristics of different zones of the remelted samples were analyzed. The results showed that the RZD increased with a higher output power of the laser transmitter and lower scanning speed. The hardness of the CuNiBe was significantly improved by the LR and subsequent aging treatment. A remelted zone (RZ) and heat affected zone (HAZ) were found in the remelted surface layer, and equiaxed substructures and columnar substructures were present in the RZ. Well-dispersed NiBe precipitates on the substructure boundaries in the transitional area between the RZ and HAZ were the main cause of strengthening of the sample that underwent LR without water-cooling. The strengthening effect was significantly enhanced by the refined grains for the sample that underwent LR with water-cooling.

KEYWORDS:

• Laser
• remelting
• aging
• cooling
• gradient-structure
• CuNiBe
• copper
• alloys
• microstructure
• precipitation
• mechanical
• property

Acknowledgments

The authors thank for the financial support by National Natural Science Foundation of China (Grant number: 51674303), National Youth Thousand Plan Program of China, Huxiang High-Level Talent Gathering Project of HUNAN Province (Grant number: 2018RS3015), Innovation Driven Program of Central South University (Grant number: 2019CX006), and the Research Fund of the Key Laboratory of High Performance Complex Manufacturing at Central South University.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51674303];Innovation Driven Program of Central South University [2019CX006];Huxiang High-Level Talent Gathering Project of HUNAN Province [2018RS3015].