Stainless materials are among the most commonly used materials in nuclear power and aerospace engineering due to their excellent machinability and corrosion resistance properties. In most applications involving stainless steel materials, the stainless-steel parts usually comprise tailor-welded blanks (TWBs). These are a collection of partially finished metal sheets made of two thin metal plates with different thicknesses or materials. They are known for their relatively low cost and environmentally friendly nature, which significantly benefit weight reduction applications. Among the available TWB fabrication methods, laser welding technology has been identified as a promising method for the efficient production of high-quality TWBs. Compared to other methods, laser welding enables perfect control of the processing region, provides high energy density, and requires less heat input.
The application of laser technology for welding stainless-steel TWBs has been extensively studied in the past few years. For instance, butt joint welding of TWBs has provided remarkable results. However, this method requires high butt-joint accuracy and edge quality to prevent the possible occurrence of defects in the weld bead. This results in a trade-off between the processing complexity and the production yield. For example, during the welding processes, 304 stainless steel (304SS) may cause different problems such as thermal cracks and carbide precipitation that further compromise the quality and functionality of the welded parts. Notably, keeping the TWBs of high quality is vital to achieving the desired properties and ultimate functionality. Unfortunately, despite the impressive progress, welding strategies for solving these issues to improve the TWB fabrication process are sparsely investigated.
To address these issues, researchers at the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences: Professor Hongbo Zhu, Professor Yongqiang Ning and Professor Lijun Wang in collaboration with Professor Guangyi Ma and Professor Dongjiang Wu from Dalian University of Technology proposed a novel eave-like welding model for welding 304 stainless-steel (304SS) TWBs with different thickness. The main objective was to make the TWB welding process simpler and more efficient. In the experiment, they successfully processed the 2kW high-brightness semiconductor laser developed by themselves for unequal thickness plates. This semiconductor laser with high beam quality ensured the reliability of high-quality cutting and welding process. Corresponding experimental investigations were also conducted to validate the feasibility of the proposed model. Also, the microstructure and mechanical strength of the welded bead were analyzed via scanning electron microscope and energy dispersion spectrometer to evaluate their performance and potential industrial application. Their research work is currently published in the journal, Optics and Lasers in Engineering.
Results demonstrated the feasibility of the proposed eave-like model in welding stainless steel TWBs. Based on the novel welding model, the butt welding of 304SS TWBs with a plate thickness combination of 1.0 mm and 2.0 mm was successfully achieved using diode laser sources. The microstructure and tensile strength analysis results revealed that the welded TWBs were of high quality and could satisfy the requirements for different industrial applications like aircraft manufacturing. Compared to other methods, this approach is relatively simple and cost-effective.
In a nutshell, a new outstanding and efficient welding approach to improve the fabrication of 304 stainless-steel TWBs with different thicknesses was proposed and successfully validated. More importantly, this work also promotes the application of semiconductor laser technology. From the results, the proposed strategy sufficiently addressed the inherent challenges associated with the existing methods to produce high-quality welded 304SS TWBs. This indicated its capability to simplify the fabrication processes and enhance production efficiency for large-scale industrial applications. In a statement to Advances in Engineering, Professor Hongbo Zhu explained that the proposed model and experimental investigations provided more insights to provide an experimental guide for high-quality welding of 304SS TWBs for different industrial applications.
Zhu, H., Cheng, B., Ma, G., Lin, X., Zhang, Y., Wu, D., Ning, Y., & Wang, L. (2020). An eave-like model for the welding of 304 stainless-steel tailor-welded blanks with different thicknesses. Optics and Lasers in Engineering, 134, 106309.