CFRP plates are important advanced material used in the aerospace field, high-quality and high-efficiency drilling is the main application processing demand of CFRP. In this paper, a 532 nm nanosecond fiber laser with adjustable pulse duration is used and the scanning path was planned as Z-direction up-bottom incremental cutting, and X-Y direction concentric circle cutting scanning mode to realize the CFRP plates hole drilling, and obtain high drilling performance. The mechanisms of material removal for CFRP plates hole drilling under 532 nm nanosecond laser is explored, and it is mainly attributed to thermal evaporation accompanied by certain heating carbonization. The results show that a narrow width of HAZ can be obtained with short pulse duration, the minimum value of HAZ width at hole entrance edge is 18.74 µm, and the matrix material damage near the HAZ becomes small. Reducing the pulse duration also helps to decrease the drilling taper (minimum taper value 0.046), the taper of the drilling hole is smaller than that of the drilling dicing. But the drilling efficiency is reduced due to the low pulse energy with short pulse duration.

Fiber laser welding of dissimilar materials between AISI316L austenitic stainless steel and EH36 ship steels were conducted. Then the effects of welding speed on microstructure and mechanical characterization of the welded joint were investigated. Optical microscopy, Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) were used to analyze the microstructure. Microhardness testing, transverse tensile strength, and impact tests at the temperature of −40 °C were performed to study the mechanical properties. The martensite phase formed due to the rapid cooling rate during laser welding and low Cr_eq/Ni_eq ratio. The coarse martensite grains in the center seam are transformed to finer martensite grains as the welding speed increases resulting in the higher cooling rate. The microhardness of joints was about 350 HV_0.3, which was twice that of the base metal because of the formation of the martensite phase. When the welding speed was 0.6 m/min, fewer defects were found, and tensile testing indicated overmatching of the weld metal relative to the base metal. In addition, the joints also exhibited better ductility and impact toughness.