In order to investigate the effect of multi-micro laser shock peening on residual stress of copper materials, surface residual stress is measured, and distribution of residual stress under different overlapping rates ...In order to investigate the effect of multi-micro laser shock peening on residual stress of copper materials, surface residual stress is measured, and distribution of residual stress under different overlapping rates and laser energies is explored. Surface mean residual stress is proposed as characteristic means according to the defect of test equipment in existence. Numerical simulation is carried out to display residual stress distribution on top surface and depth in the overlapping process of microseale laser peening. The results show that overlapping rate and laser energy greatly influence the distribution of residual stress, and the surface mean residual stress is an effective characteristic means according to the residual stress distribution along typical paths and mean stress formula.展开更多
Characteristics of microstructures of electroless Ni-P/Ni-W-P duplex coatings were investigated using SEM/EDX and XRD analysis techniques. Microhardness and wear behaviour of the coatings before and after laser crysta...Characteristics of microstructures of electroless Ni-P/Ni-W-P duplex coatings were investigated using SEM/EDX and XRD analysis techniques. Microhardness and wear behaviour of the coatings before and after laser crystallization were evaluated by measurements of hardnesses of coating surface and cross-section, and by unlubricated friction and wear experiments. The results indicate that it is possible to prepare electroless Ni-P/Ni-W-P duplex coatings by sequential immersion in two different plating baths. After laser crystallization, the microstructures of electroless Ni-P/Ni-W-P duplex coatings present the characteristics of higher degree of crystallization and larger grain size for outer layer Ni-W-P than inner Ni-P, but outer layer has a higher hardness. The wear resistance of laser-treated duplex coatings in a given process parameter conditions is superior to the as-plated ones. Laser treatment was performed directly in air without argon protection, which provides the possibility for application of industrialized production.展开更多
文摘In order to investigate the effect of multi-micro laser shock peening on residual stress of copper materials, surface residual stress is measured, and distribution of residual stress under different overlapping rates and laser energies is explored. Surface mean residual stress is proposed as characteristic means according to the defect of test equipment in existence. Numerical simulation is carried out to display residual stress distribution on top surface and depth in the overlapping process of microseale laser peening. The results show that overlapping rate and laser energy greatly influence the distribution of residual stress, and the surface mean residual stress is an effective characteristic means according to the residual stress distribution along typical paths and mean stress formula.
基金Project (ZR2011EMM014) supported by the Natural Science Foundation of Shandong Province, China
文摘Characteristics of microstructures of electroless Ni-P/Ni-W-P duplex coatings were investigated using SEM/EDX and XRD analysis techniques. Microhardness and wear behaviour of the coatings before and after laser crystallization were evaluated by measurements of hardnesses of coating surface and cross-section, and by unlubricated friction and wear experiments. The results indicate that it is possible to prepare electroless Ni-P/Ni-W-P duplex coatings by sequential immersion in two different plating baths. After laser crystallization, the microstructures of electroless Ni-P/Ni-W-P duplex coatings present the characteristics of higher degree of crystallization and larger grain size for outer layer Ni-W-P than inner Ni-P, but outer layer has a higher hardness. The wear resistance of laser-treated duplex coatings in a given process parameter conditions is superior to the as-plated ones. Laser treatment was performed directly in air without argon protection, which provides the possibility for application of industrialized production.
