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利用输出波长为1064 nm、脉冲宽度为20 ns的钕玻璃YAG激光器,对2A02铝合金进行了表面冲击强化试验。测定了激光冲击后材料的表面硬度和残余应力,用快速傅里叶逆变换(IFFT)方法分析了铝合金激光冲击诱导的晶内亚结构及其演变行为。结果表明,激光冲击强化可使2A02铝合金表面硬度提高50%以上,残余压应力达到120 MPa以上。微观组织的透射电镜(TEM)及IFFT分析结果表明,激光冲击区域晶内位错组态丰富,由刃位错和中心位错带等组成;位错墙可细化晶粒;位错偶极子聚集成为激光冲击非平衡形变条件下纳米晶内亚结构特征构元。激光冲击诱发的晶格内复杂的位错组态和晶格畸变是表面硬度和残余应力提高的主因。
2A02 aluminum alloy was subjected to the surface impact enhancement test by using a neodymium glass YAG laser with a wavelength of 1064 nm and a pulse width of 20 ns. The surface hardness and residual stress of the material after laser shock were measured. The in-plane laser induced sub-structure and its evolution behavior were analyzed by the inverse fast Fourier transform (IFFT) method. The results show that laser shock strengthening can improve the surface hardness of 2A02 aluminum alloy by more than 50% and the residual compressive stress of 120 MPa. Transmission electron microscopy (TEM) and IFFT analysis of the microstructure showed that the crystal dislocation in the laser shock zone is rich in dislocation configuration, which consists of edge dislocation and center dislocation band, dislocation wall can refine the grain, dislocation dipole The sub-aggregates become the characteristic structural sub-structure of nanocrystals under laser shock and unbalanced deformation. The complex dislocation configuration and lattice distortion in the lattice induced by laser shock are the main reasons for the increase of surface hardness and residual stress.