自振脉冲空化射流对6061铝合金表面强化规律

Rule of Surface Strengthening of 6061 Aluminum Alloy by Self-excited Oscillation Pulsed Cavitation Water Jet Peening

为了提高6061铝合金材料表面硬度、强度和耐磨性等机械性能,通过振脉冲空化射流束冲击6061铝材料表面。测量和分析未处理表面和15、20、25 MPa三种工作压力下射流束冲击试样1、2、3、4、5 min后材料表面微观组织形貌、试样表面轮廓、粗糙度Ra值、Rz值和表面硬度层等因素的变化,定性及定量研究自振脉冲空化射流技术对材料表面机械性能的影响规律。结果表明,与未处理表面相比,15 MPa时射流束未对材料表面造成严重塑性变形,其表面只存在极少不均微坑,Ra值增加0. 25,硬度增加15%,强化效果不明显; 20 MPa时射流束对材料表面产生严重塑性变形,能够明显观测到表面存在密集且均匀的凹坑分布,Ra值增加1. 2,硬度增加78. 3%,强化效果较好; 25 MPa时射流束对材料表面产生过度塑性变形,Ra值增加7. 5,硬度增加81. 3%,材料表层发生剥蚀现象,影响到材料的使用性能。可见,在工作压力20 MPa,冲击时间3 min,靶距20 mm时自振脉冲空化射流技术对材料表面强化效果最好,材料机械性能提高近2倍且表面改性极小。此技术对提升材料表面耐磨性及硬度强化效果起到极为显著作用。

In order to improve the mechanical properties of6061aluminum alloy,such as surface hardness,strength and wear resistance,the surface of6061aluminum material was pounded by selfexcited oscillating pulsed cavitation waterjet.Analyzed the differences of microstructure,profile,roughness and hardness of surfaces between the untreated material and other test samples impacted by waterjet,the influence of the self-excited oscillation pules cavitation waterjet technology on the mechanical properties of the surface of the material was qualitatively and quantitatively studied,under three working pressures of15,20,and25MPa impact specimens at1,2,3,4and5min.Compared with the untreated surface,the jet beam did not cause serious plastic deformation on the surface of the material at15MPa,and its surface only had few nonuniform micro pits.The Ra value increased by0.25,the hardness increased by15%,and the strengthening effect was not obvious.Severe plastic deformation of material surface impacted by jet beam at20MPa,and can clearly observe the dense and uniform pit distribution on the surface.The value increases by1.2,the hardness HV increases by78.3%,and the strengthening effect is excellent.The jet beam causes excessive plastic deformation on the material surface when25MPa.The Ra value increased by7.5,the hardness HV increased by81.3%,and the surface of the material was denuded,which greatly affected the using performance of the material.Self-excited oscillating pulsed cavitation waterjet peening technology plays an important role in improving the surface abrasion resistance and hardness of materials.With the working pressure of20MPa,the impact time of3min,and the target distance of20mm,the material surface strengthening and its other mechanical properties have been improved significantly.