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从力学的角度和能量的角度解释机械振动对焊接熔池金属凝固过程影响的机理。通过分析机械振动对焊接熔池金属的宏观作用和微观机理后认为 :机械振动改变了熔池中的结构起伏分布和能量起伏分布的状态 ,使晶体形核更为容易 ;机械振动使柱状树枝晶的枝晶折断 ,减小了成分过冷区的大小 ,抑制了柱状树枝晶的长大 ,被打碎的枝晶在熔池中独立长大成为等轴晶 ,等轴晶的数量增多 ;机械振动使熔池液体对流速度加快 ,紊流层宽度增大 ,焊缝的宏观偏析减弱 ,气孔和夹渣等缺陷减少。机械振动对焊接熔池凝固的这些影响对机械振动焊接焊缝组织和性能的改善起了重要的作用
The mechanism of mechanical vibration affecting the metal solidification process of weld pool is explained from the view of mechanics and energy. By analyzing the macroscopic effect and microscopic mechanism of mechanical vibration on weld pool metal, it is considered that the mechanical vibration changes the distribution of the structure in the weld pool and the state of energy fluctuation distribution, making the crystal nucleation easier. The mechanical vibration makes the columnar dendrite Of the dendrites, reducing the size of the undercooling region, inhibiting the growth of columnar dendrites, broken dendrite independent growth in the pool to become equiaxed, the number of equiaxed grains increased; mechanical Vibration makes the liquid convection speed of molten pool accelerate, the width of turbulence layer increases, the macro segregation of weld decreases, and the porosity and slag inclusions decrease. These effects of mechanical vibration on the weld pool solidification play an important role in improving the microstructure and properties of the mechanical vibration welding weld