摘要
研究了Ｎｄ∶ＹＡＧ脉冲激光离散加工时功率密度和作用时间对熔池几何形态的影响。５ＣｒＭｎＭｏ钢的实验结果表明：在一定加工条件下，熔池存在热传导型和深熔型两种形态。激光作用时间小于４ｍｓ时，随着激光功率密度的增加，熔池深宽比显著增加；作用时间超过４ｍｓ后，功率密度对深宽比的影响减弱。基于线性热传导模型的计算结果表明：熔凝起始阶段固态加热过程可忽略；熔池几何尺寸在激光脉冲结束后某个时刻达到最大值；当平均功率密度大于５×１０５Ｗ／ｃｍ２，同时激光作用时间大于２ｍｓ时。
Geometrical characteristics of melted pools were studied as for NdYAG pulse laser spot remelting. The experimental results showed the depth/width radio of pool increased significantly with the power intensity; when the pulse time surpassed 4ms, the influence of power intensity on the depth/width radio became weak. Based upon the liner heat conduction model, the calculated results of the steel showed that the solide heating processing at the initial stage could be omitted, and heat conduction\|type pool would be transformed to deep pool when critical power intensity and critical pulse time surpassed 510\+5W/cm\+2 and 2ms respectively. The theoretical prediction was well consistent with experimental results.
基金
国家自然科学基金
中国科学院重点资助
关键词
脉冲激光熔凝
几何形态
熔池
激光加工
pulse laser remelting,\ geometrical characteristics of melted pool,\=heat conduction,\ thermophysical parameter
