低碳钢激光预熔活性焊接法

Study of laser pre-melting activating welding on low carbon steel

以8 mm厚的低碳钢为研究对象,在氧气的保护下,用小功率光纤激光在待焊焊件表面进行预熔处理,使表面熔化生成一层氧化层,然后用TIG焊或激光电弧复合焊覆盖氧化层,研究工艺参数对焊缝成形的影响.结果表明,激光预熔后进行覆盖焊接,电弧没有收缩,熔深增加到1.5倍左右,表面成形良好.随着电流的增加,熔深增加,但激光预熔后的焊道增加更快.随着焊接速度的增加,熔深减小.随着激光预熔功率的增加,熔深增加.随着复合焊接中激光功率的增加,熔深增加.焊缝含氧量的增加,使得表面张力温度系数由负变正,是低碳钢激光预熔活性焊接熔深增加的主要原因.

The laser pre-melting activating welding of low carbon steel with 8 mm thickness was study. Firstly,the surface of the substrate was pre-melted by the low power laser in oxygen atmosphere to form an oxide layer on the surface. Then TIG welding or laser arc hybrid welding was used to cover the weld.The effect of welding parameters on the weld depth and width was studied. The result shows that the arc was not shrunken during the welding after laser pre-melting. However the penetration increased about 0. 5 times. The weld surface had a good appearance. The penetration increased with the increase of arc current,which had more increase after laser surface pre-melting. The increase of welding speed resulted in a decrease of penetration.The penetration increased with the increase of the pre-melting laser power. Simultaneously,the increase of laser power of hybrid welding also can increase the penetration. The oxygen content of the weld increased when the surface of weld was pre-melted by laser,which leads to the temperature coefficient of surface tension gradient changed from a negative value to a positive value.That is the reason why the penetration can be increased after laser pre-melting.