Effect of surface cleaning on seam quality of laser beam welded mixed joints

In this study, different surface cleaning methods were used to remove greases and oils from the surface of the E235 steel tube component of the diamond segmented drill bit before laser beam welding. The mechanical, chemical and electromechanical cleaning methods were selected because they are suitable for removing greases and oils adhering to the surface during tube production. The cleaned samples were successfully welded using the same heat inputs by laser welding. The effect of mechanical processes with sandblasting and dry-ice blasting, chemical processes with isopropyl alcohol, acetone and alkaline acidic liquid, electromechanical process with a laser beam on micro-computer tomography, break-out value and micro-hardness measurement examined. The cleanliness of the surfaces and strength of the laser-welded joint was inferred from the break-out value (BOV), as this is the principal qualification value in mass production. The results were compared to the untreated sample. According to the results obtained in this study, any defects in the seams were analyzed, and no cracks founded by computer tomography. According to a shade of grey diagram, all the pretreated samples had a higher absorption than the untreated sample. While the chemical methods had a significant effect (59–66 %), the mechanical and electromechanical methods had a positive effect (22–48 %) compared to the untreated sample. In addition, the break-out values showed that the mechanical methods had a significantly higher effect (19 %) than the other surface cleaning methods. This test showed different results from the micro-CT scan. The microhardness test showed no difference between the hardnesses of the cleaned and uncleaned samples and no difference in seam thicknesses. The optimal oil removal process discusses in the conclusion part.