Surface cleaning requirements before welding
Manual arc welding: Manual arc welding (SMAW) has relatively low requirements for the surface cleanliness of the base metal. It can tolerate thin layers of rust, paint, or dirt to a certain extent, but there will be more spatter. However, in order to ensure the quality of the weld seam, it is still recommended to clean the surface of S355J0WP steel and the groove surface of the weld joint to remove oil stains, rust, and other impurities.
Gas - shielded welding: Gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) have higher requirements for surface cleanliness. Before welding, the surface of S355J0WP steel must be thoroughly cleaned to remove all kinds of dirt, rust, oxide scale, etc., otherwise, it is easy to produce defects such as porosity and cracks in the weld seam.
Interlayer pollution prevention during welding
Manual arc welding: During the welding process, attention should be paid to controlling the welding current and arc length to avoid excessive spatter splashing onto the surface of the weld seam and causing pollution. If multi - layer welding is carried out, the slag between layers needs to be cleaned up in time to prevent interlayer pollution.
Gas - shielded welding: Gas - shielded welding has better arc stability and less spatter, but in the case of multi - layer welding, it is also necessary to clean the surface of the previous layer of weld metal to remove oxides and other impurities to ensure the quality of the subsequent weld layer.
Weld seam treatment requirements after welding
Manual arc welding: After manual arc welding, the surface of the weld seam usually has more slag and spatter, which need to be cleaned up by mechanical methods such as grinding wheels and wire brushes. If the corrosion resistance of the weld seam area needs to be improved, appropriate surface treatment such as spraying a rust - proof paint can be carried out.
Gas - shielded welding: The surface of the weld seam after gas - shielded welding is relatively clean, but there may still be some oxides and other impurities. Mechanical cleaning or chemical cleaning methods can be used for treatment. At the same time, in order to ensure the overall corrosion resistance of S355J0WP steel, the weld seam area can be subjected to post - weld heat treatment to eliminate welding residual stress and improve the performance of the weld seam area.
