If the thickness of the surface oxide scale of the 1060 aluminum plate is not uniform, the surface finish of the base metal under the thick and thin areas is also different, and the dissolution of the surface oxide scale during pickling is different from the corrosion degree of the base metal at the attachment site of the oxide scale by acid, so the surface of the steel plate is not uniform. Therefore, it is necessary to uniformly form oxide scales during heat treatment. To meet this requirement, what issues must be paid attention to?
1. If the 1060 aluminum plate is heated with oil on the surface of the workpiece, the thickness and composition of the oxide scale at the oil-attached part will be different from the thickness and composition of the oxide scale in other parts, and carburization will occur. The carburized part of the base metal under the oxide scale will be severely attacked by the acid. The oil droplets ejected by the heavy oil burner when it first burns will have a great impact if it adheres to the workpiece. It also affects when the operator's fingerprint is attached to the workpiece. Therefore, the operator should not directly touch the stainless steel parts with his hands, and do not make the workpiece stained with new oil. Clean gloves must be worn. If there is lubricating oil attached to the surface of the workpiece during cold working, it must be fully degreased in trichloroethylene degreaser and caustic soda solution, then washed with warm water, and then heat treated.
2. If there are sundries on the surface of the 1060 aluminum plate, especially when organic matter or ash is attached to the workpiece, heating will of course affect the oxide skin.
3. The difference in the atmosphere in the 1060 aluminum plate furnace, the atmosphere in the furnace is different in each part, and the formation of the oxide scale will generally change, which is also the reason for the unevenness after pickling. Therefore, when heating, the atmosphere of each part of the furnace must be the same. For this reason, the circulation of the atmosphere must also be considered. In addition, if the bricks, asbestos, etc., which constitute the bench used for heating the workpiece, contain moisture, the moisture will evaporate during heating, and the atmosphere of the part in direct contact with the water vapor will be different from that of the other parts, and the formation of oxide scale will of course also different. Therefore, objects in direct contact with the heated workpiece must be fully dried before they can be used. However, if it is placed at room temperature after drying, the moisture will still condense on the surface of the workpiece under the condition of high humidity. Therefore, it is best to dry before use.
4. If the part of the 1060 aluminum plate has residual oxide scale before heat treatment, and there is residual oxide scale and no scale after heating, there will be differences in the thickness and composition of the oxide scale, causing uneven surface after pickling, so pay attention not only to the final heat treatment, but also to the intermediate heat treatment and pickling.
5. There is a difference in the oxide scale produced on the surface of the aluminum plate directly contacted by the flame of gas or oil and where it is not in contact. Therefore, it is necessary to prevent the treatment member from directly contacting the flame port during heating.