How to judge the standards for surface quality of stainless steel strips

One of the criteria for judging the surface quality of stainless steel strips is the uniformity of the oxide scale thickness. This is greatly affected by the quality of the pickling process after heat treatment. In addition, the surface cleaning effect before and after heat treatment also plays a certain role.

The surface finish of the substrate in the thick and thin areas of the stainless steel strip is different, and the dissolution of the surface oxide scale during pickling and the corrosion degree of the substrate at the oxide scale attachment site are different, so the surface of the stainless steel strip is uneven. Therefore, during heat treatment, the oxide scale must be formed evenly. To meet this requirement, there are several conditions to pay attention to.

If oil adheres to the surface of the workpiece during heat treatment, carburization will easily occur. The carburized part of the stainless steel matrix under the oxide scale will be severely corroded. The oil droplets ejected when the heavy oil burner is initially burned will have a great impact if they adhere to the stainless steel workpiece. In addition, the operator's fingerprints attached to the stainless steel workpiece sometimes have an impact, so the operator should not touch the stainless steel workpiece directly with his hands to avoid contaminating the stainless steel workpiece with new oil stains. Wear clean gloves when operating.

It is necessary to fully degrease in trichlorethylene degreasing agent and caustic soda solution, and then use warm water to clean the lubricating oil attached to the cold working surface of the stainless steel workpiece before heat treatment.

In addition, when organic matter or ash adheres to the surface of the stainless steel workpiece, it will also affect the thickness of the oxide scale on the surface of the stainless steel strip during heat treatment.

During heat treatment, the workpiece cannot be in direct contact with the flame port. This is because the thickness of the oxide scale formed on the stainless steel surface where the flame is in direct contact and where there is no contact is also different.

Also pay attention to the parts with remaining oxide scale and the parts without oxide scale before and after heat treatment. If there is residual oxide scale on parts of the treated parts before heat treatment, the thickness and composition of the oxide scale will also be different during further processing, which will cause the surface of the stainless steel strip to be uneven after pickling. Therefore, in addition to paying attention to the final heat treatment, Also pay attention to the surface condition of the stainless steel strip during intermediate heat treatment and pickling.

In addition, the different surface finish of stainless steel belts is also a reason. Because even if heated at the same time, if the surface finish of the stainless steel belt is different, the oxide scale on the relatively rough and fine parts will not be the same. For example, the oxide scale is formed in different places where local defects have been cleaned and where they have not been cleaned, causing uneven appearance of the workpiece after pickling.

Finally, if the atmosphere in the furnace is different, the oxide scale formed will also change. This is also the reason for unevenness after pickling. Because during heat treatment, the atmosphere in all parts of the furnace must be the same, and this requires consideration of the circulation of the atmosphere in the furnace.