The quality of the surface of the stainless steel tube is mainly determined by the pickling process after the heat treatment. However, if the surface heat treatment is formed on the surface of the heat treatment, the surface roughness and uniformity can not be improved by acid pickling. So should pay full attention to heat treatment before heating or heat treatment surface cleaning. …
The quality of the surface of the stainless steel tube is mainly determined by the pickling process after the heat treatment. However, if the surface heat treatment is formed on the surface of the heat treatment, the surface roughness and uniformity can not be improved by acid pickling. So should pay full attention to heat treatment before heating or heat treatment surface cleaning.
If the thickness of the surface of the stainless steel tube plate is not uniform, the thickness of the surface of the base metal below the thick and thin place is also different, and the surface oxide of the surface oxide is dissolved and oxidized by the oxidized skin The degree of different, so the steel surface is not uniform. Therefore, when the heat treatment is heated, it is necessary to uniformly form the scale. To meet this requirement, attention should be paid to the following conditions.
(1) If the surface of the workpiece is attached with oil, the thickness of the scale of the oil adhering site and the thickness and composition of the other parts are different and carburizing. The carburized part of the base metal will be severely attacked by acid. Heavy oil burner when the initial combustion of oil droplets, if attached to the workpiece, the impact is also great. The operation of the fingerprints attached to the workpiece will also be affected. Therefore, the bath for the major members do not touch the stainless steel pipe directly, do not make the workpiece stained with new oil. Must wear clean gloves.
If the surface of the workpiece if the cold processing of lubricating oil, etc., must be in the trichlorethylene degreasing agent, caustic soda solution in the full degreasing and then rinse with warm water, and then heat treatment.
(2) If the surface of the workpiece there are debris, to be other organic or gray attached to the workpiece, the heating of course, will have an impact on the scale.
(3) Oxygen or oil flames Direct contact with the surface of the stainless steel pipe and the place where there is no difference in the scale of the scale. Therefore, it is necessary to make the treatment member not directly in contact with the flame port during heating.
(4) If the local part of the treatment part before the heat treatment of residual scale, after heating the remaining parts of the scale and the site of no scale, there will be the thickness of the scale and composition of the difference, causing pickling after the surface is not Evenly, so not only pay attention to the final heat treatment, but also pay full attention to the middle heat treatment and pickling.
(5) the effect of different surface finish
If the surface finish is different, even if the same heating, the surface roughness and fine oxide scale is not the same. For example, where the local defects are cleaned and where they are not cleaned, the conditions of the formation of the scale are different, so that the surface of the workpiece is not uniform after pickling.
(6) the difference between the furnace atmosphere
Furnace atmosphere in the local differences, the formation of a scale will change, which is caused by acidity after the reasons for uneven. Therefore, in the heating, the furnace parts of the atmosphere must be the same. To this end, we must also consider the cycle of the atmosphere.
In addition, it is necessary to evaporate the moisture, and the parts of the direct contact with the water vapor are different from those of the other parts, and the formation of the scale is, of course, It is different. Therefore, objects that are in direct contact with the heated workpiece must be fully dried to use. However, after drying, such as placed at room temperature, in the case of high humidity, the water will still condense on the surface of the workpiece. So, it is best to dry before use.
Source: China Steel Tube Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)