Why Does The Seamless Pipe Produce Chromatic Aberration?

Changsha China
Categories: Building Engineering / China Tags:
cs seamless pipe
seamless steel pipe

CS seamless pipe is a kind of long steel with a hollow section and no joints around it. It is used to manufacture superheated steam pipes, boiling water pipes and locomotive boilers of various structures for low and medium pressure boilers. and high-quality carbon structural steel for arch brick pipes. However, there will be some chromatic aberration in use. Let's analyze the reasons for the chromatic aberration:

(1) The reason for the color difference of seamless steel pipe is mainly due to the violent reaction of iron and zinc. The violent reaction of Fe-Zn makes the complete coating composed of the alloy layer and the pure zinc layer become the phenomenon of only the alloy layer without the pure zinc layer; gray or dark gray is the color of the iron-zinc alloy. In addition, if the quality of the zinc liquid deteriorates, the iron content in the zinc liquid will increase, and the pure zinc layer on the surface after galvanizing will appear gray due to iron content, resulting in color difference.

(2) The plating material contains more carbon, silicon, sulfur, phosphorus and other elements. The electrochemical reaction between iron and zinc is due to the inert electricity formed by these elements, and the relative potential becomes higher, which leads to the intensification of the iron and zinc reaction; the content of metal elements such as aluminum in the zinc liquid is relatively small, and for galvanizing of seamless steel pipes and other materials, The iron-zinc reaction cannot be effectively inhibited; the iron content in the zinc solution increases, which deteriorates the quality of the zinc solution.

(3) When the seamless steel pipe is heat treated, the holding time should ensure that the steel pipe in the furnace can be completely burned through, so that the temperature is uniform, and the due structure transformation is completed, so as to obtain uniform structure and performance. Generally, increasing the heating temperature can appropriately shorten the holding time. During low temperature annealing (including softening, stress relief and recrystallization annealing), the closer the annealing temperature is to the lower critical point A1, the faster the recovery of the seamless steel pipe and the more complete the effect of eliminating work hardening. Therefore, the holding time can also be appropriate. shorten.

(4) The temperature of the upper and lower surfaces is uneven: the cs seamless pipe is very straight after being cut in production, but it bends when it is cooled on the finishing bench, and the overall bending direction of the steel pipe is the same. Solution: Renovate the water-cooling device to make the amount of cooling water on the upper surface controllable, and keep the temperature of the upper and lower surfaces of the steel pipe the same; for large-diameter steel pipes, when the amount of water-cooled cooling water is increased to a large extent, the temperature of the upper surface is still higher than that of the lower surface, which can be appropriately reduced Speed ​​up the production line, or install a cooling liquid water tower to speed up the cooling of the cooling liquid; adopt the reverse adjustment method, that is, according to the direction and degree of bending of the steel pipe on the finishing bench, reverse adjustment during sizing and straightening.