High-precision small-diameter high-pressure boiler seamless steel tubes have been widely used in hydraulic systems and diesel fuel systems. At present, cold-rolled or cold-drawn capillaries are generally used to manufacture high-precision, small-diameter, high-pressure seamless steel pipes. Although they can meet the technical requirements, there are still the following problems: although the cold-drawn process has high production efficiency, it will inevitably make The internal defects of the material are expanded and the structure is loose. Compared with the cold rolling process, the compressive capacity and the quality of the inner and outer surfaces of the steel pipes made by the steel pipe are relatively low; while the cold rolling process can increase the density of the material, the surface quality is good, and the quality of the inner and outer surfaces is relatively low. The dimensional accuracy is high, but there is a problem of low production efficiency. Especially for small-diameter steel pipes, 2 to 3 passes of cold rolling are required to meet the required technical requirements, and it is difficult to meet the needs of efficient production. To this end, the author proposes a process with high production efficiency, good quality and high dimensional accuracy, which is suitable for the manufacture of small-diameter high-pressure seamless steel pipes, and has achieved good application results.

Production Technology of High Precision Small Diameter High Pressure Boiler Seamless Steel Tube

The specific operation steps of high-precision small-diameter high-pressure boiler seamless steel pipe are as follows:

(1) Pickling, phosphating and saponifying the capillary with a diameter of 15 mm to 30 mm.
(2) One pass of cold rolling is performed on the pretreated steel pipe.
(3) Perform oxygen-free bright annealing on the steel pipe after one pass of cold rolling.
(4) Pickling, phosphating and saponifying the steel pipe after oxygen-free bright annealing treatment again.
(5) The steel pipe that has undergone oxygen-free bright annealing and pretreatment is subjected to shrinking processing before cold drawing.
(6) Perform 1 to 3 continuous cold drawing on the steel pipe after shrinkage processing. The number of cold drawing passes is determined according to the allowable diameter reduction of the material, and whether to use a cold drawn short mandrel is determined according to the size of the pipe diameter. .
(7) Perform oxygen-free bright normalizing or stress relief annealing on the cold drawn seamless steel pipe.
(8) Straighten and truncate the steel pipe after heat treatment.
(9) Carry out non-destructive testing on the straightened and truncated steel pipes.

(10) Galvanizing, military green passivation or blackening treatment of steel pipes confirmed to be defect-free by flaw detection.

Advantages of high-precision small-diameter high-pressure boiler tubes:

The organic combination of the cold rolling process and the cold drawing process not only gives full play to the advantages that the cold rolling process can increase the density of the material, the surface quality is good, and the dimensional accuracy is high, but also maintains the advantages of the high production efficiency of the cold drawing process; especially It has significant economic and social benefits for the manufacture of high-precision small-diameter high-pressure boiler seamless steel tubes.