Both stainless seamless steel pipes and stainless welded steel pipes can be cold processed --- cold rolling and cold drawing to meet higher requirements for cold processed products.
The characteristics of stainless steel pipe cold processing:
1. Improve the surface, improve the corrosion resistance due to the improved surface finish.
2. Further improve the dimensional accuracy of the seamless pipe. After cold rolling or cold drawing with a mandrel, not only the outer diameter accuracy is improved, but also the dimensional accuracy of the wall thickness can be improved.
3. It can produce seamless steel pipes with smaller diameter and thinner pipe wall.
4. Combined with solution heat treatment after cold deformation, the mechanical properties can be improved.
5. Non-standard stainless steel seamless pipes of special sizes and special sections can be produced
Cold working process of stainless steel pipe
1. Cold drawing process:
The diameter of the cold-drawn pipe is heated or the end is necked at room temperature, the surface is pickled to remove scale, and the lubricant is applied for cold drawing. There are three methods of cold drawing. The cold drawing of the plug with the inner diameter of the finished product is called cold drawing of the plug. Cold drawing with a mandrel with the same length as the tube is called mandrel cold drawing or free cold drawing without a mandrel. The inner wall of the cold drawn mandrel is smooth, which can achieve a large deformation ratio, and is suitable for cold drawing of long stainless steel pipes.
The cold drawing machine can be chain type, hydraulic type or hydraulic type. Chain cold drawing can draw two or more steel pipes at a time. In order to reduce the wear between the cold drawn pipe and the die, the quality of the lubricant is very important to improve the efficiency. Usually, the surface scale is removed by pickling, and then coated with lubricant for cold drawing.
The main disadvantages of cold drawn stainless steel pipes are:
The amount of deformation in each pass is small, so there are many processing passes and the production cycle is long; the metal consumption is large. Poor surface finish inside and outside the tube.
2. Cold rolling process:
Cold-rolled stainless steel pipe is a cold working method in which two rolls have progressively smaller roll passes along the circumference, and a mandrel rod with a slope is rolled back and forth, which is called cold Pilger method. A three-roll cold rolling mill can also be used.
The biggest disadvantage of the cold-rolled tube is the hard state, that is, the large yield coefficient, which is not suitable for flaring and bending, so it needs to be thermally solidified (annealed).
The characteristics of stainless steel pipe cold processing:
1. Improve the surface, improve the corrosion resistance due to the improved surface finish.
2. Further improve the dimensional accuracy of the seamless pipe. After cold rolling or cold drawing with a mandrel, not only the outer diameter accuracy is improved, but also the dimensional accuracy of the wall thickness can be improved.
3. It can produce seamless steel pipes with smaller diameter and thinner pipe wall.
4. Combined with solution heat treatment after cold deformation, the mechanical properties can be improved.
5. Non-standard stainless steel seamless pipes of special sizes and special sections can be produced
Cold working process of stainless steel pipe
1. Cold drawing process:
The diameter of the cold-drawn pipe is heated or the end is necked at room temperature, the surface is pickled to remove scale, and the lubricant is applied for cold drawing. There are three methods of cold drawing. The cold drawing of the plug with the inner diameter of the finished product is called cold drawing of the plug. Cold drawing with a mandrel with the same length as the tube is called mandrel cold drawing or free cold drawing without a mandrel. The inner wall of the cold drawn mandrel is smooth, which can achieve a large deformation ratio, and is suitable for cold drawing of long stainless steel pipes.
The cold drawing machine can be chain type, hydraulic type or hydraulic type. Chain cold drawing can draw two or more steel pipes at a time. In order to reduce the wear between the cold drawn pipe and the die, the quality of the lubricant is very important to improve the efficiency. Usually, the surface scale is removed by pickling, and then coated with lubricant for cold drawing.
The main disadvantages of cold drawn stainless steel pipes are:
The amount of deformation in each pass is small, so there are many processing passes and the production cycle is long; the metal consumption is large. Poor surface finish inside and outside the tube.
2. Cold rolling process:
Cold-rolled stainless steel pipe is a cold working method in which two rolls have progressively smaller roll passes along the circumference, and a mandrel rod with a slope is rolled back and forth, which is called cold Pilger method. A three-roll cold rolling mill can also be used.
The biggest disadvantage of the cold-rolled tube is the hard state, that is, the large yield coefficient, which is not suitable for flaring and bending, so it needs to be thermally solidified (annealed).
