Stainless steel seamless pipes are widely used in high-pressure, low-temperature and corrosion-resistant environment piping systems. Mechanical properties, process properties and corrosion resistance are three important indicators to measure the quality of steel pipes, and are also important guarantees for safe navigation of ships. So how to avoid surface quality problems?
1. Control the quality of raw materials
The raw materials used in the production of seamless steel pipes are mainly continuous casting round tube billets and rolled (forged) round steel. Ensuring the quality of steel billets is the first step to ensure the quality of steel pipes, mainly including steelmaking level, pouring and cooling process, and forming quality. The first is to improve the level of steelmaking. It is necessary to reduce harmful elements and gases (nitrogen, hydrogen and oxygen), improve the uniformity and purity of components, reduce non-metallic inclusions, and change their distribution forms. When the composition of the billet is uneven and severe segregation occurs, the rolled steel pipe will show a serious band structure, thereby reducing the mechanical properties and corrosion properties of the steel pipe, or even unqualified. Non-metallic inclusions (such as sulfides and oxides, silicates) are pressed into thin sheets, which will not only affect the performance of the steel pipe, but may also cause cracks in the steel pipe during the production process. In addition, the shape deviation of the billet, such as straightness, diameter and ovality, will directly affect the quality of the perforation, resulting in quality defects of the waste tube.
2. Ensure the accuracy and uniformity of the furnace temperature control
The furnaces used in the manufacture of seamless steel pipes include billet heating furnaces and steel pipe heat treatment furnaces. Temperature control accuracy and uniformity are two important indicators for judging the quality of heating equipment and an important guarantee for heating process. Therefore, manufacturers should strictly implement the regulations on thermocouple service life and calibration cycle, as well as furnace temperature uniformity detection.
The formulation of the heating process should comprehensively consider the inherent properties of the furnace equipment, the type and quantity of the tube blank or steel pipe, and strictly control the heating rate, holding time and cooling rate to avoid cracks, overheating or overburning.
3. Optimize inspection process and equipment
The inspection of intermediate products in the process of stainless steel seamless steel pipe making is the key to controlling the quality of finished pipes, especially the quality of the inner wall surface, which must be grasped from the source. First of all, it is necessary to establish reasonable and effective inspection and processing procedures to ensure that existing problems can be found and can be effectively dealt with. Secondly, adequate and effective testing equipment is also required. Such as endoscopes, thickness gauges, flashlights, etc., can quickly identify the type and location of defects.
Stainless steel round steel billets are made into seamless steel pipes through the main processes of piercing, cold drawing/cold rolling, solid solution, straightening, and pickling. The various pipe-making links complement each other, especially the quality control of raw materials and intermediate products, which is an important guarantee to ensure that the chemical composition, surface quality, mechanical properties, process performance and corrosion resistance of the finished pipe meet the specifications and standards.
1. Control the quality of raw materials
The raw materials used in the production of seamless steel pipes are mainly continuous casting round tube billets and rolled (forged) round steel. Ensuring the quality of steel billets is the first step to ensure the quality of steel pipes, mainly including steelmaking level, pouring and cooling process, and forming quality. The first is to improve the level of steelmaking. It is necessary to reduce harmful elements and gases (nitrogen, hydrogen and oxygen), improve the uniformity and purity of components, reduce non-metallic inclusions, and change their distribution forms. When the composition of the billet is uneven and severe segregation occurs, the rolled steel pipe will show a serious band structure, thereby reducing the mechanical properties and corrosion properties of the steel pipe, or even unqualified. Non-metallic inclusions (such as sulfides and oxides, silicates) are pressed into thin sheets, which will not only affect the performance of the steel pipe, but may also cause cracks in the steel pipe during the production process. In addition, the shape deviation of the billet, such as straightness, diameter and ovality, will directly affect the quality of the perforation, resulting in quality defects of the waste tube.
2. Ensure the accuracy and uniformity of the furnace temperature control
The furnaces used in the manufacture of seamless steel pipes include billet heating furnaces and steel pipe heat treatment furnaces. Temperature control accuracy and uniformity are two important indicators for judging the quality of heating equipment and an important guarantee for heating process. Therefore, manufacturers should strictly implement the regulations on thermocouple service life and calibration cycle, as well as furnace temperature uniformity detection.
The formulation of the heating process should comprehensively consider the inherent properties of the furnace equipment, the type and quantity of the tube blank or steel pipe, and strictly control the heating rate, holding time and cooling rate to avoid cracks, overheating or overburning.
3. Optimize inspection process and equipment
The inspection of intermediate products in the process of stainless steel seamless steel pipe making is the key to controlling the quality of finished pipes, especially the quality of the inner wall surface, which must be grasped from the source. First of all, it is necessary to establish reasonable and effective inspection and processing procedures to ensure that existing problems can be found and can be effectively dealt with. Secondly, adequate and effective testing equipment is also required. Such as endoscopes, thickness gauges, flashlights, etc., can quickly identify the type and location of defects.
Stainless steel round steel billets are made into seamless steel pipes through the main processes of piercing, cold drawing/cold rolling, solid solution, straightening, and pickling. The various pipe-making links complement each other, especially the quality control of raw materials and intermediate products, which is an important guarantee to ensure that the chemical composition, surface quality, mechanical properties, process performance and corrosion resistance of the finished pipe meet the specifications and standards.
