DIN2391
Date:2026-08-25View:3Tags:Stainless steel pipe,ERW steel pipe,Sprial steel pipe
DIN 2391 is a globally recognized technical standard for precision seamless steel tubes, established by the German Association for Standardization (DIN). Its widespread application in industries such as automotive manufacturing and hydraulic systems stems from its extremely high requirements for the dimensional accuracy, surface quality, and mechanical properties of the steel tubes. Under this standard, steel tubes are typically manufactured using cold drawing or cold rolling processes, meeting the demands of high-pressure and high-reliability applications.
Core Application Areas
Due to its superior performance, DIN 2391 steel tubes are primarily used in fields requiring extremely high precision and reliability:
1. Hydraulic and Pneumatic Systems: This is one of its main application scenarios, often used as rigid tubing in hydraulic systems to transmit high-pressure hydraulic fluid.
2. Automotive Manufacturing: Used in the manufacture of critical components such as brake hydraulic lines, power steering lines, seat frame support tubes, and shock absorber cylinders.
3. Mechanical Engineering and Precision Equipment: Widely used in hydraulic pipelines of various engineering machinery, injection molding machines, diesel engines, etc.
DIN 2391 standard mainly covers three core grades, each corresponding to different European standard codes and application scenarios:
St35 (corresponding to European standard E235): This is the basic grade in this standard, possessing good comprehensive mechanical properties and machinability, and is one of the most widely used carbon steel pipe grades.
St45 (corresponding to European standard E255): This grade has a certain degree of strength improvement compared to St35, suitable for applications requiring higher working pressure.
St52 (corresponding to European standard E355): This is a high-strength alloy steel grade, often used in components with extremely stringent requirements for structural strength and fatigue resistance, such as high-pressure hydraulic cylinders or load-bearing structural components in automotive chassis.
Textual Description of Delivery Conditions in DIN 2391: In the DIN 2391 standard, the "delivery condition" of steel pipes is a key parameter in material selection, directly determining the material's mechanical properties and subsequent processing methods. Common delivery conditions include:
BK (Cold-drawn/Hard State): This refers to steel pipes that have undergone cold working and are not subjected to further heat treatment. In this state, the steel pipe has the highest strength but the worst plasticity, making it unsuitable for subsequent processing involving large deformations such as cold bending and flaring.
BKW (Cold-drawn/Soft State): The steel pipe undergoes a slight cold drawing after final heat treatment. Its strength and plasticity are between BK and BKS, allowing for a certain degree of cold deformation processing.
BKS (Stress-Relief Annealed): The steel pipe has undergone stress-relief annealing after cold working. In this state, the steel pipe possesses good plasticity and dimensional stability, allowing for appropriate further processing.
GBK (Annealed): The steel pipe undergoes annealing in a protective atmosphere. In this state, the steel pipe has good plasticity and toughness, but relatively low strength.
NBK (Normalized): The steel pipe undergoes normalizing heat treatment in a protective atmosphere to obtain a uniform and refined grain structure. This is a very important and widely used condition for DIN 2391 steel pipes. It ensures that the inner and outer walls of the steel pipe are free of oxide layers (presenting a bright surface), while also possessing good comprehensive mechanical properties. Therefore, it is very popular in automobile manufacturing and hydraulic systems.
