Precision Seamless Alloy Steel Pipe

• ​Introduction

Precision alloy steel tubing refers to high-performance steel tubes manufactured with strict dimensional tolerances, superior surface finish, and enhanced mechanical properties.Widely used in numerous fields such as machining, machinery manufacturing, automotive industry, aerospace, hydraulic equipment， and Precision Machinery and Instruments.

• ​Main Functions

High-strength load bearing：Used in high-pressure hydraulic systems and mechanical transmission parts to withstand complex stress and dynamic loads.​ High-precision fitting: Due to its high-precision dimensions, it can achieve a tight fit with other precision parts, ensuring the stable operation and precise transmission of mechanical systems. It is widely used in precision machinery and equipment. Fatigue and wear resistance：Alloy treatment enhances the material’s fatigue limit, suitable for high-cycle stress conditions (e.g., engine connecting rods, crankshafts).​ Lightweight design：Optimized alloy composition and processing techniques reduce weight while maintaining strength, supporting lightweight applications in aerospace and automotive industries.

• ​Tubing Standards

ASTM A519；EN 10305-1；GB/T 3639​

• ​Material & Performance

4130，4140，5140；34CrMo4，42CrMo4，42Cr4；30CrMo，42CrMo，40Cr；

High Strength and High Toughness: Withstand high pressure, high temperature, and mechanical stress. High Precision: Ensure strict tolerance requirements for critical applications. High Fatigue Resistance: Suitable for high-frequency vibration conditions. Machinability Adaptability: Excellent cold and hot working properties, facilitating the manufacturing of complex-shaped components.

• ​Manufacturing Process

1.Raw Material Preparation， Select high-purity alloy round steel billets to ensure chemical compositions comply with standards.

2.Hot Piercing， Heat the billet to the set temperature, and pierce it into a hollow mandrel pipe through a piercing machine to form the prototype of the steel pipe.

3.Rolling， Hot Rolling: After heating, the mandrel pipe is further reduced in diameter and wall thickness via hot rolling mills (such as continuous rolling mills or sizing machines) to improve dimensional accuracy. Cold Rolling/Cold Drawing: Cold roll or cold draw the hot-rolled pipe. Through multiple passes of rolling, the dimensional accuracy and surface finish of the steel pipe meet precise requirements.

4.Heat Treatment， Perform annealing, quenching + tempering, or solution treatment based on the alloy composition and application requirements. The heat treatment process must strictly control temperature, holding time, and cooling rate to ensure stable pipe performance.

5.Straightening & Cutting， Adjust the straightness using a roller-type straightening machine, then cut to the specified length as required.

6.Surface Treatment， Adopt processes such as pickling, phosphating, or electroplating to remove scale and improve surface corrosion resistance.

7.Inspection， Dimensional Inspection: Measure outer diameter, wall thickness, length, etc., to ensure compliance with tolerance standards. Non-Destructive Testing (NDT): Detect internal and surface defects via Ultrasonic Testing (UT), Eddy Current Testing (ET), or Magnetic Particle Testing (MT). Mechanical Property Testing: Conduct tensile, impact, and hardness tests to verify indicators such as strength and toughness. Metallographic Analysis: Inspect the microstructure to ensure grain size and precipitates meet requirements.

• Specifications