1. Improved Overall Mechanical Properties
Strength and Toughness Balance: After heat treatment, the tensile strength of seamless steel tubes can reach over 1176MPa (such as V-150 steel grade), while maintaining an elongation of ≥12% and impact energy of ≥40J, achieving the optimal combination of high strength and high toughness.
Microstructure Optimization: Formation of uniform tempered sorbite (spherical carbide dispersion), compared to normalized sorbite (lamellar structure), significantly improves yield strength and fatigue strength.
2. Improved Microstructure
Grain Refinement: After high-temperature tempering of quenched martensite, the grain size is controlled to ASTM grade 8 or higher, reducing brittleness.
Residual Stress Elimination: Tempering at 500-650℃ eliminates internal stresses from quenching, reducing the risk of deformation and cracking.
3. Application Performance Adaptation
Dynamic Load Adaptability: Heat-treated steel pipes perform excellently under alternating stress (such as in oil drilling tools and shaft parts), increasing fatigue life by 2-3 times.
Surface Hardening Potential: After heat treatment, wear resistance can be further improved through surface hardening (such as induction heating), meeting the needs of high-friction working conditions.
4. Limitations
Increased Cost: The heat treatment process is energy-intensive and is suitable for applications with stringent performance requirements (such as deep-sea oil and gas casing).
Hardness Limitation: The surface hardness of the heat-treated state is relatively low (HRC25-30), requiring additional treatment to improve wear resistance.
