1. Material Definition and Core Properties
Q: What is ASTM A519 5115 steel pipe?
A:
5115 steel pipe is a medium-carbon chromium alloy steel seamless pipe (UNS G51150) specified in the ASTM A519 standard. Its core composition is 0.13%-0.18% carbon and 0.70%-0.90% chromium. This material achieves a balance of high strength (tensile strength ≥700 MPa) and good wear resistance through solid solution strengthening and carbide-forming properties of chromium. It features moderate hardenability (oil quenching critical diameter 40-60 mm) and a grain size of ASTM grades 7-9 after heat treatment, making it particularly suitable for medium-load shafts and gear components.
2. Mechanical Properties and Technical Parameters
Q: What are the performance specifications of 5115 steel pipe? A:
In the quenched and tempered state (850°C oil quenching + 550°C tempering):
Strength properties: Tensile strength 700-850 MPa, yield strength 500-650 MPa
Toughness: Elongation ≥ 18%, reduction of area ≥ 50%, room temperature impact energy ≥ 40J
Special properties: Contact fatigue limit (10⁷ cycles) ≥ 1200 MPa, weld carbon equivalent CE ≤ 0.40
3. Typical Applications
Q: What are the main applications of 5115 steel pipe?
A:
Automotive industry: Transmission gears, drive shafts (requires surface hardening to HRC 55-60)
Mechanical manufacturing: Hydraulic cylinders, machine tool spindles (medium speed operating conditions)
General engineering: Agricultural machinery connecting rods, conveyor roller shafts
4. Key points for heat treatment and processing
Q: How to optimize the heat treatment and processing of 5115 steel pipe? A:
Recommended Process:
Surface induction hardening (frequency 10-50kHz) to obtain a 2-5mm hardened layer.
Welding: Use ER70S-6 welding wire, preheated to 150-200°C.
Turning: Use TiCN-coated tools (cutting speed 80-100 m/min).
Critical Control: Avoid prolonged exposure to the temper brittleness zone at 300-500°C.
5. Comparison with Similar Materials
Q: What is the difference between 5115, 5120, and 4115 steel pipe?
A:
vs. 5120: 5115 has a lower carbon content (0.13%-0.18% vs. 0.17%-0.22%), resulting in better weldability but 10% lower strength.
vs. 4115: 5115 does not contain molybdenum, resulting in a 15% lower cost but slightly lower high-temperature strength (>300°C).
