Stainless pipe fitting,stainless fitting,duplex stainless,31803,32750,32760,we are one of largest sour service stainless fitting supplier according to ISO 10156.
1.Product Description
BG-42 (UNS S42700) is a premium vacuum arc remelted martensitic stainless bearing steel manufactured via VIM+VAR dual vacuum refining process. The optimized combination of chromium, molybdenum and vanadium endows the grade with excellent hot hardness comparable to M50 high-speed bearing steel and decent anti-corrosion property superior to conventional 440 series stainless steel. This alloy is engineered for critical components working under high load, elevated temperature and mild corrosive surroundings, widely adopted in aerospace, petrochemical, precision machinery and medical equipment industries.
2.BG-42 Chemical Composition (Weight %, Standard Specification)
| Element | Content |
| Chromium (Cr) | 13.80 ~ 14.70 |
| Molybdenum (Mo) | 3.80 ~ 4.20 |
| Vanadium (V) | 1.12 ~ 1.28 |
| Carbon (C) | 1.08 ~ 1.12 |
| Manganese (Mn) | 0.28 ~ 0.48 |
| Silicon (Si) | 0.22 ~ 0.38 |
| Nickel (Ni) | ≤ 0.38 |
| Copper (Cu) | ≤ 0.32 |
| Phosphorus (P) | ≤ 0.012 |
| Sulfur (S) | ≤ 0.008 |
| Iron (Fe) | Balance |
3.Physical Properties (Room Temperature Typical Values)
| Item | Typical Data |
| Modulus of Elasticity | 200 GPa |
| Density | 7.74 g/cm³ |
| Thermal Expansion (20~100℃) | 10.1×10⁻⁶ /℃ |
| Thermal Conductivity | 24.0 W/(m·K) |
| Magnetic Property | Retains magnetism regardless of heat treatment status |
4.UNS S42700 Mechanical Properties
Annealed Delivery Condition (Machining Stock)
Tensile Strength: ≥790 MPa
Yield Strength: ≥630 MPa
Brinell Hardness: ≤260 HB
Machinability: Excellent for turning, drilling, and rough forging.
Hardened & Double Tempered Condition (Final Service Finished)
Tensile Strength: ≥1820 MPa
Yield Strength: ≥1600 MPa
Hardness: 58–61 HRC
Charpy Impact Energy: 32–48 J
Performance: Exhibits excellent fatigue resistance and wear resistance, making it ideal for high-load working components.
5.Heat Treatment
Spheroidizing Annealing: Heat to 830–860°C, hold for a sufficient time, and then slowly cool in the furnace to soften the material and improve machinability.
Hardening: Gradually preheat, then austenitize at 1030–1050°C, followed by oil or high-pressure gas quenching. An optional cryogenic treatment at -78°C for 2 hours is recommended to reduce retained austenite and stabilize dimensional accuracy.
Double Tempering: Perform two separate tempering cycles at 510–540°C for 2 hours each, with air cooling between cycles. This process effectively relieves residual stresses and stabilizes the final mechanical properties.
6.Fabrication Characteristics
Machining: The high hard carbide content provides excellent wear resistance but increases grinding difficulty. Carbide cutting tools are highly recommended.
Welding: Welding is generally not recommended for standard applications due to the high carbon and alloy content, which makes the material prone to cold cracking. If welding is necessary, strict preheating and post-weld heat treatment (PWHT) are required.
Forming: The material exhibits poor cold ductility. Therefore, hot forgingis typically adopted for manufacturing complex-shaped blanks.
7. Available Product Forms
Round Bar
Flat Bar
Sheet & Plate
Seamless Pipe & Tube
Forged Flanges & Pipe Fittings
Custom CNC Machined Spare Parts
8.Typical Applications
Aerospace high-precision bearings
High-temperature valve trim & internal components
Petrochemical downhole wear-resistant shafts
Precision pump spindles
High-end medical surgical blades
Wear-resistant mold inserts
Special instrument spare parts
ABOUT US
C&N Industrial Group Limited is a leading pipe, flange and fitting manufacturer. All raw materials are provided by highly reputable suppliers, and our products all go through strict quality inspection under ISO 17025 regulation.
