35NCD16 material is a medium carbon nickel chromium molybdenum steel commonly used in the French aviation industry. This alloy steel belongs to the high toughness and high-strength structural steel category. This alloy steel contains high levels of Ni, Cr, and Mo alloying elements, making the undercooled austenite of the steel quite stable. The steel has high hardenability, and martensite and bainite structures can be obtained by air quenching. Quenching and high-temperature tempering or low-temperature tempering can achieve two levels of high strength or ultra-high strength. It can achieve uniform high strength and high toughness plasticity on large cross-sections, with low cold brittle transition temperature and high fatigue strength.
35NCD16 steel is used in the quenched and tempered (quenched+high-temperature tempered) or quenched+low-temperature tempered state, mainly for manufacturing key components with large cross-sections that withstand fatigue loads, such as shafts, butt joints, special bolts, landing gear components, etc.
In order to fully utilize the performance of 35NCD16 steel, it is usually necessary to carry out appropriate heat treatment and processing. This may include steps such as annealing, normalizing, quenching, and tempering to adjust its microstructure, hardness, and mechanical properties. In addition, it is also necessary to pay attention to following correct operating procedures during processing and installation to ensure the quality and reliability of fasteners.
Grade: 35NCD16
Corresponding standard: NF A 35-556-1984
Steel for threaded fasteners for structural and engineering purposes
Classification: Alloy steel
35NCD16 Chemical Element Content (%)
C：0.32～0.39
Si：0.17-0.37
Mn：0.50～0.80
S：≤0.020
P：≤0.020
Cr：1.60～2.00
Ni：3.60-4.10
Mo：0.25～0.45
35NCD16 heat treatment process:
- Quenching heating temperature: 850 ℃; Cooling agent: oil
- Tempering heating temperature: 560 ℃; Cooling agent: water and oil
*Note: The allowable adjustment range for heat treatment temperature is quenching ± 15 ℃, low-temperature tempering ± 20 ℃, and high-temperature tempering ± 50 ℃
35NCD16 Mechanical properties:
*Note: There are differences in performance due to different cross-sections, as follows.
- Yield strength σ s (MPa): ≥ 980
- Tensile strength σ b (MPa): ≥ 1130
- Elongation rate δ 5 (%): ≥ 10
- Reduction of area ratio (%): ≥ 50
- Impact absorption energy (Aku2/J): ≥ 71
*Note: Round steel with a diameter less than 18mm will not undergo impact energy testing.
- Annealing hardness: 269HBW
This article introduces the chemical composition, material, price, hardness, density, various forms, and application fields of quenched and tempered alloy structural steels 35Cr2Ni4Mo, 35NCD16, and 36CrNiMo16, including round steel, square steel, flat steel, hexagonal steel, etc.
