18NiCrMo14-6 - Round Bar B31 EN 1-3533 AISI 3316 20Ch2N4A Bars

Product Description

The material string you provided references a ultra-high-performance Nickel-Chromium-Molybdenum (Ni-Cr-Mo) case-hardening steel. Packed with an unusually high nickel content (roughly $3.25\% - 3.75\%$), this specific alloy family is engineered for massive component cross-sections that must survive extreme dynamic stresses, shock loading, and fatigue.

Here is how your specific designations map across international material tracking systems to the same core material profile:

The Global Designation Matrix

• Euronorm (EN): 18NiCrMo14-6

• German Material Number: W.Nr. 1.3533 (specifically treated as a premium bearing quality grade)

• USA Standard: AISI 3316 / SAE 3316 (frequently designated as AISI E3316 for electric-arc furnace melting)

• Russian Standard (GOST): 20Ch2N4A (20Ð¥2Н4А / 20Kh2N4A)

• Chinese Standard (GB): 20Cr2Ni4A

• Internal Mill Designation: B31 (often used by regional European alloy mills)

Chemical Composition (Typical %)

The high combination of Nickel ($\text{Ni}$) and Chromium ($\text{Cr}$) provides incredible through-hardening depth, ensuring that even thick, heavy-diameter bars achieve uniform hardness down to their core.

Mechanical Performance (Post Heat-Treatment Core Properties)

Because this is primarily a case-hardening steel, the raw core of the bar beneath the carburized "skin" retains massive tensile limits and high fracture toughness:

• Tensile Strength ($R_m$): $\ge 1100 - 1270 \text{ MPa}$

• Yield Strength ($R_e$): $\ge 850 - 1080 \text{ MPa}$

• Elongation ($A_5$): $\ge 9\% - 11\%$

• Impact Toughness (Charpy-V): $\ge 60\text{ J}$

• Post-Carburization Surface Hardness: $58 - 62\text{ HRC}$

• Soft Annealed Delivery State: $\le 255 - 269\text{ HBW}$ (for pre-machining)

Critical Engineering Characteristics

• Deep Hardenability: Thanks to the $3.5\%$ nominal Nickel addition, large-diameter round bars do not experience the "soft center" phenomenon typical of lower-alloy steels. The core transforms reliably into high-strength tempered martensite.

• Isotropic and Ultra-Clean Profiles: Under designations like 1.3533, this grade is frequently processed via vacuum degassing or ladle refining to satisfy bearing-grade cleanliness metrics, drastically lowering micro-inclusions and maximizing multi-axial fatigue limits.

• Non-Weldable Warning: Due to the combination of high nickel/chrome levels and high hardenability, components made from this grade are not considered weldable. Attempting to weld them induces intense localized brittleness and cracking risks.

Typical Applications

These premium round bars are explicitly sourced for critical industrial components subjected to relentless, high-impact fatigue cycles:

• Aerospace & Defense: High-stress aircraft engine gears, structural planetary shafts, and heavy-duty actuator arms.

• Heavy Powertrains: Massive transmission sprockets, earthmover final drives, marine propeller shafts, and heavy-duty piston pins.

• Industrial Fastening: High-tensile, heavy-duty structural screws and clamping bars operating under extreme dynamic strain.