AFNOR Z6CNU17-04 Stainless Steel Bars

Product Description

Physical Properties of Z6CNU17-04

When performing finite element analysis (FEA) or thermal calculation layouts on parts machined from these bars, use the following physical baseline values (evaluated at room temperature, $20^\circ\text{C}$):

• Density: $7.80\text{ g/cm}^3$ ($0.282\text{ lb/in}^3$)

• Modulus of Elasticity (E): $196\text{ GPa}$ ($28.4 \times 10^6\text{ psi}$) in the annealed condition; increases slightly to approx. $200\text{ GPa}$ after aging.

• Thermal Conductivity: $16.0\text{ W/(m}\cdot\text{K)}$

• Mean Coefficient of Thermal Expansion (CTE): $10.8 \times 10^{-6}\text{ /}^\circ\text{C}$ (over the range of $20\text{--}100^\circ\text{C}$)

• Electrical Resistivity: $0.80\text{ }\mu\Omega\cdot\text{m}$

Deep Dive: The European Impact Value (Charpy V-Notch) Mandate

While US specifications (ASTM A564) focus heavily on minimum Rockwell C (HRC) hardness and tensile properties, European and French standards (NF EN 10088-3) enforce strict Charpy V-Notch (KV) impact toughness minimums on bars, especially for subsea, high-pressure, or aerospace load paths.

The aging temperature drastically dictates whether the material will behave in a ductile or brittle manner under sudden shock loads:

 [ Mechanical Toughness vs. Aging Trade-off ] High Strength / Low Toughness Low Strength / High Toughness ─────────────────────────────── ─────────────────────────────── Condition: +P1200 (H900) Condition: +P930 (H1150) Yield: ≥ 1000 MPa Yield: ≥ 720 MPa Impact Energy (KV): ~15–20 Joules Impact Energy (KV): ≥ 75 Joules

• The Takeaway: If your bar is designated for rotating shafts, dynamic clamping hardware, or pressure boundary components, specifying a lower aging treatment like +P960 (H1075) or +P930 (H1150) is mandatory to clear structural safety regulations regarding crack propagation.

Machine Tooling & Feed Guidelines for Bars

Because Z6CNU17-04 features a highly abrasive structure once copper starts precipitating, always complete heavy metal removal while the bar stock is in the Solution Annealed (+A) state.

Turning & Milling (Condition +A)

• Tooling Type: Premium grade coated carbide (CVD or PVD TiAlN) or high-vanadium High-Speed Steel (HSS-Co).

• Cutting Speed ($V_c$): $90\text{ to }140\text{ m/min}$ for carbide turning tools; scale back to $20\text{ to }30\text{ m/min}$ if using HSS drills.

• Chip Breaking: Martensitic stainless steels produce gummy, continuous chips in the annealed state. Utilize high-pressure coolant (70+ bar) and aggressive chip-breaker geometries to prevent bird-nesting around the lathe chuck.

Post-Aging Scale Removal

If you age the machined parts in an open-atmosphere furnace, a thin, tight, bronze/straw-colored oxide scale will form. It can be removed via:

• Chemical Pickling: A bath of Nitric-Hydrofluoric acid ($HNO_3\text{--}HF$).

• Mechanical Blasting: Light glass-bead or aluminum-oxide blasting (avoid carbon-steel shot to prevent iron contamination on the surface).