Chrome Moly W.Nr. 12CrMo9-1 Alloy Steel Bars

Product Description

W.Nr. 1.7380 (chemically designated as 10CrMo9-10 or 12CrMo9-10 depending on the specific standard revision) is a highly specialized, low-alloy chrome-moly steel.

Unlike conventional high-tensile or case-hardening bars, this grade is engineered fundamentally as a creep-resistant, heat-resistant pressure vessel steel. Packed with roughly 2.25% chromium and 1% molybdenum, it is built to survive prolonged, continuous stress in elevated temperature zones (up to 600°C) where standard carbon and alloy steels would deform, oxidize, or suffer catastrophic creep rupture.

Global Equivalents

Because this alloy is critical for heavy industrial boilers and refinery infrastructures worldwide, it maps directly to highly recognized pressure vessel standards:

• USA (ASTM / ASME): ASTM A387 Grade 22 / A182 F22 (Forgings/Bars)

• Germany (DIN / WNr): 10CrMo9-10 (1.7380) / Old: 12CrMo9-10

• Europe (EN): 11CrMo9-10 (1.7383)

• France (AFNOR): 10CD9-10

• UK (BS): 1503-622 / 622Gr31

Chemical Composition (Typical %)

The "2.25Cr-1Mo" chemistry profile is tightly controlled. The elevated chromium delivers robust resistance to high-temperature scale and oxidation, while the molybdenum provides structural creep resistance under extreme hot pressure.

Mechanical Properties (Normalized & Tempered, +NT)

Bars are typically delivered in a normalized and tempered state to stabilize the microstructure for elevated thermal applications.

• Tensile Strength ($R_m$): 520 – 670 MPa

• Yield Strength ($R_{e}$): ≥ 310 – 330 MPa

• Elongation ($A$): ≥ 18% (Excellent ductility to combat thermal expansion cycling)

• Impact Energy (Charpy-V, 20°C): ≥ 40 J

• Hardness Range: Typically 160 – 210 HBW

Distinct Technical Advantages

• Superior Creep Resistance: It resists the slow, progressive deformation (creep) that metals undergo when subjected to high stress at elevated temperatures over long service lives.

• Hydrogen Attack Resistance: The high chromium content binds carbon effectively, making the alloy highly resistant to high-temperature hydrogen attack (HTHA) and structural embrittlement in chemical environments.

• Good Hot Weldability: Because the carbon remains low, it can be welded reliably using matched fillers (like E9018-B3), though standard industrial procedures mandate preheating and post-weld heat treatment (PWHT) to relieve residual stress.

Common Industrial Applications

You will rarely see 1.7380 used for standard automotive gears or structural brackets; instead, these alloy bars and forgings are essential for high-heat, high-pressure processing fields:

• Petrochemical & Refineries: High-temperature hydrocracker components, catalytic reformers, heat exchanger tube sheets, and processing flanges.

• Power Plant Generation: Main steam pipelines, boiler header blocks, superheater supports, and valve bodies operating at supercritical temperatures.

• Heavy Hardware: Specialized high-temperature structural bolts and threaded ties exposed to continuous heat inside industrial furnaces.