JIS SKD6 Alloy Tool Die Steel Bar(BS BH11, ONORM W300 Bars)

Product Description

JIS SKD6 represents the 5% chromium hot-work tool steel family, known more universally by its American designation, AISI H11.

While it looks practically identical on paper to its famous sibling SKD61 (H13), SKD6 is engineered with slightly less vanadium. This intentional composition tweak gives it higher impact toughness and structural ductility, making it the primary choice for deep-cavity tooling, highly stressed structural parts, and heavy-duty hot forging operations where cracking poses a greater threat than abrasive wear.

Technical Specifications & Chemical Composition

The defining difference between SKD6 (H11) and SKD61 (H13) lies in the Vanadium (V) content. SKD6 limits vanadium to around 0.30%0.50%, which significantly reduces vanadium carbide segregation, giving the steel its characteristic ultra-high fracture toughness.

Global Cross-Reference Equivalents

If you are coordinating manufacturing cross-borders, these names reference the same core alloy chemistry:

• Japan (JIS): SKD6

• USA (AISI / ASTM / UNS): H11 / UNS T20811

• United Kingdom (BS): BH11

• Austria (NORM): W300 (Bhler designation)

• Germany / Europe (DIN, EN): 1.2343 / X37CrMoV5-1

• China (GB): 4Cr5MoSiV

Performance Comparison: SKD6 (H11) vs. SKD61 (H13)

Heat Treatment & Processing Guide

SKD6 exhibits deep air-hardening capabilities. Due to its balanced chemistry, it changes dimensions very minimally during proper gas-quench or oil vacuum hardening.

1. Annealed Condition: Typically delivered in a soft-annealed state with a maximum hardness of $\le$ 229 HBW, ensuring clean machining.

2. Preheating: Heat slowly to 550C600C (1022F1112F), followed by a second uniform preheat stage at 820C850C (1508F1562F).

3. Austenitizing (Hardening): Heat to 1000C1040C (1832F1904F) and hold once the core reaches temperature.

4. Quenching: Air blast, pressurized inert gas (vacuum), or warm oil quench.

5. Tempering: Double tempering is mandatory. Heat within 540C650C (1004F1202F) depending on desired hardness. Working hardness typically targets 44 to 50 HRC.

Primary Applications

Because of its structural integrity under intense shock and cyclic thermal loading, SKD6 / H11 round bars are widely selected for:

• Heavy Forging Architecture: Forging dies, highly stressed die inserts, and hot punch tooling.

• Aviation & Structural Parts: Landing gear components, structural airframe fasteners, and drive shafts (leveraging its exceptional fatigue limit and high tensile strength when heat-treated).

• Extrusion Equipment: Die holders, backing blocks, and extrusion mandrels processing aluminum and copper.

• Hot Shear Blades: Industrial scrap and billet cutting blades subjected to sharp shock loads.