SKD11 Steel Technical Overview

1. Overview of SKD11 Steel

SKD11 tool steel is a high-performance cold work tool steel specified under the Japanese Industrial Standard JIS G4404 for alloy tool steels. It is a principal material within the cold work die steel category, recognized for its versatility and reliability.

2. Key Characteristics and Chemical Composition

SKD11 steel is valued for its high wear resistance and toughness, making it a suitable general-purpose choice for many demanding tooling applications. Its dependable performance is rooted in its high-carbon, high-chromium alloy composition and a clean, homogeneous microstructure, typically achieved through vacuum degassing refinement during production.

The typical chemical composition that defines SKD11’s properties includes:

• Carbon (C): 1.40 – 1.60% – Essential for forming hard carbides with excellent wear resistance.
• Chromium (Cr): 11.00 – 13.00% – Enhances hardenability, contributes significantly to wear resistance via chromium carbides, and provides a degree of corrosion resistance.
• Molybdenum (Mo): 0.80 – 1.20% – Increases hardenability and strength at higher temperatures.
• Vanadium (V): 0.20 – 0.50% – Promotes the formation of fine carbides, further improving wear resistance and toughness.
• Silicon (Si): ≤ 0.40%
• Manganese (Mn): ≤ 0.60%
• (Impurities like Phosphorus (P) and Sulfur (S) are kept to low levels).

3. Supply Condition and Heat Treatment Guidelines for SKD11 tool steel 

Aobo Steel typically supplies SKD11 in the annealed condition, usually with a hardness of ≤255 HBW. This state allows for easier machining before the critical heat treatment process.

Achieving the desired final properties in SKD11 necessitates precise heat treatment.

4. SKD11 tool steel  Hardening Process

A common hardening procedure involves:

• Preheating Stage 1: 500-650°C
• Preheating Stage 2: 800-850°C
• Austenitizing: 1030-1050°C
• Quenching: Air cooling is standard and minimizes distortion due to its good hardenability. For larger or complex parts, oil quenching (down to approx. 200°C) or staged quenching in a salt bath (250-500°C), followed by air cooling, can be used to manage internal stresses. Uniform cooling is crucial to minimize deformation.

5. Tempering

Tempering adjusts the final balance between hardness and toughness:

• Standard Practice: Double tempering at 500°C or higher, followed by air cooling, is typical.
• For Maximum Hardness (approx. 60-61 HRC) with Good Toughness: Tempering at a lower temperature, around 180°C, may be employed.
• For Higher Hardness (approx. 62-63 HRC) with Reasonable Toughness: Tempering in the 520-540°C range is often preferred, avoiding a potential toughness dip associated with the 500°C region.
• Note: Dimensional changes occur during heat treatment; these must be accounted for in high-precision tooling design.

6. Common Applications for SKD11 tool steel

The excellent combination of wear resistance and toughness makes SKD11 widely applicable in various cold-working processes:

• Precision Blanking Dies
• Cold Forging Dies
• Cold Extrusion Dies
• Deep Drawing Dies
• Flanging Dies
• Forming Rolls
• Wear-Resistant Components in Plastic Molding Dies
• (SKD11 can demonstrate significantly longer service life in some metal-forming tasks than certain high-speed steels like SKH51).

7. Equivalent Steel Grades and Variants

SKD11 is internationally recognized and corresponds to several other standard designations. While considered equivalent, minor variations in exact composition or production methods may exist between grades.

• AISI/SAE (USA): D2
• DIN (Germany): 1.2379 / X155CrVMo12-1
• GB (China): Cr12Mo1V1
• KS (Korea): STD11
• ASSAB (Sweden): XW-42
• Bohler (Austria): K110
• Other Japanese Brands: Hitachi SLD, Daido DC11, Nachi CDS11

8. Modified Grades

Variations of SKD11 exist, offering enhanced properties for specific needs:

• KD11S (KOSHUHA): Focuses on improved machinability and fatigue resistance via controlled carbide structure.
• SW-SKD11: Emphasizes a balance of strength, toughness, and wear resistance with minimized heat treatment deformation.
• STD11: Noted as an air-cooled version with high cleanliness.
• QCM8: Blends SKD11 characteristics with matrix high-speed steel features for enhanced wear resistance and hardenability.