5CrW2Si Tool Steel: Technical Specifications and Applications

At Aobo Steel, with our extensive experience in forging tool steel for over 20 years, we understand the importance of precise material selection. Here’s a straightforward look at 5CrW2Si tool steel, a versatile alloy tool steel known for its toughness.

1. 5CrW2Si tool steel Chemical Composition (GB/T 1299-2000)

Understanding the exact chemistry is crucial. According to the GB/T 1299-2000 standard, the composition of 5CrW2Si steel is:

• Carbon (C): 0.45% – 0.55%
• Silicon (Si): 0.50% – 0.80%
• Manganese (Mn): max0.40%
• Chromium (Cr): 1.00% – 1.30%
• Tungsten (W): 2.00% – 2.50%
• Phosphorus (P): max0.030%
• Sulfur (S): max0.030%

Note: International standards may differ slightly. Specifying the required standard for your application is essential.

2. Comparison with International Standards

For reference, here are compositions for comparable grades under other standards:

• EN ISO 4957:2001 (50WCrV8): C 0.45-0.55%, Cr 1.70-2.20%, W 0.70-1.10%, V 0.15-0.45%
• JIS G4404:2006 (SKS4): C 0.45-0.55%, Cr 0.50-1.00%, W 0.50-1.00%
• ГОСТ 5950-2000 (5ХВ2С / 5XB2C): C 0.45-0.55%, Cr 0.90-1.20%, W 1.80-2.30%, Si 0.80-1.10%, Mn 0.15-0.45%, V 0.15-0.30%

3. 5CrW2Si tool steel Key Physical Properties

Understanding these properties is vital for heat treatment planning:

3.1 Critical Temperatures (Approximate)

• Ac1: 775∘C
• Ac3: 860∘C
• Ar1: 775∘C 
• Ms (Martensite start): 295∘C

3.2 Linear Expansion Coefficients (Approximate)

• 100−250∘C: 13.15×10−6/∘C
• 250−350∘C: 13.6×10−6/∘C
• 350−600∘C: 13.8×10−6/∘C
• 600−700∘C: 14.2×10−6/∘C

4. 5CrW2Si tool steel Heat Treatment Procedures

Correct heat treatment is fundamental to achieving the desired performance from 5CrW2Si. Our experience guides these common practices:

4.1 Preparatory Heat Treatment (Annealing)

• Ordinary Annealing: Heat to 800−820∘C, hold 3-5 hrs, furnace cool (≤30∘C/hr) to 600−650∘C, then air cool. Target hardness: $\le 229$ HBW. Microstructure: Granular pearlite, small carbides.
• Isothermal Annealing: Heat to 830−840∘C, hold 2-3 hrs, furnace cool to 680−700∘C, hold 3-4 hrs, furnace cool to 500∘C, then air cool. Target hardness: $\le 229$ HBW.
• High-Temperature Tempering (Post-Forging): Heat to 710−740∘C, hold 3-6 hrs, furnace or air cool. Improves machinability. Hardness: 207-255 HBW. Microstructure: Granular pearlite, small carbides.

4.2 Hardening (Quenching)

• Quenching Temperature: 860−900∘C.
• Quenching Medium: Oil (20−40∘C). Cool until the part reaches oil temperature.
• Post-Quench Hardness: $\ge 55$ HRC.

4.3Tempering

Tempering adjusts hardness and improves toughness:

• Stress Relief/Stabilization: Temper at 200−250∘C (oil or molten alkali). Air cool. Hardness: 53-58 HRC.
• Hardness Reduction/Stress Relief: Temper at 430−470∘C (air furnace or molten alkali/nitrate). Air cool. Hardness: 45-50 HRC.

Hardness vs. Tempering Temperature (Approximate, after 880°C Oil Quench):

• 100∘C: ~55 HRC
• 200∘C: ~53.5 HRC
• 300∘C: ~51 HRC
• 400∘C: ~47 HRC
• 500∘C: ~41 HRC
• 600∘C: ~33 HRC

5. Mechanical Properties and Characteristics

• Toughness: Good toughness after tempering, aided by Tungsten (W) refining grain size.
• Overall Properties: Exhibits good comprehensive mechanical properties.
• Hardenability: Relatively low carbon content means hardenability isn’t extremely high, but surface hardness can be increased via carburizing.
• Temper Brittleness: Slight risk in the 300−350∘C tempering range. Tempering around 250∘C (54-56 HRC) or 450∘C (50-52 HRC) offers good balances of hardness and toughness.
• Considerations: It is sensitive to decarburization during heating. Quenching deformation requires careful control. Wear resistance under abrasion and impact toughness are lower than those of some specialized Mo-Ni steels.

6. Common Applications

5CrW2Si is suitable for tools and dies facing impact and wear:

• Manual and pneumatic chisels, air hammer tools, rivet tools
• Cold punching dies, shear blades (cold cutting), blanking/trimming dies
• Heavy-duty cold heading punches
• Medium-load steel plate piercing punches
• Precision dies
• Woodworking tools
• Cutters for threading dies
• Hot work applications: Punching/piercing tools, shear dies, hot forging dies, die-casting molds (fusible alloys)
• Large/medium heavy-duty round scissors and long shear blades

7. Comparison with Similar Grades

• vs. 4CrW2Si: Similar performance. 5CrW2Si generally offers slightly better hardenability and high-temperature strength.
• vs. 6CrW2Si: 5CrW2Si has better toughness but slightly lower temper resistance and wear resistance. 6CrW2Si is often chosen when wear/collapse are primary failure modes.

8. Equivalent Steel Grades

For international reference:

• ISO: 50WCrV8
• EN: 50WCrV8
• JIS (Japan): SKS4
• ГОСТ (Russia): 5ХВ2С (5XB2C)
• ASTM/UNS (USA): T41901
• DIN (Germany): 45WCrV7