Types of steel and processing parameters
Date：2025-03-28Number：1669Low Carbon Steel (e.g., 1018, A36)
Properties: Carbon content <0.3%, ductile, easy to machine.
Methods: Turning, milling, drilling.
Tools: HSS or carbide tools.
Applications: Frames, gears, enclosures.
Pros: Low cost, weldable; Cons: Low hardness, poor wear resistance.
Medium Carbon Steel (e.g., 1045, 4140)
Properties: Carbon 0.3%-0.6%, higher strength.
Methods: Use coolant to avoid overheating.
Tools: Coated carbide tools.
Applications: Shafts, molds, machinery parts.
Pros: Balanced strength/machinability; Cons: Requires heat treatment.
High Carbon Steel (e.g., 1095, D2)
Properties: Carbon >0.6%, extreme hardness.
Methods: Slow speeds to prevent chipping.
Tools: CBN or diamond tools.
Applications: Cutting tools, springs, dies.
Pros: Superior wear resistance; Cons: Brittle, difficult to machine.
Stainless Steel (e.g., 303, 316)
Properties: Chromium adds corrosion resistance.
Methods: Low feed, high RPM to avoid work hardening.
Tools: TiAlN-coated tools.
Applications: Medical devices, chemical equipment.
Pros: Corrosion-resistant; Cons: Gumminess, tool wear.
Alloy Steel (e.g., 4340, H13)
Properties: Chrome/molybdenum for strength/heat resistance.
Methods: Pre-heat treatment, post-quenching.
Tools: High-temperature carbide tools.
Applications: Aerospace, heavy-duty machinery.
Pros: High performance; Cons: Expensive, complex processing.
Coolant: Essential for stainless & high-carbon steels.
Parameters: Optimize speed/feed/depth per material.
Post-Processing: Quenching improves properties but may cause distortion.
| Grade | 1018 | A36 |
|---|---|---|
| Composition | C≤0.18%, Mn 0.6-0.9% | C≤0.26%, Mn≥0.3% |
| Hardness | 126 HB | 120-160 HB |
| Cutting Speed | 120-180 m/min (Carbide) | 90-150 m/min |
| Feed Rate | 0.15-0.3 mm/rev | 0.1-0.25 mm/rev |
| Heat Treatment | Not hardenable | Rarely treated |
| Tensile Strength | 440 MPa | 400-550 MPa |
| Applications | Bolts, pins | Structural frames |
Tip: Use chip-breaker tools for long, stringy chips.
| Grade | 1045 | 4140 |
|---|---|---|
| Composition | C 0.45%, Mn 0.6-0.9% | C 0.4%, Cr 1%, Mo 0.2% |
| Hardness | 170 HB (Annealed) | 197 HB (Annealed) |
| Cutting Speed | 100-150 m/min | 80-130 m/min |
| Feed Rate | 0.1-0.2 mm/rev | 0.08-0.15 mm/rev |
| Heat Treatment | Quench & Temper (HRC 40-55) | Oil quench + Temper (HRC 28-55) |
| Tensile Strength | 585 MPa | ≥950 MPa (After QT) |
| Applications | Gears, crankshafts | Aircraft landing gear |
Tip: Normalize 4140 before machining to reduce gumminess.
| Grade | 1095 | D2 Tool Steel |
|---|---|---|
| Composition | C 0.95%, Mn 0.3% | C 1.5%, Cr 12%, Mo 1% |
| Hardness | 190 HB (Annealed) | 240 HB (Annealed) |
| Cutting Speed | 60-100 m/min | 50-80 m/min |
| Feed Rate | 0.05-0.1 mm/rev | 0.05-0.08 mm/rev |
| Heat Treatment | Water quench (HRC 56-62) | Air quench (HRC 58-62) |
| Tensile Strength | 685 MPa | 850 MPa (Hardened) |
| Applications | Knives, springs | Blanking dies |
Critical: Pre-harden D2 to HRC 28-32 for machinability.
| Grade | 303 (Free-Machining) | 316 (Marine Grade) |
|---|---|---|
| Composition | C≤0.15%, Cr 18%, S 0.3% | C≤0.08%, Cr 16%, Ni 10%, Mo 2% |
| Hardness | 160 HB | 150 HB |
| Cutting Speed | 80-120 m/min | 60-100 m/min |
| Feed Rate | 0.1-0.2 mm/rev | 0.08-0.15 mm/rev |
| Heat Treatment | Solution Annealing (1050°C) | Same |
| Tensile Strength | 620 MPa | 580 MPa |
| Applications | Valve parts | Chemical tanks |
Note: Keep tools sharp to prevent work hardening on 316.
Tool life reference:
When machining stainless steel, tool life is 30-50% shorter than carbon steel.
High carbon steel is recommended to check tool wear every 4 hours of machining.
Coolant Selection:
Stainless steel: High lubricity emulsions (e.g., sulfur-containing extreme pressure additives).
High carbon steel: 5-10% water soluble coolant.
Surface roughness control:
Material Finishing Ra (μm)
Low carbon steel 0.8-1.6
Hardened steel 0.4-0.8 (CBN tool required)
person: Mr. Gong
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