Induction Heat Treatment for 4140 & 4150 Steel Grades
Detailed guide to hardening processes and ideal temperatures for 4140 and 4150 alloy steels.
Introduction: Why 4140 & 4150 Steels Are Industry Favorites
In Punjab’s rapidly growing industrial manufacturing sector — especially Ludhiana, known for its engineering and automotive components — 4140 and 4150 alloy steels are among the most widely used materials. These steels offer a perfect balance of strength, ductility, and wear resistance, making them ideal for shafts, gears, axles, bolts, and tooling components. However, to unlock their full mechanical potential, these steels require precision-controlled heat treatment — specifically induction hardening.
At Thakur Induction, we specialize in 4140 steel induction hardening and 4150 heat treatment job work, serving automotive, machinery, and forging industries across Punjab and North India.
Understanding 4140 & 4150 Alloy Steels
Both 4140 and 4150 are chromium-molybdenum (Cr-Mo) alloy steels known for excellent toughness, strength, and fatigue resistance.
| Property | 4140 Steel | 4150 Steel |
|---|---|---|
| Carbon (%) | 0.38–0.43 | 0.48–0.53 |
| Chromium (%) | 0.8–1.1 | 0.8–1.1 |
| Molybdenum (%) | 0.15–0.25 | 0.15–0.25 |
| Tensile Strength (After Treatment) | 850–1000 MPa | 900–1100 MPa |
| Machinability | Good | Moderate |
| Hardenability | Excellent | Very high |
The slightly higher carbon content in 4150 allows deeper hardening and higher achievable hardness levels.
Why Induction Hardening Is Ideal for 4140 & 4150 Steels
- Localized Hardening with Core Toughness: Induction hardening allows precise heating of specific areas like journals, gear teeth, or bearing surfaces — achieving high surface hardness while preserving the ductile core.
- Deeper Hardness Penetration: These steels respond well to medium-frequency induction systems (10–30 kHz), enabling case depths of 2.5–5.0 mm depending on application.
- Excellent Fatigue and Impact Strength: The combination of a hard case and a tough core ensures superior fatigue life — ideal for shafts, gears, and spindles that experience repetitive stress.
- Distortion-Free Results: Controlled heating and quenching reduce dimensional changes, which is critical for precision-machined components.
Ideal Heat Treatment Parameters for 4140 & 4150 Steels
| Parameter | 4140 Steel | 4150 Steel |
|---|---|---|
| Austenitizing Temperature | 840–880°C | 850–900°C |
| Quenching Medium | 8–12% Polymer Solution or Water | 8–10% Polymer Solution |
| Tempering Range | 150–250°C | 150–250°C |
| Resulting Hardness (HRC) | 55–60 | 56–62 |
| Case Depth | 2.5–4.0 mm | 3.0–5.0 mm |
| Core Hardness (Post Treatment) | 25–35 HRC | 28–38 HRC |
Polymer quenching provides a more uniform cooling rate — essential for avoiding cracks or distortion.
Induction Hardening Process for 4140 & 4150 Components
At Thakur Induction, Ludhiana, we follow a multi-stage controlled process for all alloy steel hardening operations:
- Pre-cleaning: Removal of oil, scale, and contaminants.
- Coil Design: Custom-designed coils ensure even magnetic coupling for the part geometry.
- Induction Heating: Localized heating to 850–900°C using medium-frequency systems.
- Quenching: Immediate polymer or water spray cooling.
- Tempering: Post-hardening tempering relieves stresses and enhances toughness.
- Quality Testing: Hardness and case depth are verified for every batch.
We maintain ±10°C temperature control and ±0.1 sec dwell time accuracy for consistent results.
Conclusion: Controlled Hardening = Long-Lasting Performance
Both 4140 and 4150 alloy steels deliver exceptional performance when heat-treated correctly. Through precise induction hardening, controlled case depth, and polymer quenching, we enhance their strength, fatigue resistance, dimensional accuracy, and service life. At Thakur Induction, Ludhiana, we combine engineering precision with metallurgical excellence to ensure your components perform reliably under demanding conditions.
Need Heat Treatment for 4140 & 4150?
Partner with Punjab’s leading industrial heat treatment service provider. Contact Thakur Induction for your job work needs.