In the world of alloy steel, few materials match the performance and versatility of 42CrMo4+QT. It’s more than just a steel grade—it’s a metallurgical solution for components subjected to extreme mechanical stress. At Behari Lal Engineering, a trusted name among QT steel manufacturers in India, we specialize in producing high-performance, heat-treated steels tailored for demanding industrial applications.

What Is 42CrMo4+QT?

42CrMo4+QT is a quench and tempered (QT) alloy steel that combines high strength, hardness, and excellent toughness, making it a universal material for high-load applications. It is widely used in the manufacturing of:

• High-strength bolts
• Gears and pinions
• Transmission shafts
• Engine components
• Connecting rods

Its ability to withstand dynamic loading, fatigue, and impact stress makes it ideal for both mechanical and structural components under harsh operating conditions.

Chemical Composition of 42CrMo4

This chromium-molybdenum (Cr-Mo) alloy steel derives its strength and hardenability from its finely balanced chemistry:

Element	Content (%)
Carbon (C)	0.38 – 0.45
Silicon (Si)	0.60 – 0.90
Manganese (Mn)	0.60 – 0.90
Chromium (Cr)	0.90 – 1.20
Molybdenum (Mo)	0.15 – 0.30
Others	P, S (trace)

This composition offers an optimal base for QT heat treatment, which significantly upgrades the material’s internal structure and mechanical capabilities.

What Does QT Mean?

QT refers to Quenching and Tempering, a dual-stage heat treatment process:

• Quenching: The steel is heated above its critical temperature (typically 840–880°C), then rapidly cooled—usually in oil or water. This creates a martensitic microstructure, imparting high hardness and tensile strength.
• Tempering: The quenched steel is then reheated to a lower temperature (generally between 500–650°C) and held for a specific time. This reduces brittleness, refines the grain structure, and improves toughness and ductility.

At Behari Lal Ispat, we control this entire cycle with precision furnaces and continuous monitoring, ensuring uniform treatment across every millimetre of the round steel section.

Why 42CrMo4+QT?

This material isn’t chosen by accident—its properties are engineered through metallurgy to meet specific industry needs. Here’s why it’s a staple alloy in modern manufacturing:

1. High Strength & Hardness

After quenching and tempering, 42CrMo4+QT exhibits high yield and tensile strength, enabling it to perform under static and dynamic loads without deformation.

2. Superior Toughness

tempered martensite phase increases fracture resistance, making it suitable for components exposed to impact, vibration, or cyclic stresses.

3. Machinability

Despite its strength, 42CrMo4+QT maintains excellent machinability for turning, drilling, and milling operations—reducing tool wear and machining time.

4. Fatigue Resistance

Its fine-grain structure and clean chemistry offer excellent fatigue life, particularly valuable in automotive, aerospace, and heavy machinery applications.

Applications of 42CrMo4+QT

Due to its mechanical robustness and wear resistance, this steel is widely used across:

• Automotive and commercial vehicle OEMs
• Railway axle and crank components
• Forging and tool manufacturing
• Agricultural and construction machinery
• Power transmission and gear systems

Its reliability under torque, pressure, and thermal cycling is unmatched in its class.

QT Steel Manufacturing at Behari Lal Engineering

As one of the leading QT steel manufacturers in India, Behari Lal Engineering delivers round, forged, and machined steel bars in 42CrMo4+QT and other QT-treated grades, with:

• ISO-certified production systems
• Batch traceability and test certifications
• In-house metallurgical lab for microstructure analysis and hardness testing
• Custom dimensions, lengths, and mechanical specs on request

We ensure every piece of QT steel meets stringent performance parameters—because in critical applications, there’s no room for compromise.

Conclusion

When you need steel that won’t back down under pressure, 42CrMo4+QT is your alloy—and Behari Lal Engineering is your partner. As a proven QT steel manufacturer in India, we combine metallurgical science, thermal precision, and decades of experience to deliver steel that stands up to your most demanding applications.

Looking for reliable QT-treated alloy steel?

Contact Behari Lal Engineering - where metallurgy meets mission-critical performance.