Precision carburising and case hardening services

What is carburising and case hardening?

Carburising and carbonitriding are specialised "thermochemical" techniques used to engineer a high-strength, wear-resistant surface on low-carbon steel components. The definition of carburising is the process of diffusing carbon into the surface of a solid ferrous alloy by heating the metal in a furnace in contact with carbonaceous material.

Performed at precise temperatures between 800°C and 940°C, these treatments represent the critical first stage of the case hardening process. By altering the chemical makeup of the steel’s surface, our metallurgical experts ensure that subsequent rapid cooling – or "quenching" – produces a superior dual-layer result designed for the most demanding industrial environments.

Carburising vs carbonitriding

While both processes increase surface hardness and wear resistance, carbonitriding introduces both carbon and nitrogen into the steel surface, making it particularly suitable for smaller components requiring enhanced hardness and fatigue performance.

Our team can recommend the most appropriate process based on your application and performance requirements.

The dual-layer advantage: Engineered for maximum component life

Our case hardening services are designed to protect your critical assets from the silent, structural strains that compromise steel. In our 25 years of field experience, we have found that the most resilient components utilise this dual-layer mechanical profile to prevent catastrophic failure:

• The case: A localised, rock-hard exterior (often measured in Rockwell hardness) that provides elite resistance to surface wear, abrasion and abrasive wear from dust or dirt.
• The core: A softer, shock-absorbent interior that maintains structural toughness and prevents brittleness, allowing the part to withstand heavy loads and impact.

This precise combination allows your components to remain incredibly durable on the outside without becoming brittle or prone to fatigue failure, effectively extending your equipment's operational life-cycle and reducing machinery downtime.

Common materials we carburise

National Heat regularly carburises and case hardens a range of engineering steels, including:

• 8620 steel
• EN36 and EN36A
• 20MnCr5
• 5120 steel
• Alloy steels
• Low-carbon engineering steels

Our team can assess your material specification and recommend the most suitable heat treatment process to achieve the required hardness, case depth and service life.

Common applications for carburising

Carburising is commonly used to improve wear resistance and fatigue strength in:

• Gears
• Pinions
• Shafts
• Splined components
• Sprockets
• Bushes
• Bearings
• Rollers
• Drive components
• Transmission components

Why choose National Heat for your hardening requirements?

At National Heat, we transform complex metallurgical science into predictable operational success for our partners across Australia and the Pacific Region. With a senior management team possessing over 80 years of combined experience, we provide more than just heat treatment; we provide an impenetrable shield against project downtime and asset failure.

• Verified quality & traceability: We provide comprehensive metallurgical reports and hardness certificates for every batch, ensuring your parts meet mandatory code requirements and perform exactly as engineered.
• Precision distortion control: One of the biggest concerns in heat treatment is part warping. Our workshop processes are designed to minimise distortion and maintain tight dimensional accuracy, protecting the investment you've already made in precision machining.
• Decades of reliability: Established in 1999, we have built a reputation for handling complex compliance parameters safely and efficiently for the region's largest industrial players.

Solving industrial wear and fatigue challenges

Whether you are seeking to improve gear durability or strengthen mining equipment components, our team delivers the technical precision your industry demands. We specialise in treating high-value parts, including:

• Gears and pinions
  Improving gear tooth wear and fatigue strength for mining and automotive gearboxes.
• Shafts and drive systems
  Enhancing shaft hardening for heavy machinery to prevent premature failure.
• Pins and bushes
  Creating wear resistant pins for agricultural and earthmoving equipment.

Common questions regarding carburising services (FAQ’s)

Is my material suitable for carburising?
Carburising is most effective on low carbon steels (such as 8620, EN36, or 20MnCr5) where the core carbon content is low enough to maintain toughness while the surface absorbs carbon to reach high hardness. If you are unsure if your steel can be case hardened, our senior engineers can provide a material compatibility audit.

How deep will the case hardness be?
The effective case depth is meticulously controlled by the duration and temperature of the carburising cycle. We can achieve precise depths tailored to your specific application, whether you need a thin wear-resistant layer for precision gears or a deep case for heavy-duty mining sprockets.

Will carburising cause my parts to distort?
While all furnace heat treatment carries a risk of dimensional change, National Heat utilizes advanced distortion control techniques. By managing thermal gradients and quenching parameters in our controlled facility, we maintain the integrity of threads, holes and complex geometries.

How do you verify the results?
Every batch undergoes rigorous quality assurance. We utilize calibrated Rockwell hardness testing and can provide cross-sectional microstructure analysis to verify both surface hardness and the transition to the core. This provides the documented verification required by engineers, site managers and procurement teams.

Keeping your operations moving

We understand that every day your parts sit in a furnace is a day they aren't generating revenue. Our carburising services are built for absolute operational fluidity, offering:

• Shutdown support: We accommodate urgent turnaround times to ensure your maintenance schedules remain on track.
• Code compliance: Full adherence to AGMA, ISO, and other industry-specific standards.
• Regional reach: Serving industrial hubs across Australia, including Brisbane, Sydney, Melbourne, and Perth.

"An investment in precise thermal processing today shields you from a million-dollar failure tomorrow".

Protect your legacy and your infrastructure with the team that built the region’s track record in precision heat treatment.

Not sure If carburising is right for your component?

Our experienced metallurgical team can assess your material, application and operating environment to determine whether carburising, carbonitriding or an alternative heat treatment process is best suited to your requirements.

Contact National Heat today to discuss your project or request a quote >>