Types of Heat Treatment Services in India — Complete Guide | SR Thermal
Types of Heat Treatment Services in India — Which Process Does Your Component Need?
If you’re a manufacturer in India looking for heat treatment services, you’ve probably realized that choosing the right process isn’t straightforward. There are over a dozen types of heat treatment — each designed for different materials, components, and end-use requirements. Selecting the wrong process means wasted money, delayed production, and components that don’t meet specifications.
This guide covers every major type of heat treatment service available in India, explains what each process does, and helps you determine which one is right for your specific components. Whether you’re manufacturing automotive gears, injection moulds, or aerospace fasteners — understanding these processes will help you make better decisions and find the right heat treatment partner.
What Are Heat Treatment Services?
Heat treatment services are controlled thermal processes used to alter the physical and mechanical properties of metals — including hardness, strength, ductility, toughness, and wear resistance. These services are essential across Indian manufacturing, from the automotive belt of Pune and Chennai to the aerospace hubs of Bangalore and Hyderabad.
Heat treatment doesn’t change the shape of a component — it changes its internal structure at a molecular level, transforming ordinary steel into a high-performance engineering material.
The most common types of heat treatment services in India include gas nitriding, carburizing, hardening and tempering, annealing, normalizing, stress relieving, and vacuum heat treatment. Each process operates at different temperatures, atmospheres, and cooling methods — and each produces very different results.
Gas Nitriding — Surface Hardening Without Distortion
Gas nitriding is one of the most advanced surface hardening processes available in India. It works by diffusing nitrogen into the surface of steel at temperatures between 495°C and 565°C — well below the transformation temperature of most steels. This means components undergo minimal to zero dimensional change during the process.
How gas nitriding works:
Components are placed inside a sealed furnace and exposed to ammonia gas (NH₃). At the process temperature, ammonia dissociates into nitrogen and hydrogen. The nitrogen atoms diffuse into the steel surface, forming hard iron nitrides that create an extremely wear-resistant surface layer (typically 0.1 to 0.8 mm deep).
Best suited for:
- Crankshafts and camshafts (automotive)
- Gears and splines
- Injection moulds and die casting dies (H13, P20)
- Extruder screws and barrels
- Precision spindles and machine tool parts
Why manufacturers choose gas nitriding:
- No quenching required — zero distortion
- Excellent fatigue strength improvement (up to 50% improvement)
- Superior wear resistance and corrosion resistance
- Can be applied to finished, ground components without rework
SR Thermal Solution operates a horizontal gas nitriding furnace with 1,200 kg batch capacity in Pune — one of the largest gas nitriding job work facilities in Western India.
[INTERNAL LINK: Learn more about our gas nitriding job work service → /nitriding-jobwork-services/]
Ferritic Nitro Carburizing (FNC) — Wear + Corrosion Resistance
FNC is a modified nitriding process that introduces both nitrogen and carbon into the component surface at around 570°C. The process creates a compound layer (white layer) that provides excellent wear and corrosion resistance.
FNC is particularly popular in the automotive industry as a cost-effective replacement for hard chrome plating.
Best suited for:
- Brake rotors and drums
- Cylinder liners and piston rings
- Hydraulic valve bodies
- Fasteners and bolts
- Textile machinery components
[INTERNAL LINK: View all our heat treatment services in India → /heat-treatment-services-in-india/]
Oxy Nitro Carburizing (ONC) — Black Finish + Protection
ONC is an extension of the FNC process with an additional controlled oxidation step. The result is a component with a dense black oxide layer over the nitrided surface — providing both corrosion protection and an aesthetically appealing dark finish.
Best suited for:
- Hand tools and machine tools
- Hydraulic components
- Automotive fasteners
- Any application where visual appearance + corrosion resistance are both important
ONC eliminates the need for separate painting or black oxide coating — the finish is integral and far more durable than surface coatings.
Carburizing & Case Hardening — Deep Hard Case
Carburizing is the process of diffusing carbon into the surface of low-carbon steel at temperatures between 850°C and 950°C. After carburizing, the component is quenched (rapid cooled) to create a hard, wear-resistant outer case over a tough, shock-absorbing core.
This is one of the most widely used heat treatment processes in India’s automotive sector.
Case depth achieved:
0.3 mm to 3.0 mm (depending on time and temperature)
Best suited for:
- Gears and gear shafts (automotive transmission)
- Bearing races and rollers
- Cam followers and rocker arms
- Crown wheels and pinions
- Any component needing a hard surface + tough core combination
[H3] Carburizing vs Gas Nitriding:
Carburizing gives deeper case depth but causes distortion (requires post-grinding). Gas nitriding gives shallower case but with zero distortion — ideal for finished components. The choice depends on your component’s requirements.
[H2] Hardening & Tempering — Full-Section Strength
Through-hardening involves heating the entire component to its austenitizing temperature (typically 800–880°C), quenching in oil or water, and then tempering at a lower temperature (150–600°C) to achieve the desired balance of hardness and toughness.
Unlike case hardening (which only hardens the surface), through-hardening transforms the entire cross-section of the component.
[H3] Best suited for:
- Shafts, pins, and axles
- Springs and spring steel components
- Bolts and high-strength fasteners
- Structural components requiring uniform hardness
Hardness range: 28–65 HRC depending on steel grade and temper temperature.
[H2] Annealing — Softening for Machinability
Annealing involves heating metal to a specific temperature and then slowly cooling it (usually inside the furnace). The purpose is to soften the material, relieve internal stresses, and improve machinability.
[H3] Types of annealing:
- Full annealing — complete softening (slow furnace cooling)
- Spheroidize annealing — for high-carbon steels to improve cold forming
- Process annealing — intermediate softening between cold working stages
[H3] Best suited for:
- Forgings and castings before machining
- Cold-worked sheet metal and wire
- Tool steels requiring re-softening after heat treatment
[H2] Normalizing — Uniform Grain Structure
Normalizing is similar to annealing but involves air cooling instead of slow furnace cooling. This produces a finer, more uniform grain structure with slightly higher hardness than annealed material.
[H3] Best suited for:
- Forgings and castings needing grain refinement
- Weldments requiring uniform properties across HAZ (heat-affected zone)
- Components where consistent machining response is critical
[H2] Stress Relieving — Prevent Warping & Cracking
Stress relieving is a sub-critical heat treatment (typically 550–650°C for steel) designed to reduce residual stresses caused by welding, machining, cold forming, or previous heat treatment. The component is heated slowly, held at temperature, and cooled slowly.
[H3] Best suited for:
- Welded fabrications and structures
- Machined components with tight tolerances
- Castings and forgings
- Any component experiencing in-service distortion or cracking
Stress relieving does not significantly change hardness or mechanical properties — it simply makes the component dimensionally stable.
[H2] Vacuum Heat Treatment — Clean, Precision Processing
Vacuum heat treatment is performed in an oxygen-free environment, eliminating surface oxidation and decarburization. Components come out bright, clean, and with precise hardness control.
[H3] Best suited for:
- Tool steels (H13, D2, M2, S7)
- Injection moulds and precision dies
- Aerospace-grade components
- Medical instruments
- Any application demanding the highest surface quality
Vacuum hardening is typically more expensive than conventional atmosphere hardening but delivers superior results for high-value components.
[H2] How to Choose the Right Heat Treatment Process
Selecting the right heat treatment depends on four key factors:
1. Material Grade — Different steels respond to different processes. Alloy steels work well with nitriding; low-carbon steels need carburizing; tool steels often need vacuum hardening.
2. Required Properties — Do you need surface hardness only (nitriding, carburizing) or through-hardness (hardening & tempering)? Do you need corrosion resistance (ONC, FNC)?
3. Dimensional Tolerance — If your component is already finished to final size, you need a low-distortion process like gas nitriding. If post-grinding is acceptable, carburizing or through-hardening work fine.
4. Production Volume — Some processes (like gas nitriding) run for 15–100 hours per batch. Others (like induction hardening) take minutes. Your production timeline matters.
If you’re unsure which process is right for your component, SR Thermal Solution offers free technical consultation. Send your component drawing and material grade to srthermal.solution@gmail.com — our team will recommend the optimal process.
[INTERNAL LINK: Explore all our heat treatment services in India → /heat-treatment-services-in-india/]
[H2] Where to Get Heat Treatment Services in India
SR Thermal Solution (Nitride Technology) provides comprehensive heat treatment services from our ISO-certified facility in Pune, Maharashtra. We serve manufacturers across India — from automotive OEMs in Chennai and Gurugram to tool makers in Mumbai and Rajkot.
Our services include:
- Gas Nitriding (1,200 kg batch capacity)
- Ferritic Nitro Carburizing (FNC)
- Oxy Nitro Carburizing (ONC)
- Vacuum Hardening
- Carburizing & Case Hardening
- Tempering & Stress Relieving
We also manufacture gas nitriding furnaces — so when you choose SR Thermal for heat treatment job work, you’re working with a team that builds, operates, and maintains its own furnace systems.
Contact us for a free quote:
Phone: +91 8378848736 / +91 8975966868
Email: srthermal.solution@gmail.com
Location: Chikhali, Pune – 411062, Maharashtra, India
[BUTTON: Get a Free Quote → /contact/]
[BUTTON: View Our Heat Treatment Job Work Services → /heat-treatment-job-work-services-in-india/]