Nitriding Salt

Nitriding Salt

Salt bath nitrocarburising to diffuse nitrogen and carbon into steel surfaces — improving wear resistance, anti-seizure and scuffing resistance without distortion.

Nitriding Salt — for salt bath nitrocarburising of steel components
Working Range
560°C – 570°C
Dip Time
90 – 130 min
Case Depth
10 – 20 µm
Documentation
COA · MSDS · TDS

Product Overview

Nitriding Salt is a cyanate-based salt bath compound for the liquid nitrocarburising (salt bath nitriding) process. At 560°C–570°C, the molten salt diffuses nitrogen and a small amount of carbon into the steel surface — forming a hard compound layer that dramatically improves wear resistance, anti-seizure properties and scuffing resistance.

The process uses two salts together: the base nitriding salt and a regenerator salt (Hard Temp CN2). The regenerator replenishes the CNO content consumed during treatment, keeping the bath within specification. Because the process temperature is well below the steel's transformation range, components experience minimal distortion — a critical advantage over higher-temperature surface treatments.

Technical Specifications

Salt TypeCyanate-base liquid nitriding salt
ProcessNitrocarburising (Salt Bath Nitriding)
Working Temperature560°C – 570°C (±5°C)
Initial Melt Temperature580°C
CNO Content (Bath)31 – 40%
CO₃ Content (Bath)17 – 21%
CN Content (Bath)1.0% maximum
Preheat RequiredBelow 400°C for 15–30 min
Dip Time90–130 min (varies by section size)
Case Depth10–15 µm standard; up to 20 µm achievable
Packaging25 kg HDPE sealed bags
Bath MaintenanceUse regenerator salt (Hard Temp CN2, 2–5%)
DocumentationCOA, MSDS, TDS included with every order

Bath Parameters & Process Steps

Controlled Bath Chemistry

CNO Content 31 – 40%

The cyanate level drives nitrogen diffusion. Regular testing keeps this within range for consistent case depth.

CO₃ Content 17 – 21%

Carbonate content builds as the bath ages. Maintained within range by periodic desludging and regenerator addition.

CN Content ≤ 1.0%

Cyanide is kept below 1% for process control and regulatory compliance. Aeration helps maintain this limit.

Bath Make-Up & Operation

1
Bath Make-Up

Fill a clean, dry pot to half volume with nitriding salt. Start the furnace at 580°C. After melting, top up to working level and reset to 565°C ± 5°C. Install the desludging tray and aerator.

2
Aeration

Start continuous aeration through a flow-control manometer. Air must be clean and oil-free. Aeration is maintained at all times — even when the bath is idle between production runs.

3
Bath Conditioning

Add 10 g of Potassium Sulphide (K₂S) per 100 kg of salt used. Continue aging with aeration for 24 hours. Check bath parameters, adjust with regenerator salt if required, and desludge.

4
Component Loading

Preheat components below 400°C for 15–30 minutes. Dip in the salt bath for 90–130 minutes. After dipping, drain molten salt over the pot and quench in water. Wash in clean overflowing water and dry.

5
Bath Replenishment

Replenish with fresh nitriding salt to make up drag-out loss. Add regenerator salt at 2–5% of nitriding salt weight. During normal operation add 2–3 g of K₂S per 100 kg salt per day.

6
Desludging

Desludge twice a week or as required. Stop aeration, allow bath to settle for 20 minutes, then remove the sludge tray. Resume aeration immediately after.

Key Benefits of the Process

Wear Resistance

The compound layer formed by nitrogen and carbon diffusion is significantly harder than the base metal — extending service life of moving components.

Anti-Seizure Properties

Nitrided surfaces resist metal-to-metal seizure under boundary lubrication conditions — critical for gears, cams and sliding components.

Minimal Distortion

Processing below the steel's transformation temperature means components stay in the ferritic phase. Dimensional changes are negligible compared to conventional quench-and-temper.

Faster Than Gas Nitriding

Liquid nitriding at 560°C–570°C achieves the required case depth in 90–130 minutes. Gas nitriding for equivalent case depths takes 20–80 hours.

Clean Component Finish

Components emerge with a dark, compact surface layer ready for use or light polishing. No scale, decarburisation or oxidation.

Works on Finished Parts

Low processing temperature allows nitriding of fully machined and dimensionally finished components without requiring grinding after treatment.

Typical Applications

Automotive Gears & Cams

Crankshafts, camshafts, rocker arms and gear components where wear resistance and anti-seizure behaviour determine service life.

Forging & Die Casting Dies

Hot forging dies and die-casting tool steels treated to resist heat checking, erosion and metal-to-metal seizure under high-pressure contact.

Extruder Screws & Barrels

Plastics and rubber extruder screws treated to resist abrasive wear from filled polymers — extending intervals between reconditioning.

Gearbox Components

Transmission gears, shift forks and splined shafts in industrial gearboxes requiring a hard, lubricious surface on a tough core.

Precision Steel Parts

Finished parts in alloy steels that need surface hardening without the distortion risk of quench-and-temper — such as jig and fixture components.

Job-Shop Heat Treatment

Commercial heat treatment facilities processing mixed orders of automotive, engineering and tooling components on a single liquid nitriding line.

Safety Precautions

Nitriding salt baths operate at high temperature and contain cyanate compounds. All standard molten salt handling precautions apply. Effluents must be treated as per applicable environmental regulations before discharge.

  • Wear goggles and face shield at all times near the open bath.
  • Use heat-resistant gloves and full protective clothing.
  • Ensure adequate ventilation or local exhaust extraction above the bath.
  • Keep components dry before loading — moisture causes violent spattering.
  • Treat effluents and spent salt per existing environmental laws before disposal.
  • Never allow temperature to drop below 540°C — bath may solidify and crack the pot.

Testing & Quality Control

Daily Hardness Check

Check surface hardness of treated components every day using a calibrated hardness tester.

Weekly Case Depth Check

Verify case depth by metallographic section once a week or as production requires.

Bath Parameter Testing

Test CNO, CO₃ and CN content regularly using rust-free M.S. rod samples at working temperature.

Bi-Weekly Desludging

Remove sludge tray at least twice weekly. Stop aeration 20 minutes before desludging to allow sludge to settle.

Related Products

Specialty Chemical

Activator

Barium-base carburising salt for liquid carburising of mild steel at 900°C–950°C.

View Details
Neutral Salt

SN-660 Neutral Salt

Pre-heating bath at 660°C–900°C used before hardening and austenitising.

View Details
Specialty Chemical

Regenerator

Anti-decarburization additive to restore bath neutrality and protect surface carbon.

View Details

Ready to order Nitriding Salt?

Ships from Shapar warehouse. COA, MSDS and TDS included. Same-day dispatch before 2 PM.