Gopal & Fomra Nitriding

Non pollutive sulfur accelerated Nitriding and nitrocarburising process.

Nitriding process solves problems of wear, scuff seizure, fatigue and corrosion of ferrous meterials like steels and cast irons.

Nitriding process helps you to bring down warranty claims and customer satisfaction.

Nitriding also greatly reduces costs because of short treatment times. Nitriding is applied to fully finished and ground componentsas it is distortion free. It can hence be advantageously utilised to replace cyaniding, carboNitriding, gas Nitriding and carburising.

Materials Treated By Us

CARBON STEELS ■ ALLOY STEELS ■ HIGH SPEED STEELS ■ STAINLESS STEELS ■ CAST IRONS INCLUDING SG IRONS

The Process

Temperature of operation 560 ° + 10 °C

There are three separate salts needed for operation of Nitriding

• Base salt NC4 used for making up new baths and also to maintain the working bath at a constant level by means of periodic additions.
• Regenerator salt NC2 used to regenerate the bath and maintain & constant Nitriding potential.
• Potassium sulphide(K2S)added regularly in very small quantities to maintain the non pollutive nature of the bath and improve the metallurgical properties of parts treated in it.

Properties of Nitriding Treated Parts

Increase in Nitriding Hardness the compound zone and the less is its thickness.

The higher the carbon and alloy contents of the surfaces treated the higher is the hardness of the surface layer.

Relation between hardness & depth of nitrogen penetration of steels treated at 570'C for 2 hours.

• EN8 (SAE 1038)
• EN19 (SAE 4140)
• H 11 Die Steel

Metallography of Nitriding Layers

Nitriding process produces a combination of a very hard compound zone of epsilon and the diffusion zone. The higher the carbon and alloy content of the substrate, the more compact is the compound zone and the less is its thickness. The sulfur produces a unique porous surface layer.

Decrease In Frictional Power Loss

Nitriding reduces coefficient of friction of treated surfaces. This results in reduced frictional power loss under identical conditions and contributes to increased fuel economy.

Increase In Wear Resistance

Resistance to adhesive and abrasive wear is increased enorously by Nitriding process. The wear resistance is better than other treatment processes like phosphating, gas Nitriding case hardening etc. as given in Fig. 2

Increase In Scuffing And Seizure Resistance

The sulfur compounds present in the surface layers inhibit 'metal to metal' welding and facilitates 'running-in'. Hence it completely eliminates problems of scuff and seizure (Fig. 3)

Figure 3

Increase in Fatigue Resistance

Nitriding gives rise to residual compressive stresses on the Nitriding which increases the fatigue strength of treated components. (Fig. 4)

NUMBER OF REVOLUTIONS, log scale Amaler tests with 20 kg load on 0.15% C steel test pieces subjected to various treatments using SAE 30 oil as lubricant.

Dimensional Change

Nitriding treatment gives rise to a uniform growth of components, this being independent of the shape and position in the bath during treatment, but differing in magnitude depending on the composition of the material (Chart-2)

Prerequisites For Components To Be Treated By Us

The component to be treated by Nitriding should have been earlier stress relieved or tempered at a minimum temperature of 580C for 3 hours minimum.

Typical Components Treated By US

• Crankshafts
• Camshafts
• Cylinder liners
• Valves and Valve guides
• Timing gears & spockets
• Rocker Arm Shafts
• Bearing cages
• Flanges
• Bushes
• Shafts & spindles
• Slides & guides
• Cylinder blocks
• Front fork tubes
• Railways components
• Plastic machinery screws & barrels
• Hydraulic components Mining machinery components
• Aluminum extrusion dies
• Metal working tools
• High speed steel eating tools
• Defence Components
• All ferrous materials & its alloys.

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