Heat Treatment Chemicals
CARBURISING & NITRIDING CHEMICALS:
|1.2.||Hard Temp H 402
||A carburising salt containing sodium cyanide and suitable activating agent. The carburising salt is capable of carburising mild steel and alloy case hardening steel upto depth of 2.5 mm. Working Range : 760° to 950° C|
|1.4.||Hard Temp F 750
||A salt specially developed for hardening high carbon steel files and medium or low carbon steel rasps. Slight decarburisation on the surfaces of the files can be removed by hardening in Hard Temp F 750. Working Range: 750° to 850° C.|
|1.5.||Hard Temp CN2
||A regenerator salt used in Hard Temp CN4 bath.|
|1.6.||Hard Temp CN4
||A specially designed base salt for nitriding of carbon steels, high speed steels and other type of alloy steels. Hard Temp CN2 salt is required to regenerate the bath. Working Range : 560° – 570° C.|
||An additive used in nitriding baths.|
NEUTRAL AND QUENCHING SALTS:
|2.1.||Hard Temp 660
||A neutral salt normally used with Hard Temp A 453 regenerator for hardening tool steel and selectively carburised steel. Also used for preparing initial melts of carburising salts Hard Temp H 402. The salt can be used for preheating hot die steels and high speed steels prior to hardening. Working Range: 660° to 900°C (upto 1000 0C if covered with Hard Temp E 452)|
|2.2.||Hard Temp 720
||A water-soluble neutral hardening salt normally used with Hard Temp A 453 regenerator for hardening various tool steels and selectively carburised steels. Sometimes it is also used with 1 – 10% sodium cyanide as a scale free heat treatment medium. Working Range: 720° to 900° C (upto 950° C if covered with Hard Temp E 452)|
|2.3.||Hard Temp 830
||The salt is used with Hard Temp A 453 regenerator for hardening chromium rust resisting steels B. S. En 36 A-D and B.S. En 57.Working Range: 830° to 1100° C|
|2.4.||Hard Temp 970
||Used for heating high-speed steels and hot work steels to the appropriate hardening temperature without scaling or decarburisation. Working Range: 970° to 1350° C.|
|2.5.||Hard Temp 495
||Used for quenching and secondary hardening of high-speed steels preferably where the temperature required is 500° to 540° C. Working Range: 495° to 700° C|
|2.6.||Hard Temp 540
||Specially developed for quenching high speed steels and hot work tool steels after heating in Hard Temp 970. It is also used for secondary hardening of high-speed tool steels and for tempering. Working Range: 540° to 700° C|
|2.7.||Hard Temp 660
||A neutral salt normally used with Hard Temp A 453 regenerator for hardening tool steel and selectively carburised steel. The salt can be used for preheating hot die steels and high speed steels prior to hardening. Working Range: 660° to 900°C (upto 1000°C if covered with Hard Temp E 452)|
|2.8.||Hard Temp F 666
||A neutral salt for use with Hard Temp F 750.|
TEMPERING AND HEAT TRANSFER SALTS:
|3.1.||Hard Temp 150
||Used for tempering after hardening. The salt may also be used as a quenching cum transformation bath when austempering jobs heated in muffle furnaces or salt baths. Working Range: 160° to 550° C|
|3.2.||Hard Temp 220
||Used for tempering after hardening. The salt may also be used as a quenching cum transformation bath when austempering jobs heated in muffle furnaces or salt baths. Working Range: 230° to 550° C|
|3.3.||Hard Temp 155
||A heat transfer salt for use in large chemical or oil cracking installation as a heating or cooling medium. Working Range: 155° to 540° C|
|3.4.||Hard Temp 330
||A special heat treatment salt used for specific purpose.|
|3.5.||Hard Temp 160
||A special tempering salt used after hardening. Working Range: 160° to 550° C|
MISCELLANEOUS SALTS AND CHEMICALS:
|4.1.||Hard Temp R 451
||A rectifier to be used along with neutral salts to keep the baths in nondecarburising condition.|
|4.2.||Hard Temp E 452
||Used to form a surface layer on carburising and certain neutral salt baths to prevent fumes, conserve bath strength, minimize fuel consumption and increase pot life.|
|4.3.||Hard Temp A 453
||A regenerator for use in neutral salt baths to keep the baths in nondecurburising condition.|
SALT BATH NITRIDING
Liquid Nitriding process involves enrichment of the Steel Surface basically with Nitrogen and very small amount of Carbon at a specified temperature range, by diffusion from Cyanide-free molten salt bath.
This thermo-chemical Transformation of the Steel surface enhances wear resistance, fatigue strength and anti-galling properties with least distortion and improves corrosion resistance.
It works very effectively for surface property enhancements on titanium, aluminum and chromium bearing steels as well as low alloy steels and stainless steels .
ENHANCEMENT OF PROPERTIES
Liquid nitriding increases wear resistance properties from 200% to 1000% , depending upon composition of base metal and fatigue strength by 20% to 100%.
PROCESS AND TECHNICAL DETAILS
Salt Bath Nitriding is performed at 560° - 570° C following necessary heat-treatment for core properties and finish machining. It ensures dimensional stability of processed parts and core properties which remain unchanged, provided heat treatment temperatures were higher than the liquid nitriding temperature, i.e. 560° - 570° C.
In liquid nitriding bath, which contains nitrogenous salts, nitrogen is released in a controlled and uniform manner at the interface of the work piece. Nitrogen by diffusion chemically combines with nitride –forming elements like aluminium, chromium and forms a tough ductile compound layer with high mechanical and chemical properties like hardness, wear resistance, anti-galling and resistance to corrosion.
Just adjacent and below the compound layer, another layer diffusion zone is formed. Diffusion zone consists of a solid solution of nitrogen in the base material. The diffusion zone contributes to substantial enhancement of fatigue strength. There is a simultaneous diffusion of carbon in a small amount which contributes to property enhancement combining with the base metal.
i) Liquid nitriding process is highly active, more efficient and time – saving compared to gas nitriding.
ii) After liquid salt bath nitriding the parts can be quenched in water, oil or cooled in air.
iii) The salt mixture is cyanide-free. So the waste / carry over dose not require treatment/ neutralization of toxic effect.
iv) The nitrided parts can be given a bright lustrous black finish by a supplementary operation.
v) The thermo-chemical transformation involves negligible dimension change / distortion.
Liquid nitriding has unique advantages – improvement of surface properties like wear resistance, anti-galling and chemical property as corrosion- resistance. Process time & energy cost being low, the process is cost saving. It is non-hazardous being cyanide-free.
Considering these, the process has wide application in automobile and other industries. The process is widely used for surface hardening of gears, cam shaft, spindles , slides and guides engine valves, bushes , flanges , aluminium Extrusion dies, hydraulic components, high speed steel tools, mining machineries, husking machines , pump bodies and many others.
It is an anti-carburising compound used while masking of selected areas component where carbon penetration is not desired. It works very effectively for the surfaces of the components where masking compound is applied during process of carburising
METHOD OF APPLICATION
Masking compound which can be easily applied on the chosen areas by brushing, dipping or by spraying. Normally a uniform layer obtainable by single coat application. Two coats of this compound is recommended where case depth for carburising is more.
TYPES OF MASKING COMPOUND
A) Non Aqueous Masking Compound.
This is a quick drying masking compound which is very stable and also effective in preventing carbon penetration on selected surfaces.
B) Water Based Masking Compound
This is a stable and eco-friendly masking compound easily applicable for prevention of carbon penetration as required.
1) Simple in application by brushing, dipping or spraying.
2) Quick drying in a well ventilated area.
3) Stable and eco-friendly in use.
4) No risk of cracking on uniform coating during process of heat treatment
5) Very much cost effective.