Hardening of steel components is one of the most commonly practiced heat treatment operations in the steel industry. Quenching is a process whereby a steel component heated to a given elevated temperature is rapidly cooled by immersion in a quench bath containing compositions such as air, water, brines, oils and polymer solutions.
Water and brines produce very rapid cooling rate and are not suitable for quenching many types of steel. Because they produce excessive strains which warp and crack the steel.
Hydrocarbon oils produce a relatively slow rate of cooling, which is required to produce desired physical properties such as ductility but prevent developments of desired hardness. In additions to, oils are expensive, have low flash points which create a risk of fire and leave undesirable film on the components which produces smoke and fume during quenching and tempering.
Low cost aqueous solutions of organic polymers have been developed to cool metals at rates intermediate between water and oil to obtain desirable physical and mechanical properties.
Vetra Company, as the first provider of polymer quenchants in IRAN, has produced varied types of water-soluble polymers with the commercial name of “ AQUENCH” by a group of engineers and specialists.
These products are so suitable and cost-effective tailored to the needs of heat treatment industries for materials and various alloys and has been able to produce an effective step towards achieving higher-quality for parts and materials as well as better environmental conditions of heat treatment shops and area.
These products are based on various molecular structures and can be used for different types of steel, cast iron; aluminum and copper.
The most important ones are:
Aquench PK150, Aquench PS150, Aquench PS200, Aquench PG150, Aquench PC160
The main advantages of these polymer quenchants:
- Elimination of fire hazard: these products are nonflammable and eliminate the need for protection equipment or extinguishing systems.
- Cleaner, safer working environment: no smoke and fumes during quenching and tempering.
- Flexibility of quenching speed: by varying the concentration, temperature and agitation of polymer solutions; it is possible achieve a range of cooling rates.
- Reduction of stresses and distortion: uniform polymer film around the components, reduces thermal gradients and residual stresses, therefore, give substantial reduction in distortion.
- Elimination of soft spots: by producing a uniform polymer film around the components, soft spot problems will be eliminate.
- Reduced cost: depending upon the type of polymer and concentration required, Because of lower viscosities and drag-out, the cost of diluted polymer quenchants will considerably be lower than those of quenching oils. On the other hand, fire insurance premiums will be eliminating.
- Easier cleaning: residual films of polymer, unlike the oils, will not char but will decompose fully at high temperatures to form Water vapor and oxides of Carbon. For low temperature tempering or aging treatments where the polymer may not decompose completely, the residual film can be removed by simple washing in plain water.
- Reduce temperature rise during quenching: polymer quenchant solutions have almost twice the specific heat capacity of quenching oils. Therefore, for a given charge weight, the temperature rise during quenching will be approximately halved.