4 key factors in choosing PAG quenchant

The Principle of Quenching:

Quenching is a heat treatment process that involves heating a metal to above its critical temperature to form austenite, and then rapidly cooling it at a rate exceeding the critical cooling rate. This process transform the metal's microstructure into high-hardness martensite, ‌importantly‌ increasing its hardness, strength, and wear resistance.

Available Quenching Media:

 

Water quenching offers the fastest cooling rate more oil quenching, it can result in higher hardness, but it is prone to cracking. Oil quenching can also offers a more moderate cooling rate, resulting in better toughness and reducing the risk of cracking, but it is more expensive and poses greater safety hazards.

Salt bath quenching has a short process cycle but suffers from poor anti-corrosion performance. Aqueous polymer quenchants are more widely used due to their excellent thermal stability and cooling characteristics.

Among them, PAG (Polyalkylene Glycol) quenchant is the most widely used quenching medium globally. It is extensively applied in the heat treatment of aluminum alloys and steel. As an eco-friendly quenching polymer, it can serve as a substitute for traditional oil-based quenchants. CHORUS offers a variety of high-molecular PAG polymer quenchant formulations, including 75W-18000, 75W-23000, 75W-50000, 75W-70000, and more. For further details, please consult: https://www.cnlubricantadditive.com/polymer/polyether-pag/polyalkylene-glycol-pag-for-quenchants.html

Four Key Factors of PAG Aqueous Solutions as Quenching Agents

 

Inverse Solubility (Cloud Point Effect)

 

 

PAG-based quenchants are a widely used type of modern quenching media characterized by inverse solubility. Their cooling rate is adjustable and falls between that of brine and cold oil.The concentration can be easily measured, making it suitable for a wide variety of steel grades.

PAG has more advantages, including a long service life, low consumption (approximately 40% of traditional oil quenching), non-toxicity, smoke-free operation, non-flammability, non-corrosiveness, and excellent aging resistance. It insure uniform hardening while significantly reducing the tendency for cracking and quenching distortion.

 

Concentration Control

 

The stability of PAG concentration is a critical factor affecting both the cooling stability of the fluid and the quality of the important products.

A higher PAG concentration effect in a thicker polymer film, which slows the heat transfer between the workpiece and the medium; so, the required cooling conditions can be controlled by adjusting the concentration.

e.g., The higher concentrations PAG can be used with high hardenability, small sizes, complex shapes, or those prone to distortion and cracking should , and vice versa.Temperature Control

 

Temperature Control

 

The cooling characteristics of PAG quenchants are very sensitive to temperature. Because of their reversible solubility, PAG will precipitate out of the solution when the temperature exceeds 70°C.In effect‌, the operating temperature should be strictly controlled, commonly maintained at or below 55°C

Agitation Requirements

PAG quenching, Propeller agitators or jet pumps should be used for circulation, while compressed air should be avoided. Insufficient agitation can lead to quenching defects, whereas excessive agitation may disrupt the PAG film and compromise the cooling effect. If the quenching fluid remains idle for an extended period, regular circulation/agitation is necessary to prevent the growth of anaerobic bacteria.

 

Chorus supplies a comprehensive series of PAG polymers. Our PAG water-soluble quenchants have earned unanimous praise from international customers for their high quality and superior performance. Beyond providing products, we also offer professional technical solutions. For inquiries, please visit: https://www.cnlubricantadditive.com/polymer/polyether-pag/