Brine Quenching
Brine quenching, or salt bath quenching, has the fastest cooling rate. Brine is a solution of water and salt. Salts have been used in the quenching process for many of years. They have a wide operating temperature range, and can minimize problems involving iron and steel parts. This is great for materials that have low harden ability.
Salt or brine quenching has many advantages over oil quenching. Nonflammable salt may not create fire hazards unlike oil. Salt can be washed off and cleaned easily with water. Washing oil requires specific cleaners and equipment. Salt can sometime be recovered and reused, whereas oil, is harder to reuse. Salt baths can be better controlled then oil baths. Temperatures, water content, and agitation are easier to control. Salt poses greater quenching benefits than oil.
Quenching salts can come in a mixture of elements. The construction of slat can vary by amounts of nitrates, sodium, potassium, and nitrites. Because the different chemical composition the melting points can vary from 275-500°F. Salts can be granular or crystalline form only. These structures are compacted into a briquette or flake form.
Salt system are low maintenance and can handle contaminates well. Salt baths can last for many years by either add new salt or recovering old salt. Contaminants like metallic debris can cause some problems in the quenching tank. Prats and cast of carbonates that form during quenching can cause sludge. This sludge can lower the cooling rate of the saline bath. Cleaning is key.
