Quenching Medium
A quenching medium is a coolant that increases the heat dissipation rate at the workpiece surface, thus preventing structural hardening.
Physical-Chemical Mechanism of Action
Quenching media bind oxygen and prevent the metal from cooling too fast. This slows down crystal growth and prevents the formation of hard structures like martensite.
Metallurgical Relevance & Risks in Welding
Without quenching media, the metal can cool too fast, leading to glass-hard martensite. This can cause cracks and hot cracking. An insufficient quenching medium, on the other hand, can lead to slow cooling, resulting in a softer structure and lower toughness.
Workshop Practice & Action Instructions
Use quenching media in the correct amount, depending on the metal type and welding process. For high-carbon steel (e.g., HSS), a strong quenching medium like silicon or potassium chloride is necessary. Watch the temperature curve and cool the metal continuously to ensure uniform cooling.