The most commonly used industrial thermocouples are identified for convenience by type letters. The commonly used base metal thermocouples are types E, J, K, and T. Of these, J and K are probably the most usual ones.
Many metals and alloys are suitable to be used in thermocouples as the thermoelectric effect happens when two dissimilar materials are put in contact forming a thermal junction. Thermocouple materials are chosen according to maximum sensibility over the operating range, long-term, cost, and compatibility with the instrumentation.
Download the Duro-Sense Base Metal Thermocouples Catalog Here