HENRY GRANJON PRIZE COMPETITION 2006 Winner, Category C 'Design and structural integrity' NON-DESTRUCTIVE DETERMINATION OF INTERSTITIAL NITROGEN CONTENT IN AUSTENITIC STAINLESS STEEL WELD METAL UTILIZING THERMOELECTRIC POWER

摘要

Electronic properties of an alloy correlate directly to its microstructure. The thermoelectric power coefficient has been determined in this investigation to be a rapid and accurate measurement, which can be utilized for microstructural assessment and correlated to achieve maximum material performance of structural alloys. In high nitrogen-strengthened stainless steel welds, nitrogen partitions into solid solution nitrogen and nitrides during the welding thermal cycle. The formation of nitrides results in a degradation of mechanical properties and corrosion resistance. Thermoelectric power measurements offer a means to assess the weld interstitial nitrogen content allowing for a better correlation between nitrogen content and weld metal microstructure and properties. The thermoelectric power coefficient has been measured on plasma gas-tungsten arc welds on nitrogen-strengthened austenitic stainless steel alloy 1.4565, which has been interstitially strengthened with nitrogen for enhancement in mechanical properties and corrosion resistance.