MICROSTRUCTURE AND CORRQSION PROPERTIES OF P/M FABRICATED MARTENSITIC STAINLESS STEEL CONTAINING NITROGEN

Abstract

Alloying of stainless steel with nitrogen is useful in increasing strength, wear

.and corrosion resistance and to decrease additional cost by alloying with nickel as one of the alloying elements, which is considered as a most expensive alloying element. Nitrogen is difficult to be dissolved in stainless steel by conventional methods. The powder of martensitic stainless steel containing 0.5% nitrogen was prepared by plasma rotating electrode process (PREP) and

consolidated by Hot Isostatic pressing process (HIP). In this work specimens of the alloy were solution treated at 1050°C for two hours and water quenched, some of specimens tempered at 370°C, 400°C, 500°C and 600°C for two hours then cooled in the air. The hard ness of the solution treated and tempered specimens were measured. The results showed the highest hardness was obtained for solution treated specimens and the lowest hardness value for specimens tempered at 500°C.The corrosion behavior of the solution treated specimens and solution treated followed by tempering specimens were studied by potentiodynamic teclmique in two different concentration of sodiLUn chloride solutions, namely 1% and 3% in stagnant and stirring conditions in 1%NaCl. The stirring was at 600 rpm, 900 rpm, and 1200 rpm. The results showed that the highest corrosion rates were for the specimens tempered at 500°C.