Effect of Simple or Combined Addition of Mo, Si and Cu on Mechanical Properties and Corrosion Resistance of 30Ni-20Cr Stainless Steels

Study on 30Ni-20Cr stainless steels. II

Abstract

Effect of simple, or combined addition of Mo, Si and Cu, on the properties of 30Ni-20Cr stainless was investigated by hardness, tensile, microscopic and corrosion tests.
The corrosion tests were carried out with specimens in boiling 5 wt %H2SO4 and 1 wt % HC1 for 6 hours.
The following results were obtained.
(1) Against boiling in 5 wt % H₂SO₄ and 1 wt % HCl, 30Ni-20Cr stainless steels containing 3% Mo showed an appreciable corrosion resistance and the same steel containing 3 % Mo+ 3% Cu showed a superior corrosion resistance. Moreover addition of 3-3. 5% Si improved mechanical properties in some degree.
(2) A decrease in elongation and Charpy impact value probably may be attributed to the amount, form and distribution of a metallic compound (Fe₂Mo), the amount of which has been increased mainly by addition of Mo.