ME 4763 Chapter : Fall 2004
Document Summary
Describe the effects of oxygen on the corrosion of (a) regular steel used in chemical environments and (b) on stainless steels in similar environs. Oxygen tends to increase the corrosion of regular steels through oxidizing the steel. The reactions can cause the steel to rust. Stainless steels have a protective passive layer (usually chromium oxide). These do not corrode as easily as the regular steels. (or) Describe corrosion due to oxygen deficiency in differential oxygen or aeration cells. Give one example for its occurrence in a real case. Sensitization refers to the precipitation of carbides at the grain boundaries in stainless steel. Causes the material to become weaker and susceptible to intergranular corrosion. Occurs because the grain boundaries become susceptible to corrosion. (or) Occurs in brasses when in prolonged contact with waters high in oxygen and carbon dioxide. Brass with more that 15% zinc are most susceptible. Add 1% tin to the alloy to reduce plug dezincification.
