Discussion on "Nitralloy steel and nitriding" at the Glasgow Section of the Institution

MR. R. J. TAYLOR: I am interested from the point of view of corrosion of nitralloy articles. The author mentioned that these articles had been used for superheated steam valves. I take it he referred to seats, discs, heads, lids, or spindles. One of the great difficulties in components for steam manufacture is where one part is pressed into another part and that other part is not of the same alloy or construction as the component which is pressed in. I can imagine a situation such as a nitralloy seat being pressed into a steel casting. I would ask if he has any experience of what happens if the seat was pressed into, say, a cast steel valve casing (the valve working in superheat at 840 degrees C.) and the plant was shut down suddenly and allowed to cool? Does he think the seat would cool quicker than the body and that a shrinkage would take place and it would become loose?