Corrosion of Railroad Hopper Car Body Sheets

The corrosion of railroad hopper car body sheets is dependent upon the character of the lading, the atmospheric conditions to which the car is subjected, the design of the car, and the composition of the body sheets. Information obtained from a large number of tests of various materials exposed in different kinds of atmospheres has been correlated with data obtained from service tests of a few of these materials in railroad hopper cars. On the basis of assigned ratings of 1 for carbon steel, it has been found that copper steel has an atmospheric corrosion resistance rating of 2 and a performance rating of 1⅓ to 1½ in general service. A C-Mn-Cu Steel which also has an atmospheric corrosion resistance rating of 2, and a strength level somewhat higher than that of copper steel, is slightly superior to copper steel in hopper ear service. The service performance of a high strength steel which has an atmospheric corrosion resistance rating of 5+ and a strength level equal to that of the C-Mn-Cu Steel, is considerably better than that of copper steel. Examination of hopper car bodies constructed of carbon steel, copper steel and high strength steels has shown that failures in the sheets generally occur in areas where lap joints or ledges permit accumulation of moisture, dirt and fines, and in areas adjacent to stiffening members. The results of these investigations indicate that in order to obtain the maximum service from materials used for hopper car bodies, the design of the car must be considered simultaneously with the composition of the sheet material.