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ALTHOUGH average car life has jumped in 30 years from 6½ to 13½ years, improvements in service life of body structures have not kept pace with increased durability of engines and other mechanical parts. Hence the growing interest in improving corrosion resistance of the sheet steels used in auto bodies. This paper reports results obtained in cyclic humidity accelerated corrosion tests aimed at finding a cheap, easily formed sheet steel with better resistance against the sheltered corrosion which causes the most serious body damage. The test produces in 20 days the same kind of non-protective rust formed in years of outdoor exposure. Since high-carbon steels, shown in the tests to be the most potent corrosion reducers, cannot be used in auto bodies because of their poor forming characteristics, efforts are now being directed toward finding a combination of elements that will produce the same results without a cost or forming penalty.

RELATIONSHIP of the factors of lubricant and engine design which affect wear of cams, lifters, rocker arms, and rocker shafts is discussed in this paper, which is part of the Symposium on Cam and Tappet Wear. To reproduce service failures of valve-train parts in the laboratory in a short time, special tests procedures and certain engine modifications were devised for this study. Results of these laboratory tests, which agree well with data obtained in actual service, are presented here.

DATA from several fatigue-test programs are examined in this paper for corroboration of basic factors which have been proposed for predicting more accurately the fatigue strength of full-scale steel members. Important among these factors are hardness, service loading, range of stress, and sharpness of the stress gradient at the critical zone. Although the type of steel is often regarded as a primary factor, its hardness may be more basic, as it correlates better with endurance limit than other physical tests. Test results show that this hardness-strength relationship is useful in evaluating the effect of surface treatments on strength improvement in soft and medium-hardness steels.

RESULTS of an investigation into the effect of shot-peening variables and the resulting residual stresses on fatigue life are reported in this paper. Leaf springs were the simple specimens heat-treated, cold worked, and tested in this study. Some of the conclusions reached are: 1. There is a minimum shot velocity for each shot size to obtain best fatigue life, and this value is much lower than that normally used. 2. Exposure time for this type of shot-peened specimen beyond some minimum value is wasteful and costly. 3. Shot size has little influence on fatigue life for these specimens. 4. Shot peening specimens while under tensile strain greatly increases fatigue life at 200,000 psi nominal stress over that of nonpeened or strain-free-peened specimens. 5. Shot peening these specimens gave residual compressive stresses 50% of yield strength, and these stresses can be increased to more than 50% by strain peening. 6.

EXPERIMENTAL analyses of residual stresses as related to fatigue properties and to the surface failure known as spalling are discussed in this paper. How those processing operations such as heat-treatment, machining, grinding and straightening contribute the factors causing residual stresses and what are the practical methods of measuring these stresses are also described here.

CLADDING of steel parts or assemblies with aluminum, through the use of a recently developed process which has been in commercial operation for two years, is described in this paper. Successful plant and field experience indicates that it can be applied at room and elevated temperatures in various types of atmospheres. This new process was originally designed to offer corrosion resistance caused by the collection of leaded fuel gas condensates in exhaust systems, and for other parts requiring high-temperature oxidation resistance up to 1600 F. However, it has since been used in a wide variety of applications.