Advanced Materials & Processes

FEB 2015

Covers developments in engineering materials selection, processing, fabrication, testing/characterization, materials engineering trends, and emerging technologies, industrial and consumer applications, as well as business and management trends

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A D V A N C E D M A T E R I A L S & P R O C E S S E S | F E B R U A R Y 2 0 1 5 2 7 quantitative average, which was based on 25 random measurements around the periphery. If it was assumed that the vi- sual estimate of the greatest MAD around the bar periphery would be deeper than the mean MAD of 25 randomly chosen lo- cations, then the actual result would be rather surprising. ConClusions Decarburization of steel parts is a serious problem as the weaker surface layer reduces wear resistance, enabling fatigue failures to occur more easily. A simple screening test was discussed, which can be used for certain shapes and high production runs. If the sur- face hardness is below some predeter- mined limit, which varies with grade, then a microstructural examination is required. Chemical analysis of carbon on incremental turnings (or millings) can be performed, although this is more applicable to research than pro- duction. Metallographic rating of de- carburization depth requires properly prepared specimens with good edge retention. This can easily be achieved with modern equipment and is reason- ably fast. Qualitative measurements of the free-ferrite depth (when present) and the maximum afected depth of de- carburization are usually adequate. But such measurements are subject to bias and the reproducibility is not as good as when quantitative measurements are made using at least 25 randomly select- ed locations around the bar periphery. Microindentation hardness traverses are excellent for defining the MAD. The FFD is easily observed by light micros- copy and adequate inspection of the periphery is needed to detect the deep- est amount present. ~AM&P For more information: George F. Vander Voort is a consultant for Struers Inc., 24766 Detroit Rd., Cleveland, OH 44145, 847.623.7648, georgevandervoort@yahoo. com, References 1. A. Bramley and K.F. Allen, The Loss of Carbon from Iron and Steel When Heated in Decarburizing Gases, Engineering (Lon- don), Vol 133, p 92-94, 123-126, 229-231, and 305-306, 1932. 2. J.K. Stanley, Steel Carburization and De- carburization – A Theoretical Analysis, Iron Age, Vol 151, p 31-39 and 49-55, 1943. 3. F.E. Purkert, Prevention of Decarburiza- tion in Annealing of High Carbon Steel, J. Heat Treating, Vol 2, p 225-231, 1982. 4. H.W. Grasshoff, et al., Effect of Different Dew Points of the Heat Treating Atmo- sphere on the Skin Decarburization of Heat-Treatable Steels, Stahl ünd Eisen, Vol 89(3), p 119-128, 1969. 5. G.E. Wieland and E.M. Rudzki, Effects of Furnace Design and Operating Parameters on the Decarburization of Steel, Metal Progress, p 40-46, February 1979. 6. R. Rolls, Heating in the Drop Forge: Formation and Properties of Scales on Iron-Base Alloys, Metal Forming, Vol 34, p 69-74, 1967. 7. K. Sachs and C.W. Tuck, Surface Oxida- tion of Steel in Industrial Furnaces, ISI SR 111, London, p 1-17, 1968. 8. E. Schuermann, et al., Decarburization and Scale Formation, Wire Journal, Vol 7, p 155-164, 1974. FREE PERIODIC BEER GLASS! Get a FREE Periodic Beer Glass when you ask for your no-obligation training assessment. Contact Ravi Dodeja for complete details. Phone: 440.338.5414 Email: CUSTOMIZED TRAINING COMES TO YOU ASM's Customized On-Site Training brings personalized courses to your facility that will elevate performance and increase production. Features include: • A productive use of your staff's time with convenient access to world-class instructors at your facility • Information that is immediately applicable to • Programs customized to fit your needs your business after the course is completed REGISTER NOW AT ASMINTERNATIONAL.ORG/LEARNING/COST g

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