Fracture Analysis of Case Hardening in Kingpins Parts

Kingpin parts are the critical product for heavy vehicles and are generally made of 20MnCr5 steel. A kingpin is a heavy metal cylindrical pin that is located underneath the front end of the trailer. The kingpin is the mechanism on the trailer that locks it to a road tractor. The parts in this study have undergone to case hardening heat treatment after the rough machining operation. During the operation in the assembly line, cracks have been shown on the parts surface. In this study, kingpin parts are examined with Scanning Electron Microscopy (SEM) analysis, hardness and %C potential analysis in order to determine the potential causes of crack formations. It is shown that, heat treatment of the parts is not homogeneously distributed and therefore fractures occur. The exact outcome of the fracture could not be determined. Under the scanning electron microscope, it becomes clear that it is a crack. There are no signs of hydrogen embrittlement. With the present structure, it is to be expected that even a low dynamic load can lead to breakage. As a result, investigations suggest that the parts have exposed to incorrect heat treatment parameters.

___

  • Jaroslav, M. (2003). Finite element analysis and simulation of quenching and other heat treatment processes. Computational Materials Science, 27, 313-332.
  • Ono, T., & Allaire, R. A. (2000). Fracture analysis, a basic tool to solve breakage issues. Taiwan FPD Expo 2000.
  • Garcia, C., Martin, F., De Tiedra, P., Heredero, J. A., & Aparicio, M. L. (2001). Effects of prior cold work and sensitization heat treatment on chloride stress corrosion cracking in type 304 stainless steels. Corrosion science, 43(8), 1519-1539.
  • Goldstein, J. I., Newbury, D. E., Michael, J. R., Ritchie, N. W., Scott, J. H. J., & Joy, D. C. (2017). Scanning electron microscopy and X-ray microanalysis. Springer.
  • Budinski, K. G. (1988). Surface Engineering for Wear Resistance.(Retroactive Coverage). Prentice-Hall, Inc, Englewood Cliffs, New Jersey 07632, United States
  • Krauss, G. (1990). Steels: heat treatment and processing principles. ASM International, 497.
  • Drozda, T., & Wick, C. (1985). Tool and Manufacturing Engineers Handbook: Materials, Finishing and Coating (Vol. 3). Society of Manufacturing Engineers.
  • Grube, W. L., & Gay, J. G. (1978). High-rate carburizing in a glow-discharge methane plasma. Metallurgical Transactions A, 9(10), 1421-1429.
  • Akiniwa, Y., Stanzl-Tschegg, S., Mayer, H., Wakita, M., & Tanaka, K. (2008). Fatigue strength of spring steel under axial and torsional loading in the very high cycle regime. International Journal of Fatigue, 30(12), 2057-2063.
  • Meyers, M. A., & Chawla, K. K. (2008). Mechanical behavior of materials. Cambridge university press.
  • Shipley, R. J., Becker, W. T., & ASM, H. V. (2002). Failure analysis and prevention. ASM handbook, 11, 508.
  • ASTM E 350 (2000). Standard Test Methods for Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and Wrought Iron, 2000.
  • SAE J 404 Standard, Chemical Compositions of SAE Alloy Steels (2009). International Journal of Engineering Research & Science (IJOER), 2(6) June-, p. 109
  • ASTM E 112 (2006) Standard Test Methods for Determining Average Grain Size
  • ASTM A 370 (2007). Standard Test Methods and Definitions for Mechanical Testing of Steel Products.
  • Hull, D. (1999). Fractography: observing, measuring and interpreting fracture surface topography. Cambridge University Press.
  • Vargas-Arista, B., Teran-Guillen, J., Solis, J., García-Cerecero, G., & Martínez-Madrid, M. (2013). Normalizing effect on fatigue crack propagation at the heat-affected zone of AISI 4140 steel shielded metal arc weldings. Materials Research, 16(4), 722-778.
  • Shoffner, B. W. (2008). Development and validation of a finite element analysis model used to analyze coupling reactions between a tractor’s fifthwheel and a semitrailer’s kingpin.
  • Dieter, G. E., & Bacon, D. J. (1976). Mechanical metallurgy (Vol. 3). New York: McGraw-hill.
  • Gao, F. M., & Gao, L. H. (2010). Microscopic models of hardness. Journal of superhard materials, 32(3), 148-166.