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IJMERR 2024 Vol.13(1): 175-183
doi: 10.18178/ijmerr.13.1.175-183

Failure Analysis of S55C Medium Carbon Steel for the Pickup Crankshaft

Bundit Inseemeesak 1 and Visanu Boonmag 2,*
1. Automotive Manufacturing Engineering, Faculty of Engineering and Technology, Panyapiwat Institute of Management, Bangkok, Thailand
2. Department of Mechanical Engineering, Faculty of Engineering, Thonburi University, Bangkok, Thailand
Email: banditins@pim.ac.th (B.I.); visanu396@yahoo.com (V.B.)
*Corresponding author

Manuscript received June 2, 2023; revised August 2, 2023; accepted August 31, 2023; published February 24, 2024.

Abstract—There have been reports from service centers of important problems of a diesel engine crankshaft in mini trucks. All crankshafts crack from the same region, the fracture occurred in the first crankpin of the crankshaft. The crankshaft is made from JIS-S55C hardened medium carbon steel. A series of experiments including chemical analysis, macro and microstructural analysis, mechanical properties test, and numerical stress analysis. The results of fracture surface of this crankshaft were cause by fatigue with the detection of beach marks, ratchet marks, river marks, cleavage fracture and fatigue striations which these results indicate that the fracture mode of brittle fracture. The microstructure is composed of perlite-ferrite on the outer surface showed some coating nitriding layers, most hard coating is not found, the hardness test revealed an uneven hardness distribution, the maximum hardness on the center of the shaft measuring 309 HV, which is more than compared to the outer surface is 259 HV for these applications. It was found that the hardness value was abnormal. This is consistent with the experimental results of the surface microstructure which showed some coating layers, while the hard coating is not found. Besides, the numerical results also revealed that the first crankpin fillet was the most vulnerable to breakage, which is consistent with the mechanical experimental results. Finally, the summary analysis results are consistent with the hypothesis of this research and as an information for a prevent such failures crankshaft in the future.

Keywords—pickup trucks, first crankpin, fatigue, nitriding layers, numerical stress analysis

Cite: Bundit Inseemeesak and Visanu Boonmag, "Failure Analysis of S55C Medium Carbon Steel for the Pickup Crankshaft," International Journal of Mechanical Engineering and Robotics Research, Vol. 13, No. 1, pp. 175-183, 2024.

Copyright © 2024 by the authors. This is an open access article distributed under the Creative Commons Attribution License (CC BY-NC-ND 4.0), which permits use, distribution and reproduction in any medium, provided that the article is properly cited, the use is non-commercial and no modifications or adaptations are made.