Fracture Analysis of Case Hardening in Kingpins Parts

Tuğrul Soyusi̇nmez,Tolga Palanduz,Onur Ertuğrul,Oğuzcan Güzeli̇pek

doi:10.26701/ems.884610

Abstract

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.

Highlights

The n-trailer system is a unlike a flat system, who is flat outputs are the Cartesian coordinates of the middle point of last trailer’s rear axle
Mobile robots with trailers are flat systems as soon as the trailers are hitched to the middle point of the axle of the previous ones
In order to understand the reasons of the kingpin’s failure, the broken failure areas were examined by Scanning Electron Microscopy (SEM)

Summary

INTRODUCTION

The n-trailer system is a unlike a flat system, who is flat (or linearizing) outputs are the Cartesian coordinates of the middle point of last trailer’s rear axle. The finite element method (FEM) makes it possible to estimate the residual stresses in components during heating and quenching to determine the relationship between process parameters and the mechanical properties of the material being processed [6]. Rifle faces, engine crankshafts can be shown as examples of parts that have been processed In these cases, the surface may be hardened selectively, leaving the center of the part in its original tough state [7,8]. The environmental factors include the processes of forming by cold plastic deformation and seam welding The latter justifies that there is a growing interest in knowing the effect that prior to cold work and sensitization treatment have on the stress corrosion cracking behavior of these types of materials [9,10].

MATERIAL AND METHODS

RESULTS AND DISCUSSION

CONCLUSIONS