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ML00120 - Jun.2018

Ductile Rupture of a Carbon Steel Eye Bolt

Micrography of a longitudinal section of the bolt at the bottom of the thread fillet, presenting a plastically deformed ferritic pearlitic structure in a very small extension from the surface (about 0.1mm). This analysis was conducted in a position far from the failure and the structure was created by the cold forming process to manufacture the thread.

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of a of the at the bottom of the thread fillet, presenting a plastically deformed in a very small extension from the surface (about 0.1mm). This analysis was conducted in a position far from the failure and the was created by the cold forming process to manufacture the thread.
M

Material

Low Carbon Steel
  • ISO 898-1 class 5.6
  • UNS G10200
Ds

Description

The bumper eye , non shouldered, fractured in a ductile way due to at the position where the was tight. The bolt presented a , grains slightly elongated that are characeristic of a cold forming process (responsible for the high Yield Strenght), and the thread was manufactured by a cold rolled process. The overloading created in the bottom of adjacent thread fillets, by ductile microvoid formation.

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Chemistry (% in weight)

Product Analysis

0.22C; 0.18Si; 0.63Mn; 0.021P; 0.016S; 0.04Cr; 0.09Cu.

Associated Images
Detailed aspect of the eye bolt fracture position, with strong plastic deformation indicating ductile overloading. The red marks in the thread surface of the bolt (in the left side of the image) correspond to the position where the nut was tight. Thread fillets adjacent to the fracture presented secondary cracks.
1125
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Aspect Before AnalysisDf - Ductile Fracture
Macrography of a longitudinal section of the eye bolt, presenting the fracture in the top of the figure and the threads in the left side of the figure. Details of the fracture of the first thread fillet below the fracture are presented in the next figures.
225
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - NItal Etched MacroDf - Longitudinal Section
Micrography as polished of the longitudinal section of the bolt at the fracture position. The fracture (top of the figure) is rough, characteristic of a ductile fracture.
196
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - As polished micrographyDf - Fracture
Micrography as polished of the longitudinal section of the bolt at the first thread fillet below the fracture, presenting a cracking at the bottom of the fillet.
194
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - NItal Etched MacroDf - Crack
Apect of the 1/2" ND bumper eye bolt that was fractured (in the left side of the figure) in the position where the nut was tight.
192
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Aspect Before AnalysisDf - General View
Micrography of a longitudinal section of the bolt in the center of the thickness, presenting a ferritic pearlitic structure with elongated grains due to the forming process, without later heat treatment.
173
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrographic detail of the ferritic pearlitic structure, with grains sligthly elongated.
157
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrography of a longitudinal section of the bolt at the bottom of the thread fillet, presenting a plastically deformed ferritic pearlitic structure in a very small extension from the surface (about 0.1mm). This analysis was conducted in a position far from the failure and the structure was created by the cold forming process to manufacture the thread.
152
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Nital Etched Micrography by OMDf - Rolled Thread
Micrographic detail of a longitudinal section of the bolt at the bottom of the thread fillet, presenting a plastically deformed ferritic pearlitic structure. This analysis was conducted far from the failure and the structure was created by the cold forming process to manufacture the thread.
147
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Nital Etched Micrography by OMDf - Strain Hardened
Micrography of a longitudinal section of the bolt at the thread fillet adjacent to the fracture, presenting a ductile cracking from the bottom of the fillet, propagating with a strong plastic deformation. The deformation lines of the cold formed process (thread cold rolling) are also deformed by the cracking propagation.
141
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Nital Etched Micrography by OMDf - Ductile Crack
Micrographic detail of a longitudinal section of the bolt at the bottom of the thread fillet adjacent to the fracture, presenting a ductile cracking propagating with a plastic deformation. The deformation lines of the cold formed process are also deformed by the cracking propagation and there are some other small secondary cracks at 90° from the principal cracking.
133
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Nital Etched Micrography by OMDf - Ductile Crack