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ML00060 - Apr.2017

Brittle Fracture of a Chilled Cast Iron Camshaft

In the center of the shaft thickness the structure is perlitic with graphite in flakes, but there are also islands of ledeburite.

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In the center of the thickness the is perlitic with graphite in flakes, but there are also islands of ledeburite.
M

Material

Chilled Cast Iron
  • ALLOY Non Specified
Ds

Description

The camshaft broke in a brittle way after a short time in operation. The chilled (ledeburitic) extended to the center of the thickness in some lobes. In a region of a raiser (geometric) the presence of a large amount of lebeburite created a condition for .

C

Chemistry (% in weight)

Shaft Analysis

3.85C; 1.64Si; 0.65Mn; 0.016P; 0.022S; 0.11Cr; 0.07Ni; 0.07Mo; 0.05Cu; 0.003V.

Associated Images
The camshaft broke in a brittle way in a region where the shaft changed the geometry, close to a chilled lobe.
551
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - Fracture
The macrography of a longitudinal section of the camshaft (tubular) in a position where there are two chilled lobes, presenting a strong microstructural change through thickness, from the hard chilled surface (500HV10) to the soft region in the middle of the thickness (187HV10).
96
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - NItal Etched MacroDf - Longitudinal Section
Close to the camshaft lobe surface, the chilled casting presents a white cast iron structure. Primary carbides and ledeburite with a hardness level about 50 HRc.
102
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
Micrographic detail of the chilled structure. Primary carbides, ledeburite and perlite islands.
79
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Close to the External Surface
In the center of the shaft thickness the structure is perlitic with graphite in flakes, but there are also islands of ledeburite.
62
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - In the Center of the Thickness
Micrographic detail of the structure in the center of the shaft thickness. Perlitic matrix with graphite in flakes, and ledeburite islands.
53
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - In the Center of the Thickness
In the intermediary position of the shaft thickness (T/4) the amount of perlite increases in the matrix and primary carbides decreases compared to the chilled surface.
54
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - T/4 of the external surface
Micrographic detail of the intermediary position of the shaft thickness (T/4). The amount of perlite increases in the matrix and primary carbides decreases compared with the chilled surface.
55
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - T/4 of the external surface
Micrography transverse to the fracture, showing that the region that broke presented in the shaft thickness a large amount of brittle structures (ledeburite), that suggest a too large extension of the chill effect.
53
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Fracture
Micrographic detail of the structure in a section transverse to the fracture, showing that the brittle region in the shaft is associated to a large amount of ledeburite.
43
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Nital Etched Micrography by OMDf - Fracture
Camshaft in the broken region, close to a lobe where the cast iron was chilled.
48
VIEW
ML00060 / Apr.2017
Brittle Fracture of a Chilled Cast Iron Camshaft
M - Chilled Cast IronP - ShaftAp - AutomotiveCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - Fracture