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ML00046 - Jan.2018

Brittle Fracture of SS Shear Pin

Micrographic detail of the pin structure, in the longitudinal section, at the segregated band with aligned inclusions and phases, delta ferrite and carbides.

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Micrographic detail of the , in the , at the segregated band with aligned inclusions and phases, and carbides.
M

Material

Martensitic Stainless Steel
  • AISI 410
Ds

Description

This is part of a lot that presented pins breaking with large differences in the service loads. The analysis of the pin surface showed that this material did not present a fully by shear, as expected, but regions of a brittle . This unexpected behavior was caused by a combination of a material chemistry with content close to the higher limit and a tempering temperature within the embrittlement range.

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Chemistry (% in weight)

Pin analysis

0.14C; 0.60Si; 0.55Mn; 0.039P; 0.023S; 12.21Cr; 0.33Ni; 0.08Mo; 0.03Nb; 0.12Cu.

Associated Images
Detail of the pin fracture surface, presenting both a flat aspect and a rough aspect in a shearing section of 2.5 mm width.
727
VIEW
ML00046 / Jan.2018
Brittle Fracture of SS Shear Pin
M - Martensitic Stainless SteelP - Machined PartAp - EnergyCd - Intergranular Cracking
Cm - Fractography by SEMDf - Fracture
Fracture appearance in a sheared region, presenting a ductile morphology for the fracture micromechanism.
109
VIEW
ML00046 / Jan.2018
Brittle Fracture of SS Shear Pin
M - Martensitic Stainless SteelP - Machined PartAp - EnergyCd - Intergranular Cracking
Cm - Fractography by SEMDf - Ductile Fracture
Fracture appearance in a brittle region, presenting an intergranular morphology.
93
VIEW
ML00046 / Jan.2018
Brittle Fracture of SS Shear Pin
M - Martensitic Stainless SteelP - Machined PartAp - EnergyCd - Intergranular Cracking
Cm - Fractography by SEMDf - Intergranular Cracking
Micrography of a longitudinal section of the pin, presenting a tempered martensitic structure with aligned delta ferrite and carbide phases.
80
VIEW
ML00046 / Jan.2018
Brittle Fracture of SS Shear Pin
M - Martensitic Stainless SteelP - Machined PartAp - EnergyCd - Intergranular Cracking
Cm - Kalling Etched Micrography by OMDf - Martensite, delta ferrite & carbides
Micrographic detail of the pin structure, in the longitudinal section, at the segregated band with aligned inclusions and phases, delta ferrite and carbides.
70
VIEW
ML00046 / Jan.2018
Brittle Fracture of SS Shear Pin
M - Martensitic Stainless SteelP - Machined PartAp - EnergyCd - Intergranular Cracking
Cm - Kalling Etched Micrography by OMDf - Martensite, delta ferrite & carbides
Micrographic detail of the pin structure, in the longitudinal section, presenting a martensitic matriz, aligned inclusions (grey, delta ferrite islands (poligonal white phases) and carbides (also white phases) surrounding the delta ferrite.
64
VIEW
ML00046 / Jan.2018
Brittle Fracture of SS Shear Pin
M - Martensitic Stainless SteelP - Machined PartAp - EnergyCd - Intergranular Cracking
Cm - Kalling Etched Micrography by OMDf - Martensite, delta ferrite & carbides
Aspect of the broken shear pin that was manufactured in a martensitic stainless steel forged bar, machined with the external diameter of 50mm, the internal diameter of 20mm and the shearing diameter of 25mm (shearing thickness 2.5mm). The fracture, in the right side of the figure, is not fully flat as should be expected for a shearing mechanism.
55
VIEW
ML00046 / Jan.2018
Brittle Fracture of SS Shear Pin
M - Martensitic Stainless SteelP - Machined PartAp - EnergyCd - Intergranular Cracking
Cm - Aspect Before AnalysisDf - General View