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ML00004 - Jun.2018

Creep in High Temperature Bolts

Micrographic detail of the creep voids and interconnected cracks. The broken bolt remained in service during some time and the fracture surface presented a thick oxide layer(grey). As polished.

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Micrographic detail of the and interconnected . The broken remained in service during some time and the surface presented a thick (grey). .
M

Material

CrMo Steel
  • ASTM A 193 grade B16
Ds

Description

The has failed in service in a turbine that was operating in temperatures a little higher than the designed. The surface presented a thick oxide and the internal is overtempered and presenting .

C

Chemistry (% in weight)

Product Analysis

0.42C; 0.29Si; 0.57Mn; 0.014P; 0.018S; 0.91Cr; 0.63Mo; 0.26V.

Associated Images
Micrography of a longitudinal section of the bolt at the fracture surface. The material showed several creep voids and interconnected cracks. The broken bolt remained in service during some time and the fracture surface presented a thick oxide layer(grey). As polished.
529
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Micrography by OMDf - Oxide Layer
Micrographic detail of the creep voids and interconnected cracks. The broken bolt remained in service during some time and the fracture surface presented a thick oxide layer(grey). As polished.
121
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Micrography by OMDf - Interconnected Cracks
Micrographic detail of the creep voids and interconnected cracks. The broken bolt remained in service during some time and the fracture surface presented a thick oxide layer(grey). As polished.
101
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Micrography by OMDf - Voids
Micrography of a longitudinal section of a CrMov steel bolt that broke in service by a creep mechanism in a gas turbine. Tempered structure. Interconnected cracks paralled to the fracture surface.
95
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Nital Etched Micrography by OMDf - Crack
Micrographic detail of a longitudinal section of the bolt far from the fracture, presenting a tempered structure.
82
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Nital Etched Micrography by OMDf - Tempered Structure
Micrographic detail of a longitudinal section of the bolt close to the fracture, presenting an overtempered structure.
76
VIEW
ML00004 / Jun.2018
Creep in High Temperature Bolts
M - CrMo SteelP - FastenerAp - Gas TurbineCd - Creep
Cm - Nital Etched Micrography by OMDf - Overtempered Structure