Back to Low Alloy Medium Carbon QT
ML00082 - Dec.2017

Corrosion Fatigue of a Drilling Tool

Micrographic aspect of the martensitic structure at the longitudinal section.

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Micrographic aspect of the martensitic at the .
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Material

Low Alloy Medium Carbon QT
  • AISI 4330V
Ds

Description

The drilling tool was broken, at the end position, during operation in conditions of severe torque variation. The flat presented characteristics initiated from the outside, where there was a geometrical change. Multiple were evident and the fracture was partially eroded by .

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Chemistry (% in weight)

Product Analysis

0.33C; 0.21Si; 0.84Mn; 0.021P; 0.008S; 0.85Cr; 1.90Ni; 0.38Mo; 0.02Cu; 0.074V.

Associated Images
Micrography of the external surface of the tubular equipment, close to the fracture position (it is to the top of the figure), showing multiple cracks, typical of a corrosion fatigue mechanism.
861
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Multiple cracks
Drilling tool that broke close to the region of the male connector (pin end). The fracture is at the right side of the figure.
102
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Fracture
The fracture was removed from the failed part and analyzed separately. The aspect of the fracture surface is presented. It is flat, with regions of fatigue propagation and with regions of erosion by washout (to the right side of the figure).
80
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Fracture
Detail of the fracture surface presenting a fatigue propagation from the outside of the tool.
69
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Fatigue Fracture
Detail of the fracture surface presenting erosion by a washout, because the equipment was pressurized when the cracking became through wall.
63
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Washout
Micrographic aspect of the martensitic structure at the longitudinal section.
60
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Martensite
Micrography of the quenched and tempered structure. Longitudinal section.
51
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Banded Structure
Micrography of the quenched and tempered structure. Longitudinal section. Sligthly banded.
45
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Banded Structure
As polished micrography of the external surface of the tubular equipment, close to the fracture position (it is to the top of the figure), showing corrosion fatigue cracks. These are multiple cracks, paralel to the main fracture, slightly branched and fully filled with oxides.
51
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - As polished micrographyDf - Multiple cracks
As polished micrography of the external surface of the tubular equipment, close to the fracture position (it is to the top of the figure), showing corrosion fatigue cracks. These are multiple cracks, paralel to the main fracture, slightly branched and fully filled with oxides.
43
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - As polished micrographyDf - Multiple cracks
Micrography of the external surface of the tubular equipment, close to the fracture position (it is to the top of the figure), showing multiple cracks, typical of a corrosion fatigue mechanism.
47
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Multiple cracks
Micrography of a longitudinal section of the tubular tool, at the external surface close to the fracture position (it is to the top of the figure), showing multiple cracks, slightly branched, fully filled with corrosion products, typical of a corrosion fatigue mechanism. It propagates in a straight front, not affected by banded structures,
53
VIEW
ML00082 / Dec.2017
Corrosion Fatigue of a Drilling Tool
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Fatigue Crack