Back to Low Alloy Medium Carbon QT
ML00110 - Jan.2018

Non Conformance in Spray and Fuse Pin

Micrography, as polished, of the transverse section of the forged pin, showing a crack in the thermal spray layer, thickness about 0.8mm. The spray and fuse process was conducted in a low alloy steel, type AISI 4130, but the quenching and tempering heat treatment was not applied later, and the pin body presented low strenght, evidencing plastic deformation after hydrostatic testing, that cause the layer cracking.

10

22
, , of the of the forged , showing a in the layer, thickness about 0.8mm. The spray and fuse process was conducted in a , type , but the quenching and tempering was not applied later, and the body presented low strenght, evidencing after hydrostatic testing, that cause the layer .
M

Material

Low Alloy Medium Carbon QT
  • AISI 4130
  • UNS G41300
  • Commercial Name Colmonoy 5
Ds

Description

A and fuse layer was applied to the sealing surface of the to assure resistance as well as resistance, but the pin body was not heat treated after the fuse of the layer, and during hydrostactic tests to qualify the pin it was fully cracked. The low strenght, low toughness, - was not able to support the pressure. The body should be after the process.

C

Chemistry (% in weight)

Pin analysis

0.28C; 0.22Si; 0.55Mn; 0.007P; 0.008S; 0.92Cr; 0.04Ni; 0.21Mo; 0.02Cu.

Associated Images
Longitudinal cracks in the surface of the pin, detected by dye check, after high pressure hydrostatic test.
658
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - Aspect by NDTDf - General View
Micrography, as polished, of the transverse section of the forged pin with the layer applied by a (thermal) spray and fuse process. The layer presented entrapped pores and globular oxides. It was melted after application by thermal spray (in this case using a flame) but the pin was not heat treated after the full application and melting of the layer and the base metal is ferritc-pearlitic.
51
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Transverse Section
Micrography, as polished, of the transverse section of the forged pin with the layer applied by a (thermal) spray and fuse process. The layer was melted after thermal spray application and the layer presents a continuous matrix, but there are globular oxides and pores entrapped.
36
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Surface Layer
Micrographic detail, as polished, of the transverse section of the forged pin at the interface between the pin and the spray and fuse layer. The interface presents globular oxides and small pores, entrapped.
35
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Surface Layer
Low magnification micrography of the interface between the pin and the spray and fuse layer. Close to the surface, under the layer, the pin presents a ferritic perlitic structure, non conform with the high strenght requirement. Transverse section.
37
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Low Mag
Micrography of the pin close to the interface with the spray and fuse layer. Transverse section. The fuse was conducted in high temperature and the pin was cooled very slowly, forming a ferritic-perlitic structure even for this high hardenability base metal.
35
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Low magnification micrography of the pin in the center of the 25 mm thickness. Ferritic-pearlitic structure of the material that slowly cooled after spray and fuse application. Transverse section.
25
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrography of the ferritic-pearlitic structure in the center of the thickness of the tubular forging pin. Transverse section. The fuse is conducted in high temperature and the pin was not heat treated after the thermal spray deposition and fuse.
23
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrographic detail of the ferritic-pearlitic structure in the center of the thickness of the tubular forging pin. Transverse section. The fuse is conducted in high temperature and the pin was not heat treated after the thermal spray deposition and fuse.
21
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - Nital Etched Micrography by OMDf - Ferrite and Pearlite
Micrography, as polished, of the transverse section of the forged pin, showing a crack in the thermal spray layer, thickness about 0.8mm. The spray and fuse process was conducted in a low alloy steel, type AISI 4130, but the quenching and tempering heat treatment was not applied later, and the pin body presented low strenght, evidencing plastic deformation after hydrostatic testing, that cause the layer cracking.
22
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Cracks Transverse to the Surface
Micrographic detail of the crack in the thermal spray layer. The spray and fuse layer presented a typically melted structure with entrapped pores and globular oxides.
29
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Crack
Micrographic detail, as polished, of the transverse section at the interface between the pin and the spray and fuse layer. The interface presents globular oxides and small pores, entrapped.
23
VIEW
ML00110 / Jan.2018
Non Conformance in Spray and Fuse Pin
M - Low Alloy Medium Carbon QTP - Tubular ForgingAp - O&G Well DrillingCd - Heat Treatment Defect
Cm - As polished micrographyDf - Surface Layer