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ML00153 - Jan.2019

X52 in a Tubular Structure

Micrographic detail of the bainitic structure of the coarse grain heat affected zone, close to the fusion line (to the top of the figure).

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Micrographic detail of the bainitic of the coarse grain , close to the (to the top of the figure).
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Material

CMn Steel
  • API 5L grade X52
Ds

Description

The procedure of the 5LX52 was qualified according to the structural code, with tougness requirements. The grain refined was welded using matching and the is ferritic, acicular in the fill and and equiaxial in the reheated root. Interesting to observe that the rupture of one testpiece was in the base metal and the other in the weld metal, all presenting a tensile strength level higher than the minimum specified.

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Chemistry (% in weight)

Pipe Analysis

0.128C; 0.23Si; 1.30Mn; 0.025P; 0.011S; 0.04Cr; 0.01Ni; 0.06Mo; 0.038V.

Associated Images
Macrography of a section longitudinal to the pipe and transverse to the weld. The thickness of the pipe is 12,7 mm (1/2") and it was welded in 6 passes, the root pass, one fill pass and four cap passes.
855
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - NItal Etched MacroDf - Welded Joint
Micrography of the pipe base metal, in a longitudinal section, presenting a slight banding and a refined structure.
147
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrography of the pipe base metal, in a longitudinal section. The ferritic structure is refined and it is possible to identify a small variation in the ferritic grain size, that is promoting the slight banding effect.
119
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Base Metal
Micrographic detail of the very refined ferritic structure of the base metal, in the longitudinal section, indicating that the material was heat treated, since no banding is not detectable at this magnification.
101
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Grain refined structure
Schematic drawing of the API 5L X52 pipe, butt welded to another pipe, showing the 4 cap passes. The pipe is nominal diameter 8" and thickness 1/2". The qualification of the WPS was conducted according to the structural code, with toughness requirements (Charpy V at 0°C), with 4 lateral bending tests, all approved, and 2 welded joint tensile tests, one with ruptured in the base metal and the other ruptured in the weld metal, both presenting strenght level higher than the minimum specified. The pipe was tensile tested.
95
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Identification drawingDf - Welded Joint
Micrography of the weded joint at the cap pass fusion line. The columnar structure of the weld metal is to the top of the figure; and it is possible to see the coarse grains at the heat affected zone. Both columnar structure and coarse grains are related to the previous austenite grain boundaries. From the fusion line to the base metal (in the bottom of the figure) the grain sizes are refined.
86
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Welded Joint
Micrography presenting the coarse grain heat affected zone of the welded joint, at the cap pass. The microstructure is bainitic.
82
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Heat Affected Zone
Micrographic detail of the bainitic structure of the coarse grain heat affected zone, close to the fusion line (to the top of the figure).
76
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Bainitic HAZ
Micrography of the weld metal in the region of the cap pass that was not reheated, last bead, presenting previous austenite columnar grains, coarse.
69
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Welded Joint
Micrography of the weld metal in the last bead, presenting previous austenite columnar grains, primary ferrite in the grain boundaries, some regions of ferrite with aligned second phases and acicular ferrite.
58
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by SEMDf - Weld Metal
Micrographic detail of the weld metal in the last bead. The microstructure shows primary ferrite in the (previous austenite) grain boundaries, some regions of ferrite with aligned second phases and acicular ferrite in the center of the columnar grains.
51
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Columnar Grains
Micrography of the weld metal in the root, reheated by the fill pass, presenting a refined ferritic structure.
49
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Welded Joint
Micrography of the weld metal in the root, reheated by the fill pass, presenting a refined ferritic structure and some islands of second phases, probably agglomerated carbides.
46
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Weld Metal
Micrographic detail of the refined ferritic microstructure, with equiaxial grains, of the weld metal in the root, reheated by the fill pass. At this magnification it is possible to see that the agglomerated carbides ar located in ferritic grain boundaries.
67
VIEW
ML00153 / Jan.2019
X52 in a Tubular Structure
M - CMn SteelP - Seamless PipeAp - StructureCd - Qualified
Cm - Nital Etched Micrography by OMDf - Equiaxial Grains