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ML00059 - Feb.2018donated by: David Hadjadj

Intergranular Corrosion of Aluminum Piping

Intergranular corrosion at the fusion line of the AA 6063 pipe.

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at the of the 6063 .
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Material

Aluminum Manganese
  • NF EN 755-7 EN AW 3003
  • NF EN 755-7 EN AW 6063
Ds

Description

A has occurred in a Nitric Acid pipeline, at the between 6063 (probably temper T6) and AA 3003 (probably temper O), due to associated to strong precipitation at the AA 6063 . The successfully adopted alloy for this Concentrated Nitric Acid is the alloy AA 3003 temper O (controlled and contents). The AA 6063, a moderately high strength alloy ( by Mg2Si phase), is not typically applied for nitric acid.

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Chemistry (% in weight)

3003 Pipe

0.17Si; 0.32Fe; 0.12Cu; 1.28Mn; 0.02Mg; 0.02Cr; 0.02Zn; 0.03Ti.

6063 Pipe

0.58Si; 0.22Fe; 0.02Cu; 0.07Mn; 0.63Mg; 0.04Cr; 0.01Zn; 0.02Ti.

Weld Metal

0.19Si; 0.18Fe; 0.02Cu; 0.21Mn; 0.11Mg; 0.004Cr; 0.007Zn; 0.02Ti.

Associated Images
Internal surface detail of the 3 1/2" pipe, cut in a longitudinal section (transverse to the weld), presenting a localized corrosion at the margin of the welded joint (Keller etched), in the root. The pipeline was assembled with pipes manufactured in two different aluminum alloys, AA 3003 (top of the figure) and AA 6063 (bottom of the figure), and the localized corrosion occurred at the fusion line of the 6063 pipe.
1296
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Surface AspectDf - Welded Joint
The macrography of the welded joint shows the AA 6063 alloy pipe in the right and the AA 3003 pipe in the left, welded in two passes. The root presents small regions of corrosion in the weld metal and a localized corrosion at the fusion line of the 6063 pipe (knife-line attack morphology).
397
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched MacroDf - Localized Corrosion
Micrography of a longitudinal section of the pipe AA 3003. Granular structure that reveals the forming direction and dispersed particles.
229
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Base Metal Left Side
Micrographic detail of a longitudinal section of the pipe AA 3003. Granular structure and dispersed particles.
199
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Base Metal Left Side
Micrography of a longitudinal section of the pipe AA 6063. Granular structure and dispersed particles.
169
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Base Metal Right Side
Micrographic detail of a longitudinal section of the pipe AA 6063. Granular structure and dispersed particles.
138
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched MacroDf - Base Metal Right Side
Micrography of the Fusion Line of the AA 3003 pipe, presenting a narrow HAZ.
127
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Fusion Line Left Side
Micrography of the Fusion Line of the AA 3003 pipe, presenting a narrow HAZ.
110
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Fusion Line Left Side
Micrographic detail of the Fusion Line of the AA 3003 pipe, presenting a narrow HAZ.
93
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Fusion Line Left Side
Micrography of the Fusion Line of the AA 6063 pipe, presenting strong precipitation.
94
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Fusion Line Right Side
Micrography of the Fusion Line of the AA 6063 pipe, presenting strong precipitation.
88
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Fusion Line Right Side
Micrographic detail of of the Fusion Line of the AA 6063 pipe, presenting strong precipitation.
88
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Fusion Line Right Side
Intergranular corrosion at the fusion line of the AA 6063 pipe.
81
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Localized Corrosion
Intergranular corrosion at the fusion line of the AA 6063 pipe, that presents strong precipitation.
89
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Localized Corrosion
Micrographic detail of the intergranular corrosion at the fusion line of the AA 6063 pipe.
72
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Localized Corrosion
Micrography of the weld metal structure. At the interface between the two passes, close to the AA 3003 pipe.
50
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Weld Metal
Weld metal structure.
44
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Weld Metal
Micrographic detail of the weld metal structure.
53
VIEW
ML00059 / Feb.2018
Intergranular Corrosion of Aluminum Piping
M - Aluminum ManganeseP - Welded JointAp - Chemical IndustryCd - Intergranular Corrosion
Cm - Keller Etched Micrography by OMDf - Weld Metal