The damage of copper backing shoes during root pass in GMAW

The damage of copper backing shoes during root pass in GMAWCLANDIA SIM

Internal Line-Up Clamp (ILUC)Root passAvoid misalignmentCopper or ceramic shoes

Copper backing shoesDamage after a degree of usage (number of welds)Replace according to DNV-OS-F101Not a clear statement

Copper InclusionCommon defect listed in DNV-OS-F101Probably associated with Copper Contamination Cracking (CCC)Research on CCC in late 1970s early 1980s 4 conditions that made CCCLiquid and solid metal

Tensile stress Plastic deformationNo intermetallic compoundHigh/Low solubility gradientHigh/Low melting point gradient

Method: Materials Preparation1m19cm

Method: GMAW Welding

Shielding gas: Mixture of 86% Argon, 12% CO2 and 2% OxygenElectrode: AWS A5.18 E70S-6 copper coated steel wire4 welds

Method: Material examinations

Visual inspection CameraOxide formation

Microscope LEICA MZ6Number of pitsSurface area of damage

8

Key Result 1: Oxide formation

Less as increase number of weldsWELD1WELD2WELD3WELD4WELD1WELD2WELD3WELD4

WELD1WELD2WELD3WELD4WELD1WELD2WELD3WELD4WELD1WELD2WELD3WELD4

Key Result 2: No. of pits and damage area vs No. of welds

Key Result 3: No. of pits and damage area vs different level of gaps

Key Result 4: Molten bits formation

Started to form after 4th weldMuch smaller, within the previous mentioned oxide pits

SummaryRepeating weldsNo. pits increase, area of damage increase

Less oxide layer formed

Molten bits started to form after 4th welds

Easier to get copper inclusion

Future WorksContinueUnit pX to mmInput Weld 4 result more effectively ImprovementMass of OxideDepth of the damageResearch questionsCopper inclusion>>CCCSolution for CCC solve for copper inclusionTo DoNumber of weldsFull scale model NDT on steel plate

Thank you for listeningAny questions?