why welds crack poster - lincoln electric · 2015. 9. 1. · why welds crack wc-515 08/15 ©lincoln...
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WC-515 08/15 ©Lincoln Global, Inc. All Rights Reserved.
Heat Affected Zone Crack(Underbead Crack)
Crater Crack Transverse Crack
Longitudinal Crack(Centerline Crack)
» Joint Restraint » Improper Bead Shape
» High Carbon/Alloy Content » Low Melting Point Contaminants
» Hydrogen Pickup » Rapid Cooling Rate
Possible Causes Excess HydrogenHigh Carbon/Alloy Content in Base MetalHigh Residual Stress Levels
Possible Cures Use Low Hydrogen ConsumablesControl Hydrogen Content in Weld MetalIncrease Pre-HeatIncrease Post-Heat
Possible Causes Inadequate Crater Fill
Possible Cures Backstep at the End of the WeldUser Crater Fill Machine Settings
Possible Causes Excess HydrogenExcess Strength in Weld MetalHigh Residual Stress Levels
Possible Cures Increase Pre-HeatUse Lower Strength Consumables (consistent with design requirements)Increase Post-Heat
Possible Causes Improper Width to Depth RatioLow Melting Point ContaminantsConcave Weld Surface
Possible Cures Use Width to Depth Ratio of 1:1 to 1.4:1Limit Excess PenetrationDecrease Voltage and/or Travel Speed
DURING FABRICATION
Why Welds Crack
WC-515 08/15 ©Lincoln Global, Inc. All Rights Reserved.