Definition: A depression left at the termination of the weld where the weld pool is left unfilled. Cause: Improper weld termination techniques Repair: If no cracks exist, simply fill in the crater. Generally welding from beyond the crater back into the crater. Longitudinal Crack Definition: A crack running in the direction of the weld axis. May be found in the weld or base metal. Cause: Preheat or fast cooling problem. Also caused by shrinkage stresses in high constraint areas. Prevention: Weld toward areas of less constraint. Also preheat to even out the cooling rates. Repair: Remove and reweld Transverse Crack Definition: A crack running into or inside a weld, transverse to the weld axis direction. Cause: Weld metal hardness problem Crater Crack Definition: A crack, generally in the shape of an ôXö which is found in a crater. Crater cracks are hot cracks. Cause: The center of the weld pool becomes solid before the outside of the weld pool, pulling the center apart during cooling Prevention: Use crater fill, fill the crater at weld termination and/or preheat to even out the cooling of the puddle Throat Crack Definition: A longitudinal crack located in the weld throat area. Cause: Transverse Stresses, probably from shrinkage. Indicates inadequate filler metal selection or welding procedure. May be due to crater crack propagation. Prevention: Correct initial cause. Increasing preheat may prevent it. be sure not to leave a crater. Use a more ductile filler material. Repair: Remove and reweld using appropriate procedure. Be sure to correct initial problem first. Toe Crack Definition: A crack in the base metal beginning at the toe of the weld Cause: Transverse shrinkage stresses. Indicates a HAZ brittleness problem. Prevention: Increase preheat if possible, or use a more ductile filler material. Root Crack Definition: A crack in the weld at the weld root. Cause: Transverse shrinkage stresses. Same as a throat crack. Prevention: Same as a throat crack Underbead Crack Definition: A crack in the unmelted parent metal of the HAZ. Cause: Hydrogen embrittlement Prevention: Use LOW HYDROGEN electrodes and/or preheat Repair: (only found using NDT). Remove and reweld. Hot Crack Definition: A crack in the weld that occurs during solidification. Cause: Micro stresses from weld metal shrinkage pulling apart weld metal as it cools from liquid to solid temp. Prevention: Preheat or use a low tensile filler material. Repair: Remove and reweld, correct problem first, preheat may be necessary, increase weld size. Cold Crack Definition: A crack that occurs after the metal has completely solidified Cause: Shrinkage, Highly restrained welds, Discontinuities Prevention: Preheat, weld toward areas of less constraint, use a more ductile weld metal Repair: Remove and reweld, correct problem first, preheat may be necessary. Repairs to Cracks Determine the cause Correct the problem Take precautions to prevent reoccurrence Generally required to repair using a smaller electrode Here is a link to a powerpoint presenation. http://pntbeldyk.wirefire.com
An impact crater is an approximately circular depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the.
Metal and Metallurgy engineering FAQ
Why do you get 'crater cracks' in aluminum and how do you prevent them? Crater cracks happen for three reasons: 1. High thermal rate of conductivity.
Weld Crater Cracks
Weld Defects - Cracks. Causes and Types of Cracking that may occur in Welds Cracking in WeldsWe know that several types of imperfections may occur in a weld or the.
Why do you get 'crater cracks' in aluminum and how do you prevent them? Crater cracks happen for three reasons: 1. High thermal rate of conductivity.
9 LONGITUDINAL CRACKING Longitudinal or. is called a crater crack. These are small cracks which appear at the. propagate into the weld bead. A crater crack is.