N1 Welding Shielded Metal Arc Welding

Good day everyone I AM MRS MAPHALLA(MAKUBO) WELDING LECTURER SHIELDED METAL ARC WELDING ( DEFECTS,CAUSES AND REMEDIES ) Downloaded from hlayiso.com

Spatter occurs when small particles from the weld attach themselves to the surrounding surface .its an especially common occurrence in a gas metal arc welding Downloaded from hlayiso.com

Causes  The running amperage is too high  Voltage setting is too low  Incorrect polarity  The work angle of the electrodes is too steep Downloaded from hlayiso.com

Remedies  Reduce the arc length  Adjust the weld current  Increase the electrode angle  Use proper polarity Downloaded from hlayiso.com

Incomplete penetration occurs when the groove of the metal not filled completely, meaning the weld metal doesn’t fully extend through the joint thickness Downloaded from hlayiso.com

Causes  There was too much space between the metal you’re welding together  You’re moving the bead too quickly, which doesn’t allow enough metal to be deposited in the joint  Large electrodes diameter  Misalignment  Improper joint Downloaded from hlayiso.com

Remedies  Use proper joint geometry  Use a properly sized electrode  Reduce arc travel speed  Choose proper welding current Downloaded from hlayiso.com

Weld crack The most serious type of welding defects is a weld crack and it’s not accepted almost by all .it can appear on the surface, in the weld metal or the area affected by the intense heat Downloaded from hlayiso.com

Causes  Use of hydrogen when welding ferrous metal  Residual stress caused by the solidification shrinkage  Base metal contamination  No preheat before starting welding Remedies  Preheat the metal as required  Provides proper cooling of the weld area  Use proper joint  Remove impurities  Downloaded from hlayiso.com

The focus was on welding defects, causes and remedies  The next presentation will focus on shielded metal arc welding practical's. Downloaded from hlayiso.com