Method of welding wallpaper alloy an arc welder modified to practice same

In a short circuit arc welding apparatus comprising a D.C. power supply means for causing a welding current of different levels to pass through a welding wire and a workpiece at a molten metal pool on said workpiece, wire feeding means for feeding said wire from said holder toward said workpiece whereby said welding wire is subjected to a succession of welding cycles, each of said welding cycles including an arcing condition during which said wire is spaced from said pool and the energy applied to said wire exceeds a given value raising the temperature at the end of said wire to a molten temperature to form a molten metal ball on the end of said wire and a short circuit condition during which said molten metal ball on the end of said wire first contacts said molten metal pool and then transfers from said wire to said workpiece by a necking action breaking said molten metal ball from said wire to initiate an arc in a subsequent welding cycle, and means for creating plasma boost portion with a set peak current level, means for creating a plasma portion following said plasma boost portion and having a decreasing current level, and means for creating a set background current level, said plasma boost portion, plasma portion and a portion of said background current constituting said arcing condition, the improvement comprising:

• a capacitor, means for charging said capacitor to a voltage level representative of said peak current level, a resistor with a resistance value to discharge said capacitor in an RC time constant relationship toward a voltage level representative of said background current, means for controlling the curve of said decreasing current during said plasma portion from said peak current level to said background current level by the voltage on said capacitor and an exposed means on said welder for manually adjusting said resistance value of said resistor to adjust the heat created during said plasma portion.

A method of welding a corrosion resistant, wallpaper alloy to the inside surface of a vessel wall formed from a corrosion susceptible steel sheet after said wallpaper alloy has been affixed to said inside to provide an exposed seam of said wallpaper alloy extending in a given path, said method comprising the steps of:

• (a) moving a welding wire toward said seam and along said path;
• (b) melting and depositing said welding wire onto said seam along said path by a short circuit arc welding process of the type having a welding cycle with a short condition and an arcing condition, which arcing condition constitutes a plasma boost portion with a peak current level followed by a plasma portion with a current decreasing from said peak current level toward a set background current level with a given time between said plasma boost portion and said short condition of said welding cycle;
• and,
• (c) setting the length of time of said plasma portion of said arcing condition to a value greater than 2.0 ms.

A method of welding a corrosion resistant, wallpaper alloy to the inside surface of a vessel wall formed from a corrosion susceptible steel sheet after said wallpaper alloy has been affixed to said inside to provide an exposed seam of said wallpaper alloy extending in a given path, said method comprising the steps of:

• (a) moving a welding wire toward said seam and along said path;
• (b) melting and depositing said welding wire onto said seam along said path by a short circuit arc welding process of the type having a welding cycle with a short condition and an arcing condition, which arcing condition constitutes a plasma boost portion with a set peak current level followed by a plasma portion with a current decreasing from said peak current level toward a set background current level with a given time between said plasma boost portion and said short condition of said welding cycle;
• and,
• (c) increasing the heat energy of said cycle by increasing the length of time of said plasma portion of said arcing condition for a given background current level.

A method of welding a high nickel corrosion resistant, wallpaper alloy to the inside surface of a vessel wall formed from a corrosion susceptible steel sheet after said high nickel wallpaper alloy has been affixed to said inside to provide an exposed seam of said wallpaper alloy extending in a given path, said method comprising the steps of:

• (a) moving a welding wire toward said seam and along said path;
• (b) melting and depositing said welding wire onto said seam along said path by a short circuit arc welding process of the type having a welding cycle with a short condition and an arcing condition, which arcing condition constitutes a plasma boost portion with a set peak current level followed by a plasma portion with a current decreasing from said peak current level toward a set background current level with a given time between said plasma boost portion and said short condition of said welding cycle;
• and,
• (c) causing said decreasing current to decrease from said plasma boost in a RC time constant curve.