Arc welding method and arc welding apparatus for adjusting a welding current waveform responsive to a setting voltage adjustment

An arc welding method comprising:

• setting a set current;
• automatically setting an optimal voltage and a first current waveform having a portion that increases with a first constant slope of a short circuit current according to the set current;
• setting a set voltage, and when the set voltage is different from the optimal voltage;
• automatically changing the first current waveform having the portion that increases with the first constant slope of the short circuit current to a second current waveform having a portion that increases with a second constant slope of the short circuit current based on a difference between the optimal voltage and the set voltage;
• and
• starting welding with a consumable electrode by the set current, the set voltage and the second current waveform,
• wherein the setting step of the set current and the changing step of the first current waveform to the second current waveform are performed prior to the step of starting welding, and wherein
• when the set voltage is less than the optimal voltage, the second constant slope is steeper than the first constant slope, and
• when the set voltage is greater than the optimal voltage, the second constant slope is gentler than the first constant slope.