Welding electrode and method of forming a resistance spot weld joint

A welding electrode comprising:

• an electrode holder;
• and
• an electrode cap removably attached to said electrode holder and having a central longitudinal axis, said electrode cap including:
• a body having a proximal end and a welding surface spaced apart from said proximal end, wherein said welding surface is substantially smooth and free from any grooves defined therein, and has a first diameter of from about 7 mm to about 10 mm, a first radius of curvature, and a second radius of curvature that is different from said first radius of curvature;
• and
• a skirt portion extending away from said body along said central longitudinal axis and configured to bear against said electrode holder to thereby removably attach said electrode cap to said electrode holder;
• wherein said skirt portion has a first face that is substantially parallel to said central longitudinal axis and spaced apart from said welding surface;
• wherein said body has a second face interconnecting said first face and said welding surface;
• wherein said body tapers from said first face to said welding surface along said second face;
• wherein said second radius of curvature is greater than said first radius of curvature;
• wherein said welding surface includes a protuberance spaced apart from said second face and having said first radius of curvature, and a shoulder adjoining said protuberance.

A welding electrode comprising:

• an electrode holder;
• and
• an electrode cap removably attached to said electrode holder and having a central longitudinal axis, said electrode cap including;
• a body having a proximal end and a welding surface spaced apart from said proximal end, wherein said welding surface is substantially smooth and free from any grooves defined therein, has a first diameter of from about 7 mm to about 10 mm, and includes;
• a protuberance spaced apart from said second face, wherein said protuberance has a first radius of curvature of from about 8 mm to about 40 mm and a second diameter of from about 4 mm to about 7 mm;
• and
• a shoulder adjoining said protuberance;
• wherein said welding surface has a second radius of curvature that is different from said first radius of curvature;
• and
• a skirt portion extending away from said body along said central longitudinal axis and defining a cooling channel, wherein said skirt portion is configured to bear against said electrode holder to thereby removably attach said electrode cap to said electrode holder;
• wherein said skirt portion has a first face that is substantially parallel to said central longitudinal axis and spaced apart from said welding surface;
• wherein said body has a second face interconnecting said first face and said welding surface;
• wherein said body tapers from said first face to said welding surface along said second face so that said shoulder adjoins said second face.