JCT400

When welding carbon steel to any member that is coated with galvanize, it is imperative that all galvanize coating from the proposed weld area be remove, down to bare metal. Your weld with the coating intact became loaded with porosity along with no penetration, in addition it was thus very brittle.
Grinding out all the laid on weld material back to parent metal and a correct weld applied and as the term "good to go"
applies.

Factors to insure a quality weld..length of arc, speed of travel, correct current amperage,and of course proper filler metal.

Good Luck