Guys am a specialist welder by trade and weld alot of diffrent materials every day...alu, alu cast, tool steels, stainless ,nickels, duplexs the lot......i weld alloy wheels every other day sometimes four a day...for 3 different wheel refurb compaines round newcastle.. the weld is stronger than the wheel if you use the correct filler wire and cut the crack out! never have any come backs have been doing this for 5 years now! i have come across ones that have been welded else where and its cracked straight through middle of weld...reasons could be an number of reasons no pre heat, low amprage, silicon based filler, poor gas flow, not cleaned properly, didnt get all of crack or just a poor welder!
i fix cracks,missing bits and flat spots!