Heya, While I was changing brake rotors I noticed some odd and rather concerning lines in my rotors(present on both front rotors), I suspect they are welds but would like to know for sure for peace of mind. 2002 Mazda 6 gsx. Cheers,
Hard to tell via pictures w/o close examination but it appears to be the start of stress fatigue. A machine shop might be able to tell you the extent. It could also be gouging from poor quality pads previously and new materials having been compressed into the gouge..
OEM rotor blanks are cheap and easy enough to replace. I'd do that.