A grinding or grating noise that shows up mostly when you turn is a specific clue. It can be a brake problem, but it can also be something nearby. Here is what causes brake grinding when turning.
Worn-out pads
The most common brake cause is pads worn down to the metal backing plate, so the steel grinds the rotor - and turning changes the load on the pad, making the noise come and go; see why brakes grind. This needs immediate attention before it destroys the rotor; see wear patterns.
A stuck caliper or debris
A sticking caliper drags a pad unevenly, and cornering forces can make it grind or scrape; see sticking caliper. A stone or bit of debris caught between the rotor and dust shield also grinds, often changing with turns as parts flex.
When it is NOT the brakes
Grinding or growling that changes clearly with steering - louder turning one way, quieter the other - is often a failing wheel bearing, not the brakes. Bearings are loaded differently in turns. If the noise is speed-related and directional, have the bearing checked too.
What to do
Do not ignore grinding - inspect the pads first, then the caliper and dust shield, then the wheel bearing. Replace worn pads promptly and service the hardware; see caliper slide pins. Fit quality pads and hardware.