"During an early attack on Baghdad, one M1A1 was disabled by a recoiless rifle round that had penetrated the rear engine housing, and punctured a hole in the right rear fuel cell, causing fuel to leak onto the hot turbine engine. After repeated attempts to extinguish the fire, the decision was made to destroy or remove any sensitive equipment. Oil and .50 caliber rounds were scattered in the interior, the ammunition doors were opened and several thermite grenades ignited inside. Another M1 then fired a HEAT round in order to ensure the destruction of the disabled tank. Unfortunately, the tank was completely disabled but still intact. Later, an AGM-65 Maverick was fired into the tank to finish its destruction. Ironically the tank still appeared to be intact from the exterior."
"Some were disabled by Iraqi infantrymen in ambushes employing short-range antitank rockets, such as the Russian RPG-7, during the 2003 invasion. This damage usually corresponds to the tracks of the Abrams. Another one was put out of action when heavy machine gun rounds struck fuel stowed in an external rack, starting a fire that spread to the engine."
Those are the whole quotes. As you can see its armour isnt that strong as it was pierced in the rear by an anti tank rifle.