A quick coupling device for fluid lines comprises a coupling socket for receiving a coupling plug and a locking mechanism. It includes a locking sleeve axially displaceable on the coupling socket and at least one radially movable locking ball arranged in a bore of the coupling socket. The at least one locking ball is radially movable and lockable by the locking sleeve. The device includes a temperature-controlled locking element which is arranged on the coupling socket or on the locking sleeve and engages an undercut arranged in the locking sleeve or the coupling socket when a temperature threshold is exceeded.