An innovative experimental set-up for fast X-ray diffraction analysis on polycrystalline materials has been established at the synchrotron radiation facility ANKA (Karlsruhe, Germany). Key components of the set-up are two fast microstrip line detectors arranged symmetrically around the incident beam in the backscatter region. The capabilities of the set-up are tested by means of in-situ heat treatment experiments on SAE 4140 steel samples. In this feasibility study the heat was introduced by means of either a heating stage or by means of a gas tungsten arc welding torch. It will be shown that the evolution of thermal and elastic lattice strains can be monitored at a sampling rate of up to 4 Hz at a bending-magnet synchrotron beamline. Since the sampling rate may be increased further at a insertion device synchrotron beamline providing higher photon flux, our setup appears to be feasible for monitoring laser treatments in real time.