Gray cast iron comprises a-Fe, Fe3C and graphite with their different anisotropies in terms of structure and mechanical behavior. We perform two different deformation paths as tension-compression and compression-tension on bulk gray iron to capture the stress partitioning. Using in situ neutron diffraction, the composite-like deformation behaviors of a-Fe and Fe3C are revealed simultaneously. Within the elastic deformation stage, both deformation paths do not cause load transfer. However, when the applied compressive stress exceeds 300 MPa, there is a clear load sharing in both paths. From microscopic examinations, the debonding between matrix and graphite is clarified.