The load transfer among ferrite orientations and between ferrite and martensite was analysed in DP 600 steel by means of neutron diffraction during in situ tensile tests on the multiple pulse overlap time-of-flight strain scanner POLDI. The material had 0.07 wt% C and a martensite volume fraction of 15%. In situ tests were done in “Young” as well as in “Poisson setup”. The martensite phase could not be probed due to its low tetragonality. The curves of the lattice plane strains as a function of the externally applied macroscopic stress reveal (1) plastic relaxations of transformation and intergranular stresses in the compliant <100> oriented grains, and (2) a second inflection point in the fully plastic part indicating the onset of plastic deformation of the hard phase.