Investigation of the magnetization processes in melt-quenched Nd2Fe14B materials has been made by analysis of measurements of the time dependence of the magnetizing curves (after thermal demagnetization) and demagnetizing curves at room temperature. The quantities S (the magnetic viscosity parameter) and chi(irr)i (the intrinsic irreversible susceptibility) have been determined for the commercially available materials MQI (isotropic, resin bonded), MQII (slightly anisotropic, hot pressed), and MQIII (anisotropic, hot formed) produced by Delco Remy, U.S. In addition deltaM(H), which compares the fraction of irreversible processes occurring at a particular field in the magnetizing mode with those occurring at the same field in the demagnetizing mode, has been determined as a function of internal field, and the results are interpreted in terms of interactions between grains. From these results it is shown that although the magnetization and demagnetization behavior of these materials differ substantially, this may be attributed to differences in the domain structure. There is no evidence that the mechanism for hardening is different from that of the sintered materials.