Similar to Fig. 7 but for a model with M_ZAMS = 47.5 M_⊙ at Z = 0.4 Z_⊙ metallicity. The two upper panels a and b are centered on the evolutionary phase during which the radius substantially increases, which is mainly the phase of rapid HG expansion. The different structural response of the envelope to the outer convective zone in panel c, associated with differences in the abundance profile in panel d, leads to a much smaller impact of the increasing f_conv on the envelope binding energy E_bind (see text for details).