The effect of a strong magnetic field on the synthesis of chemical elements is considered at conditions of nuclear statistical equilibrium. The possibility to employ the produced radionuclides to probe the transient ultra-magnetized astrophysical plasma in supernovae and near neutron stars is analyzed. For iron group nuclides the magnetic modification of the nuclear structure shifts a maximum of nucleosynthesis products towards smaller mass numbers approaching titanium. Signals of 44Ti radioactive decay in the gamma-spectra of the supernova remnant Cassiopeia A are revealed from the Integral IBIS/ISGRI observational data. The determined gamma-ray fluxes for 44Sc* lines with energies 67.9keV and 78.4keV correspond to the initial 44Ti volume (3.3 −0.7 +0.9 ) × 10−4 solar masses that corroborates the magnetic enhancement of isotope production at a field constrained on conditions of supernova explosion.