By using isochronous mass spectrometry at the experimental cooler storage ring in Lanzhou, China, masses of short-lived Cr44, Mn46, Fe48, Co50, and Ni52 were measured for the first time and the precision of the mass of Ti40 was improved by a factor of about 2. Relative precisions of δm/m=(1-2)×10-6 have been achieved. Details of the measurements and data analysis are given. The obtained masses are compared with the Atomic-Mass Evaluation 2016 and with theoretical model predictions. The new mass data enable us to extract the higher-order coefficients, d and e, of the quartic form of the isobaric multiplet mass equation for the fp-shell isospin quintets. Unexpectedly large d and e values for the A=44 quintet are found. By revisiting the previous experimental data on β-delayed protons from Cr44 decay, it is suggested that the observed anomaly could be due to the misidentification of the T=2, Jπ=0+ isobaric analog state in V44.