Table 1.
Chemical composition of rolled steel (mass fraction, %).
Figure 1.
Illustration of preset internal crack in workpiece before rolling.
Table 2.
Experimental parameters.
Figure 2.
SEM image of crack healing under different reduction rates (a) 20%, (b) 40%, (c) 50%, and (d) 60%.
Figure 3.
Tensile strength of matrix specimens and specimen with preset crack.
Figure 4.
Crack healing process sequence, (a) recrystallization at the free crack surfaces, (b) shrinking the gap, (c) crack surfaces partially joined, (d) intermittent partial crack healing, (e) grains at the interface grow to matrix grains.
Figure 5.
Distribution of porosity defects at crack healing zone.
Figure 6.
Recrystallization at the crack healing zone.
(a) continuous recrystallization and merger, (b) recrystallization and merger with the matrix grain near the free surface, and (c) grains conduct directional growth to the pore until new grains grow up completely to realize crack healing.