The invention discloses a strengthening and
toughening heat treatment production method of a 50CrVA steel elastic element for a bridge, and belongs to the technical field of steel preparation, and the method comprises the steps of blanking, free
forging, annealing, rough turning,
quenching and
tempering. Free
forging is conducted, the initial stage temperature is 1200 + / -10 DEG C, and the final
forging temperature is 950 + / -10 DEG C; annealing is conducted, the annealing temperature is 860 + / -10 DEG C, heat preservation is conducted for 2.5-3.5 h, furnace cooling is conducted to 400 + / -10 DEG C, and
air cooling is conducted;
quenching is conducted, the
quenching temperature is 915 + / -10 DEG C, the heat preservation time is 20 min, and
oil cooling is conducted; the
tempering temperature is 500 + / -20 DEG C, the heat preservation time is 3 h, and
oil cooling is conducted. The method has the advantages that the
cutting performance of the steel is improved through annealing, and deformation and
cracking during quenching are reduced. Meanwhile, undissolved carbides and aphanitic
martensite structures are obtained, and good
wear resistance is guaranteed. And the
fracture toughness in a medium-temperature
tempering state is improved by quenching at 915 DEG C. And finally,
martensite is promoted to start to decompose through medium-temperature tempering, and quenching
internal stress gradually disappears. But part of
solid solution carbon begins to be separated out in the form of
cementite and can be pinned for
dislocation, and a certain strengthening effect on a matrix is achieved. Meanwhile, due to the fact that the tempering temperature is slightly low, most
alloy elements are still in a matrix, and
solid solution strengthening still plays a main role. And when tempering is carried out within the temperature range, the test steel can keep certain
hardness. Through quenching and tempering processes after annealing, the 50CrVA steel elastic element for the bridge, which is excellent in strength and
hardness and high in
toughness, can be obtained.