Normalization heat treatment method of heavy-gauge low-alloy steel plates

Abstract

The invention provides a normalization heat treatment method of heavy-gauge low-alloy steel plates. The method concretely comprises the steps of heating, heat insulating and cooling. The steel plates prepared through the method of the invention comprise the following components: 0.18% or less of C, 0.50% or less of Si, 1.60% or less of Mn, 0.020% or less of P, 0.010% or less of S, 0.06% or less of Nb, 0.02-0.06% of Al, 0.03% or less of Ti, 0.08% or less of V, and the balance Fe and inevitable impurities. Different heat insulation time and cooling technologies are adopted according to different thicknesses of the steel plates, the heat insulation period is 1.8min / mm and a rolling transmission and collector spray water laminar flow mode is adopted to cool when the thicknesses of the steel plates are equal to or less than 100mm, and the heat insulation period is 2.0-2.2min / mm and a water tank cooling mode is adopted to cool when the thicknesses of the steel plates are greater than 100mm. The normalizing heat treatment technology of the invention allows the cooling intensity and the cooling speed of cores of the steel plates to be improved, the nucleation rate of the steel plates to be improved, tissues in the centers of the steel plates to be refined, the quality of the steel plates to be guaranteed and bad tissues and performances caused by uneven heavy-gauge steel plate cooling to be effectively solved, and is especially suitable for heat treatment technologies of thick steel plates.

Description

technical field [0001] The invention belongs to the technical field of heat treatment of steel plates, and in particular relates to a normalizing heat treatment method for large-thickness low-alloy steel plates. Background technique [0002] Normalizing heat treatment is a heat treatment process in which steel is heated to an appropriate temperature above Ac3 or Acm, and then cooled for a certain period of time to obtain ferrite pearlite structure. Normalizing heat treatment can refine grains, eliminate internal stress, eliminate Widmanstatten structure and Ribbon tissue. Most low-alloy steels are delivered in a normalized state. This heat treatment method is often used in the actual production of this steel type, but the conventional normalizing heat treatment method can only play a good role in thin steel plates. For large-thickness steel plates, after conventional normalizing heat treatment, the improvement effect of grain size, internal stress and harmful structure ...

AI Technical Summary

Problems solved by technology

Most low-alloy steels are delivered in a normalized state. This heat treatment method is often used in the actual production of this steel type, but the conventional normalizing heat treatment method can only play a good role in thin steel plates. For large-thickness steel plates, after conventional normalizing heat treatment, the improvement effect of grain size, internal stress and harmful structure is not obvious, and the physical properties of the steel plate are also greatly affected, especially the performance at the center of the steel plate is very Difficult to meet requirements