Quality Control Method of 37mn Round Tube Billet with φ280mm

Abstract

The invention discloses a method for controlling the internal quality of a 37Mn circular tube steel casting blank with a phi-280mm production section, and belongs to the field of metallurgy. The method comprises the steps such as smelting in a converter, molten steel refining in an LF furnace, RH vacuum treatment and continuous casting of molten steel. First of all, the purity of the molten steel is improved according to reasonable parameter control in the molten steel smelting stage, and the high-temperature plasticity of the molten steel is improved and the steel grade crack sensitivity is lowered after the molten steel is subjected to titanium microalloying; and then, mold electromagnetic stirring and final electromagnetic stirring are combined in the molten steel pouring stage, so that component and temperature homogenization of the molten steel can be achieved, the shell of the circular tube steel casting blank can grow uniformly, the solidification structure of the circular tube steel casting blank can be effectively improved, the loose level can be raised, the area of an equiaxial crystal region can be enlarged, the compactness of the central region of the circular tube steel casting blank can be effectively improved, the crack defect of the circular tube steel casting blank can be effectively controlled, the surface non-clearing rate can be improved, and the quality of such a rolled product can be controlled well and stably.

Description

technical field [0001] The invention relates to the field of iron and steel metallurgy, in particular to a casting quality control method for producing 37Mn round tube billets with a diameter of 280 mm. Background technique [0002] 37Mn round tube billet steel is mainly used in the production of high-pressure gas cylinders. The chemical composition is: C: 0.35% ~ 0.39%, Si: 0.17% ~ 0.28%, Mn: 1.55% ~ 1.70%, P≤0.020% , S≤0.010%, Cr≤0.20%, Cu≤0.15%, Mo≤0.08%, Ni≤0.20%, Alt: 0.020%~0.040%, and the balance is Fe. The product produced is a refillable mobile steel cylinder, which is used to hold permanent gas or high-pressure liquefied gas, and is widely used in industrial and mining enterprises and national economic industries such as construction, transportation, ocean, aviation, medical treatment and military. Since the gas cylinders are filled with many types of media, and are flammable, explosive, highly toxic or corrosive, and the gas cylinders are refilled and fluid, once...

AI Technical Summary

Problems solved by technology

Mainly due to the high temperature strength of the steel itself, relatively poor toughness and plasticity, low thermal conductivity, large linear expansion coefficient, large internal stress during cooling and solidification, and surface crack defects are prone to occur during continuous casting and straightening

Furthermore, since the slab has a relatively large section and is a round slab, its specific surface area is smaller and the heat transfer efficiency of the slab is lower, and the solidification and cooling are slow. The gradient becomes larger, and the directionality of heat transfer is prominent, which further leads to the development of columnar crystals and the trend of lower equiaxed crystal ratio.