CN-121992212-A - Smelting method for solving macrosegregation of high boron steel

Abstract

The invention discloses a smelting method for solving macrosegregation of high-boron steel, and belongs to the technical field of high-end special steel metallurgy. The method comprises the steps of firstly sealing titanium diboride (TiB 2 ) powder in a metal bag, adding the powder into a vacuum induction furnace together with furnace charge, realizing high yield of boron and titanium elements and liquid phase extreme homogenization through the synergistic effect of electromagnetic stirring and bottom blowing argon, eliminating segregation sources from sources, and carrying out deep purification and directional solidification on uniform electrodes through an electroslag remelting process to finally obtain the high boron steel cast ingot with no macrosegregation, tiny dispersion of tissues and high purity. The invention solves the technical problems of low yield, serious segregation and uneven performance of the high boron steel, and the process flow is suitable for industrialized mass production.

Inventors

• XU YUBIN
• WU XIAOLONG
• SONG HONGLONG
• MA CHAO
• WANG YUFEI
• GUO RUIHUA
• LI RUIJIE
• AN ZHIGUO
• QI ZIYANG
• ZHAO PEIYI
• LV XIAONING

Assignees

• 河北河钢材料技术研究院有限公司
• 河钢集团有限公司
• 河钢股份有限公司

Dates

Publication Date

20260508

Application Date

20260210

Claims (10)

1. 1. A smelting method for solving the macrosegregation of high boron steel is characterized by comprising the following steps: s1, sealing titanium diboride powder in a metal bag, loading the titanium diboride powder into a vacuum induction furnace along with metal furnace charge for smelting, refining by the synergistic effect of electromagnetic stirring and bottom blowing inert gas after smelting, and pouring to obtain a consumable electrode; s2, electroslag remelting is carried out on the consumable electrode, and the high boron steel cast ingot is obtained.
2. 2. The smelting method for solving the macrosegregation of high boron steel according to claim 1, wherein in the step S1, the granularity of titanium diboride powder is 10-150 μm, the metal package is made of low carbon steel or pure iron sheet, and the thickness of a shell layer is 0.5-1.5 mm.
3. 3. The smelting method for solving the macrosegregation of the high boron steel, which is disclosed in claim 1, is characterized in that in the step S1, a metal coating is arranged at the middle lower part of furnace burden in a crucible of a vacuum induction furnace, and after the furnace pressure is lower than 10Pa, the metal coating is vacuumized and heated to 1550-1650 ℃ to enable the metal coating to be completely melted.
4. 4. The smelting method for solving the macrosegregation of the high boron steel, which is disclosed in claim 1, is characterized in that in the step S1, the bottom blowing inert gas is high-purity argon, the flow is 5-15L/min, and the heat preservation time of collaborative refining is 10-20 minutes.
5. 5. A smelting method for solving macrosegregation of high boron steel as set forth in claim 1, wherein in the step S1, the casting is conducted under the protection of inert gas.
6. 6. The smelting method for solving the macrosegregation of the high boron steel, as set forth in claim 1, wherein in the step S2, the electroslag remelting is premelted slag composed of CaO, al 2 O 3 and MgO, wherein the CaO content is 50% -60%, the Al 2 O 3 content is 20% -30% and the MgO content is 5% -10% by mass.
7. 7. The smelting method for solving the macrosegregation of the high boron steel, which is disclosed in claim 1, is characterized in that in the step S2, the electroslag remelting process is carried out under a protective atmosphere by adopting a steady-state remelting system, the melting speed is controlled to be 3.5-6.5 kg/min, and after the remelting is finished, the steel ingot is slowly cooled to be below 300 ℃ at a cooling rate of less than or equal to 30 ℃/h and then is demolded.
8. 8. The smelting method for solving the macrosegregation of the high boron steel, as set forth in any one of claims 1 to 7, is characterized in that the yield of boron and titanium elements of the high boron steel ingot prepared by the method is not less than 95%.
9. 9. The smelting method for solving the macrosegregation of high boron steel, as set forth in any one of claims 1 to 7, characterized in that the boron element components of different parts of the high boron steel ingot prepared by the method are extremely bad and less than or equal to 0.05wt%.
10. 10. A high boron steel ingot prepared by the smelting method for solving the macrosegregation of high boron steel according to any one of claims 1-9, which is characterized in that the yield of boron and titanium elements in the ingot is not less than 95%, and the difference of boron elements at different parts of the ingot is not more than 0.05wt%.

Description

Smelting method for solving macrosegregation of high boron steel Technical Field The invention belongs to the technical field of high-end special steel metallurgy, and particularly relates to a smelting method for solving macrosegregation of high-boron steel. Background The high boron steel has irreplaceable functions in the fields of nuclear industry, aerospace and wear-resistant parts due to the excellent neutron absorption section, high temperature strength and wear resistance. However, the nature of boron presents a significant challenge to its smelting. The existing solutions all have obvious defects: The traditional alloy adding method has the inherent defects of 1) extremely low yield and instability, and currently, boron iron (Fe-B) or boron carbide (B 4 C) is widely adopted as a boron source in the industrial production. The chemical property of the boron element is extremely active, so that the boron element is extremely easy to react with oxygen and nitrogen to burn out in the high-temperature smelting process and volatilize in a large amount, the yield of the boron is extremely low (usually 30% -50%), the fluctuation of different heats is huge, and the accurate control of components is extremely difficult. 2) Severe macrosegregation boron is an extremely strong negative segregation element. The traditional alloy additive has lower melting point and high dissolution speed, and can form a high concentration zone in the local instant of molten steel. In the subsequent solidification process, boron is continuously pushed away by the solidification front, and finally is intensively concentrated in the central and upper areas of the cast ingot to form a serious macrosegregation zone. The structure and performance of different positions of the cast ingot are huge, the cast ingot is easy to crack during subsequent hot working (forging and rolling), the performance of the finished product is unstable, and the yield is extremely low. 3) The material properties are deteriorated by segregation, which results in the formation of a continuous or semi-continuous network of brittle boride at grain boundaries, severely compromising the toughness, plasticity and fatigue properties of the steel. In order to solve the segregation problem, a powder metallurgy method is adopted, namely, boron powder and iron-based powder are mixed and then pressed and sintered to form the powder. However, the Powder Metallurgy (PM) method has problems of long process flow, huge equipment investment (such as powder making and hot isostatic pressing equipment), high cost of powder raw materials, and the like. Most importantly, the density of the product is generally lower than that of a fused casting, microscopic pores and original grain boundaries exist, so that the mechanical properties (particularly impact toughness and fatigue strength) are obviously different from those of the fused casting material, and the product is difficult to apply to key structural components with extremely high requirements on reliability. In addition, the PM process is severely limited in the production of large-size, large tonnage billets. Therefore, the development of the high boron steel smelting method which can be compatible with high yield, extremely uniformity and full densification and is suitable for industrial mass production is a key point for breaking through the engineering application bottleneck. Disclosure of Invention The invention aims to provide a smelting method for solving the problem of macrosegregation of high boron steel. The method overcomes the double defects of the traditional alloy adding method and the powder metallurgy method, and provides the VIM-ESR duplex smelting method which has reasonable process flow, high boron and titanium yield, can fundamentally eliminate macrosegregation and obtain the high boron steel cast ingot with ultrahigh uniformity and purity. A smelting method for solving the macrosegregation of high boron steel comprises the following steps: s1, sealing titanium diboride powder in a metal bag, loading the titanium diboride powder into a vacuum induction furnace along with metal furnace charge for smelting, refining by the synergistic effect of electromagnetic stirring and bottom blowing inert gas after smelting, and pouring to obtain a consumable electrode; s2, electroslag remelting is carried out on the consumable electrode, and the high boron steel cast ingot is obtained. In the step S1, the granularity of titanium diboride powder is 10-150 mu m, the metal package is made of low carbon steel or pure iron sheet, and the thickness of a shell layer is 0.5-1.5 mm. In the step S1, a metal coating is arranged at the middle lower part of furnace burden in a crucible of a vacuum induction furnace, and is vacuumized until the pressure in the furnace is lower than 10Pa, and then heated to 1550-1650 ℃ to be completely melted. In the step S1, the bottom blowing inert gas is high-purity argon, the flow is 5-15L/min,