如何控制硼在中频炉冶炼成品钢中的含量 How to control Boron Content in Finished Steel

1 ， 中频炉控硼 

I. Boron Control in Induction Furnace

由于中频炉冶炼的工艺以及基于中频炉炼钢生产成本管控，石英砂是中频炉冶炼的主要炉衬材质。中频炉石英质捣打料中添加B2O3作为烧结剂的机理和优势可系统归纳如下：

Due to the smelting process of induction furnaces and the production cost control of steelmaking in induction furnaces, quartz sand is the main lining material for induction furnace smelting. The mechanism theory and advantages of adding B₂O₃ as a sintering aid in quartz (rammed materials) for induction furnaces can be systematically summarized as follows:

1）. 降低烧结温度，促进液相形成

1. Reducing Sintering Temperature and Promoting Liquid Phase Formation

• 低共熔效应：B2O3与SiO2形成的二元体系低共熔点仅372℃，远低于纯石英砂的耐火度（1700℃），使材料在低温下即可通过液相烧结致密化。
• Eutectic Effect: The binary system of B₂O₃ and SiO₂ has a low eutectic point of only 372°C, far lower than the refractoriness of pure quartz sand (1700°C), enabling the material to densify through liquid-phase sintering at low temperatures.
• 早期烧结：372℃时生成的液相加速颗粒间结合，形成初始强度，避免中低温阶段因石英晶型转变（如β→α石英）导致的体积应力破坏。
• Early Sintering: The liquid phase formed at 372°C accelerates inter-particle bonding, forming initial strength and avoiding volume stress damage caused by quartz phase transformation (e.g., β→α quartz) at medium-low temperatures.

2）. 高温黏滞层保护机制

2.High-Temperature Viscous Layer Protection Mechanism

•  黏度调控：B2O3作为玻璃网络形成体，融入SiO2结构后不会显著降低熔体高温黏度（1730℃时黏度仍达2×10⁶ Pa·s），形成高黏滞表面层。
• Viscosity Regulation: As a glass network former, B₂O₃ does not significantly reduce the high-temperature viscosity of the melt after integrating into the SiO₂ structure (viscosity remains as high as 2×10⁶ Pa·s at 1730°C), forming a high-viscosity surface layer
• 抗侵蚀性：高黏度液相层有效阻隔金属熔体的渗透和冲刷，减少化学侵蚀。
• Erosion Resistance: The high-viscosity liquid layer effectively blocks the penetration and scouring of molten metal, reducing chemical erosion
• 结构稳定性：维持玻璃相网络完整性，避免高温下材料软化或流失
• Structural Stability: Maintains the integrity of the glass phase network to prevent material softening or loss at high temperatures..

3）. 抑制石英相变破坏

3）inhibiting Damage of Quartz Phase Transformation 

• 体积膨胀缓冲：石英在573℃（β→α）和1200℃（方石英化）附近发生快速晶型转变，伴随剧烈体积变化（如β→α膨胀+0.82%）。
• Volume Expansion Buffering: Quartz undergoes rapid phase transformations near 573°C (β→α) and 1200°C (cristobalite formation), accompanied by severe volume changes (e.g., β→α expansion +0.82%).
• B2O3液相填充晶界，缓解局部应力，防止鼓包、开裂。
• B₂O₃ liquid phase fills the grain boundaries, relieving local stress and preventing bulging and cracking.
• 减少气孔率，提升中低温区间的结构致密性。
• Reduces porosity and improves structural densification in the medium-low temperature range.

B2O3的引入通过“低温液相烧结-高温高黏滞保护”的双重作用，解决了硅质捣打料中低温易损与高温抗性不足的矛盾，成为中频炉衬材料优化的关键技术路径。

The introduction of B₂O₃ solves the contradiction between the vulnerability of silica rammed materials at medium-low temperatures and insufficient high-temperature resistance through the dual effect of "low-temperature liquid-phase sintering and high-temperature high-viscosity protection," making it a key technical path for optimizing induction furnace lining materials.

二、针对中频炉石英砂炉衬 无硼烧结剂 的性能差异及工艺影响如下：

 II  Performance Differences and Process Impacts of Boron-Free Sintering Aids for Induction Furnace Quartz Sand Linings

1. 无硼烧结剂的局限性

1.Limitations of Boron-Free Sintering Aids

（1）中低温烧结缺陷

(1)Medium-Low Temperature Sintering Defects

• 高温依赖性：无硼烧结剂需在1450℃以上才能有效促进烧结，导致：一次烧结区间（550-1200℃）失效：石英砂未形成足够液相，颗粒结合弱。
• High-Temperature Dependence: Boron-free sintering aids can only effectively promote sintering above 1450°C, which leads to: failure in the primary sintering zone (550-1200°C)---Insufficient liquid phase formation in quartz sand results in weak particle bonding;
• 半烧结层薄：初期结构疏松，抗机械冲击能力差。
•  Thin semi-sintered layer: Loose initial structure leads to poor resistance to mechanical impact.

（2）体积膨胀失控

(2 )Uncontrolled Volume Expansion:

• 石英相变应力集中：573℃（β→α石英）和1200℃（方石英化）时，无硼料无法通过液相缓冲体积膨胀（>5%）。
• Quartz Phase Transformation Stress Concentration: At 573°C (β→α quartz) and 1200°C (cristobalite formation), boron-free materials cannot buffer volume expansion (>5%) through liquid phases.
• 后果：炉衬鼓包、剥落，气孔率上升，耐冲刷性下降。
• Consequences: Lining bulging, spalling, increased porosity, and reduced erosion resistance.

（3）首炉烧结不足导致的熔炼风险问题：

（3） Melting Risks Caused by Inadequate Initial Sintering

• 重废钢/压块料冲击：未充分烧结的炉衬易被高密度炉料（如重废）撞击破碎，或引发炉料上浮。
• Impact of heavy scrap/ briquettes: Insufficiently sintered linings are easily broken by high-density charge materials (e.g., heavy scrap) or cause charge floating

• 粒子钢/破碎料适应性：轻质炉料对未烧结层影响较小，可作为首炉优选。
• Adaptability to particle steel/ crushed materials: Lightweight charge materials have less impact on unsintered layers and can be preferred for the initial heat.

2. 无硼炉衬的工艺补偿措施

2.Process Compensation Measures for Boron-Free Linings

（1）使用无硼料，需通过工艺调整弥补缺陷：

（1）When using boron-free materials, we need use process adjustments to compensate for defects:

• 阶梯式升温：首炉前进行阶梯烘烤（1200℃、1400-1500℃各保温1-2小时），强制促进烧结。
• Stepped heating: we do stepped baking before the initial heat (1200°C, 1400-1500°C, each with 1-2 hours of holding) to force sintering.
• 炉料选择：首炉仅用破碎料/粒子钢，避免重废冲击。第二炉后再逐步加入压块/重废。
• Charge selection: we use only crushed materials/ particle steel for the initial heat to avoid heavy scrap impact, then gradually add briquettes/ heavy scrap after the second heat.

（2）， 钢包（大包）炉衬选用

（2）Selection of Ladle (large ladle) Linings

      由于钢包不过精炼，没有升温过程，整个钢包不具备石英砂无硼炉料烧结过程。 不能使用石英砂无硼料，做钢包打结炉衬。 可以考虑，耐火砖或者耐火浇注料。 

Since ladles do not undergo refining and have no temperature-raising process, the entire ladle does not allow for the sintering process of boron-free quartz sand lining materials. Quartz sand boron-free materials cannot be used for ladle rammed linings.  Instead,refractory bricks or refractory castables can be considered.

（3） ， 中间包炉衬选用

（3）Selection of Tundish Linings

      中间包工作温度1530-1580 ， 中包工作温度低于钢包工作温度，无硼石英砂捣打料更加无法完成烧结过程，因此中间包工作层需要采用，以树脂为结合剂的工作层用料，由于树脂的在300以上可以形成碳链（硬化），故此适合使用在中包工作层 。

The working temperature of tundishes is 1530-1580°C, which is lower than that of ladles. Boron-free quartz sand rammed materials cannot complete the sintering process. Therefore, the tundish working layer should use resin-bonded materials. As resins can form carbon chains (hardening) above 300°C, they are suitable for tundish working layers.

树脂结合打结料由于是树脂结合，其形成的硬化层是无法完成完全烧结，因此树脂结合打结料在完成一个循环的工作后，需要对中间包工作层进行完全更换。树脂结合打结料不能重复使用。

   Since resin-bonded rammed materials form a hardened layer through resin bonding without complete sintering, the tundish working layer needs to be fully replaced after one cycle of operation. Resin-bonded rammed materials cannot be reused.