What functions does manganese metal ingot have in steelmaking?

Manganese ingots are made with high-purity manganese (Mn) as the core component:

 Composition range: Mn≥95% (Mn95 grade), Mn≥97% (Mn97 grade), Mn≥99% (Mn99 grade), impurities C≤0.1%, S≤0.05%, P≤0.04%, Fe≤2.0%;

 Physical properties: Melting point 1244℃, density 7.43g/cm³, silvery-gray lumps (10-50mm), relatively brittle at room temperature, highly chemically active at high temperatures, with reducing power second only to calcium, aluminum, and silicon;

 Core advantages: Strong synergistic effect in deoxidation and desulfurization, high alloying efficiency, cost 30%-40% lower than silicon-calcium alloys, suitable for large-scale steelmaking production.

(1) Deoxidation Function: Mild Reduction and Inclusion Optimization

Manganese metal ingots are commonly used as a "mild deoxidizer" in steelmaking, avoiding excessive deoxidation that could cause the molten steel to boil, while simultaneously optimizing the morphology of inclusions:

Core reaction mechanism:

Mn + FeO → MnO + Fe (spontaneous reaction in molten steel at 1500-1600℃). The generated MnO has a lower density than the molten steel and is easily floated and removed with the slag; furthermore, MnO can form low-melting-point composite slag (melting point 1200-1300℃) with SiO₂ and Al₂O₃, further improving the removal efficiency of deoxidation products;

Quantitative deoxidation effect:

Adding 0.2%-0.5% (Mn97 grade) can reduce the oxygen content of molten steel from 80-100ppm to 40-60ppm, achieving a deoxidation efficiency of... 37.5%-50%;

Comparative advantages:

Weaker reducing power than aluminum and silicon, preventing violent boiling of molten steel, while increasing the deoxidation efficiency of silicon and aluminum by 10%-15%, avoiding inclusion aggregation caused by using silicon and aluminum alone;

(2) Desulfurization function: Stable desulfurization and hot brittleness suppression

Manganese metal lumps reduce the sulfur content in steel by forming stable compounds with sulfur, avoiding hot brittleness defects:

Core reaction mechanism:

Mn + FeS → MnS + Fe, the generated MnS has a melting point of 1610℃ and a solubility of only 0.0003% (in molten steel), almost insoluble in molten steel, easily floating to the slag for removal;

Quantitative desulfurization effect:

Adding 0.3%-0.8% (Mn97 grade) can reduce the sulfur content of molten steel from 0.05%-0.08% to 0.02%-0.03%, achieving a desulfurization rate of... 40%-75%; Core Value: Effectively suppresses hot brittleness in steel, reducing the cracking rate during hot working (rolling, forging) from 1.2% to 0.3%, and improving processing plasticity;

Synergistic Advantages:

When used in conjunction with calcium silicon alloys, the desulfurization rate can be increased to over 80%, meeting the production requirements of low-sulfur steel (S≤0.01%).

(3) Alloying Function: Performance Enhancement and Microstructure Optimization

Mandac is one of the most important alloying elements in steelmaking. Through solid solution strengthening and microstructure refinement, it comprehensively improves the mechanical properties of steel:

 Core Strengthening Mechanism:

Solid Solution Strengthening: Manganese atoms integrate into the ferrite and pearlite lattices, causing lattice distortion, hindering dislocation movement, and improving the strength and hardness of the steel;

Microstructure Refinement: Manganese lowers the phase transformation temperature of steel, refines pearlite grains, and improves the toughness and wear resistance of the steel;

 Quantitative Performance Improvement:

Low Alloy Structural Steel (Q355): Adding 0.8%-1.7% Mn97 grade manganese ingots increases tensile strength from 345MPa to 410-450MPa, yield strength increases by 20%-30%, and impact toughness (-20℃) ≥60J/cm²;

Wear-Resistant Steel (NM450): Adding 1.5%-2.0% manganese ingots, combined with carbon elements to form Mn₃C The hard phase increases the steel's hardness (HRC) from 25 to 45-50, and improves wear resistance by 40%-60%.

Spring steel (60Si2Mn): Adding 0.7%-1.0% manganese ingots improves the steel's hardenability and elastic limit, increasing fatigue life by 30%-50%.

 Production of Low-Alloy High-Strength Steel

Suitable steel grades: Q355, Q420, Q690, etc., accounting for more than 40% of the total application of manganese ingots;

Process compatibility: Added in the later stage of converter/electric furnace steelmaking (10-50mm block shape), addition amount 0.5%-1.7%, manganese recovery rate 90%-95%;

 Production of Wear-Resistant Steel and Steel for Engineering Machinery

Suitable steel grades: NM360, NM450, 15MnVN, etc.;
Quantitative parameters: Add 1.0%-2.0% Mn97 grade manganese ingots, the tensile strength of the steel is ≥1000MPa, and the wear resistance meets the requirements of engineering machinery (excavator bucket teeth, crusher liners);

 Production of Spring Steel and Bearing Steel

Suitable steel grades: 60Si2Mn, 50CrVA, GCr15 =etc;

Core requirements: Mn99 grade high-purity metallic manganese ingots (impurities C≤0.05%, P≤0.03%) must be selected to avoid impurities affecting the elasticity and fatigue life of steel;

Quantitative effect: Adding 0.7%-1.2% Mn99 grade products, the elastic limit of spring steel ≥1200MPa, and the contact fatigue life of bearing steel ≥10⁷ times;

 Upgrading production of ordinary carbon steel

Suitable steel grades: Q235, Q255, etc.;

Application value: Adding 0.2%-0.5% Mn95 grade metallic manganese ingots can increase the tensile strength of ordinary carbon steel from 235MPa to 270-290MPa, meeting the strength requirements of building and mechanical structural components;

(1) Core grade and application adaptation table

(2) Core selection principle

Performance priority: High-end steel (spring steel, bearing steel) Mn99 grade ensures high purity and low impurities;
Cost balance: Mn97 grade is selected for ordinary steel and low alloy steel to balance performance and cost;
Cost priority: Mn95 grade is selected for low-requirement carbon steel to control raw material costs;