Chromium iron grades and applications
Chromium iron is an iron alloy composed of chromium and iron, serving as a crucial alloying agent in steelmaking. It is categorized by its carbon content into high-carbon chromium iron (4-8% carbon), medium-carbon chromium iron (0.5-4% carbon), low-carbon chromium iron (0.15-0.50% carbon), micro-carbon chromium iron (0.06% carbon), ultra-micro-carbon chromium iron (less than 0.03% carbon), metallic chromium, silicon-chromium alloys, and more. Common types include silicon-chromium alloys and nitrided chromium iron. Chromium iron is primarily used as an alloying agent in steelmaking, traditionally added during the refining stage of steel production. With advancements in steelmaking processes, such as the AOD method (see off-line refining), carbon-containing chromium iron (mainly charging-grade chromium iron) is used for charging the furnace, which necessitates only the addition of low and micro-carbon chromium iron for composition adjustment in the later stage. Therefore, the focus of chromium iron production has shifted to the production of carbon-containing chromium iron.
Micro-carbon ferrochrome is primarily used in the production of stainless steel, acid-resistant steel, and heat-resistant steel. Smelting methods include electric silicothermic process and hot metal blending, among others.
Medium low carbon ferrochrome is used for producing medium low carbon structural steel, chromium steel, and alloy structural steel.
High-carbon ferrochrome (including recycled ferrochrome) is primarily used for:
(1) Alloying agent for high-carbon ball bearing steel, tool steel, and high-speed steel, enhancing steel's hardenability, wear resistance, and hardness.
(2) Additive for cast iron, enhancing its wear resistance and hardness, while also providing good heat resistance.
(3) Chromium-containing raw materials used for渣less production of silicon-chromium alloys and medium, low, and ultra-low carbon chromium iron.
(4) Chromium-containing raw materials for the electrolytic production of metallic chromium.
(5) Raw material for stainless steel smelting by oxygen blowing method.