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 different carbon contents, including 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 (carbon less than 0.03%), metallic chromium, silicon-chromium alloys, and more. Common types also include silicon-chromium alloys and nitrided chromium iron. Chromium iron is primarily used as an alloying agent in steelmaking, traditionally added during the later stages of steel refining. With advancements in steelmaking processes, such as the use of AOD (see off-line refining) for producing stainless steel and other steel grades, carbon-based chromium iron (mainly charge-grade chromium iron) is loaded into the furnace. This allows for the adjustment of composition with low and micro-carbon chromium iron only in the later stages, making the production of carbon-based chromium iron a key focus in chromium iron manufacturing today.
Microcarbon chromium iron is primarily used in the production of stainless steel, acid-resistant steel, and heat-resistant steel. Refining methods include electro-silicon thermal process and hot-mixing process, among others.
Medium low carbon ferrochrome is used in the production of medium low carbon structural steel, chromium steel, and alloy structural steel.
High carbon chromium iron (including recycled chromium iron) is mainly used for:
(1) Alloying agent for high-carbon ball bearing steel, tool steel, and high-speed steel, enhancing steel's hardenability and increasing 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 producing silicon-chromium alloys and medium, low, and ultra-low carbon ferrochrome by the slagless method.
(4) Chromium-containing raw materials for the electrolytic production of metallic chromium.
(5) Raw material for stainless steel smelting by oxygen blowing method.