Chromium iron grades and applications
Chrome-molybdenum is an iron alloy composed of chromium and iron, serving as a crucial alloying agent in steelmaking. It is categorized by its carbon content, including high-carbon chrome-molybdenum (4-8% carbon), medium-carbon chrome-molybdenum (0.5-4% carbon), low-carbon chrome-molybdenum (0.15-0.50% carbon), ultra-low-carbon chrome-molybdenum (0.06% carbon), super-ultra-low-carbon chrome-molybdenum (carbon less than 0.03%), metallic chromium, silicon-chromium alloys, and more. Common types also include silicon-chromium alloys and nitrided chrome-molybdenum. Chrome-molybdenum is primarily used as an alloying agent in steelmaking, traditionally added during the late refining stage. With advancements in steelmaking processes, such as the AOD method (see off-gas refining), carbon chrome-molybdenum (mainly charge-grade chrome-molybdenum) is used for charging, requiring only low and ultra-low-carbon chrome-molybdenum to adjust composition during the later stage. Therefore, the focus of chrome-molybdenum production is now on refining carbon chrome-molybdenum.
Microcarbon ferrochrome is mainly used in the production of stainless steel, acid-resistant steel, and heat-resistant steel. Smelting methods include electric silicon thermal process and hot blending process, etc.
Medium-carbon low-chromium iron is used in the production of medium-carbon structural steel, chromium steel, and alloy structural steel.
High-carbon chromium iron (including re-refined chromium iron) 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, improving its wear resistance and hardness, while also providing excellent heat resistance for cast iron.
(3) Chromium-containing raw materials used for the production of 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.