High Chrome Cast Iron

High-chromium alloys are alloys composed of chromium as a base and other elements. They possess excellent oxidation resistance and resistance to corrosion from high-sulfur fuels, diesel fuels, and seawater. High-chromium alloys are widely used in turbine blades and guide vanes of jet engines.

 

High-chromium cast iron is short for high-chromium white cast iron, a type of wear-resistant cast iron containing 12%-28% chromium. Due to its unique microstructure, high-chromium cast iron castings exhibits significantly higher toughness, high-temperature strength, heat resistance, corrosion resistance, and wear resistance compared to ordinary cast iron and alloy steel castings.

 

High-chromium cast iron is a multi-phase alloy with Fe, Cr, and C as its basic components. The matrix of freshly solidified high-chromium cast iron is austenite, which becomes stable only at high temperatures and is saturated with elements such as C and Cr. As the temperature decreases, the austenite undergoes a transformation. Under normal conditions, high-chromium cast iron exhibits a multiphase structure dominated by austenite. This structure allows the material to better utilize its inherent potential at high temperatures.

 

The large addition of chromium transforms the M3C type carbides in white cast iron into M7C3 type carbides. These alloy carbides are very hard, giving high-chromium cast iron excellent wear resistance. On the other hand, during the solidification process, the M7C3 type carbides are distributed in rod-like isolated forms, which improves the toughness of high-chromium cast iron to a certain extent.

 

Typical High Chrome Alloy Castings

 

 

 

 

 

Chemical Compositions of High Chrome Alloys

 

No.	Alloy Designation	Alloy classification	Main element content (mass fraction) / %
			C	Si	Mn	Cr	Mo	Ni	W	Cu	S	P
1	BTMNi4Cr2-DT	Nickel-chromium alloy wear-resistant white cast iron	2.5-3.0	≤0.8	≤0.8	1.5-3.0	-	3.0-5.5	-	-	≤0.1	≤0.1
2	BTMNi4Cr2-GT		3.0-3.6	≤0.8	≤0.8	1.5-3.0	-	3.0-5.5	-	-	≤0.1	≤0.1
3	BTMCr9Ni5-DT		2.4-2.8	1.5-2.2	0.2-0.8	8.0-10.0	-	4.0-5.5	-	-	≤0.06	≤0.06
4	BTMCr9Ni5-ZT		2.5-3.5	1.5-2.5	0.3-0.8	8.0-10.0	-	4.5-6.5	-	-	≤0.06	≤0.06
5	BTMCr9Ni5-GT		3.2-3.6	1.5-2.2	0.2-0.8	8.0-10.0	-	4.0-5.5	-	-	≤0.06	≤0.06
6	BTMCr2	Chromium alloy wear-resistant white cast iron	2.1-3.6	≤1.5	≤2	1.0-3.0	-	-	-	-	≤0.10	≤0.10
7	BTMCr8		2.1-3.6	1.5-2.2	≤2	7.0-10.0	≤3	≤1.0	-	≤1.2	≤0.06	≤0.06
8	BTMCr12-DT		1.1-2.0	≤1.5	≤2	10.0-14.0	≤3	≤2.5	-	≤1.2	≤0.06	≤0.06
9	BTMCr12-GT		2.0-3.6	≤1.5	≤2	10.0-14.0	≤3	≤2.5	-	≤1.2	≤0.06	≤0.06
10	BTMCr15		2.0-3.8	≤1.2	≤2	14.0-18.0	≤3	≤2.5	-	≤1.2	≤0.06	≤0.06
11	BTMCr20		2.0-3.6	≤1.2	≤2	18.0-23.0	≤3	≤2.5	-	≤1.2	≤0.06	≤0.06
12	BTMCr26		2.0-3.5	≤1.2	≤2	23.0-30.0	≤3	≤2.5	-	≤1.2	≤0.06	≤0.06
13	BTMCr35		3.0-5.0	≤1.0	1.0-3.0	30.0-40.0	≤1.5	≤1.0	-	≤1.2	≤0.06	≤0.06
14	BTMCr12Mn2W	Chromium-manganese-tungsten alloy wear-resistant white cast iron	2.0-2.8	0.3-1.0	2.0-2.5	10.0-16.0	-	-	0.3-1.0	-	≤0.06	≤0.08
15	BTMCr12Mn3W		2.0-2.8	0.3-1.0	2.5-3.5	10.0-16.0	-	-	1.0-1.5	-	≤0.06	≤0.08
16	BTMCr18Mn2W		2.8-3.5	0.3-1.0	2.0-2.5	16.0-22.0	-	-	0.3-1.0	-	≤0.06	≤0.08
17	BTMCr18Mn3W		2.8-3.5	0.3-1.0	2.5-3.5	16.0-22.0	-	-	1.0-1.5	-	≤0.06	≤0.08