Jun 17 2013
	Topics Covered
	Introduction
	Chemical Composition
	Physical Properties
	Mechanical Properties
	Thermal Properties
	Other Designations
	Introduction
	In alloy steels, alloying elements are added in lower quantities to improve its strength and hardenability or in larger quantities to achieve properties like extreme temperature stability and corrosion resistance.
	AISI 8642 alloy steel is a nickel-chromium-molybdenum steel. The following section will discuss in detail about AISI 8642 alloy steel.
	Chemical Composition
	The chemical composition AISI 8642 alloy steels is outlined in the following table.
	
		
			| 
				Element | 
			
				Content (%) | 
		
		
			| 
				Iron, Fe | 
			
				96.585 - 97.93 | 
		
		
			| 
				Chromium, Cr | 
			
				0.75 - 1.2 | 
		
		
			| 
				Manganese, Mn | 
			
				0.65 - 1.1 | 
		
		
			| 
				Carbon, C | 
			
				0.37 - 0.44 | 
		
		
			| 
				Molybdenum, Mo | 
			
				0.15 - 0.3 | 
		
		
			| 
				Silicon, Si | 
			
				0.15 - 0.3 | 
		
		
			| 
				Sulfur, S | 
			
				≤0.040 | 
		
		
			| 
				Phosphorous, P | 
			
				≤0.035 | 
		
	
	Physical Properties
	The following table shows the physical properties of AISI 8642 alloy steels.
	
		
			| 
				Properties | 
			
				Metric | 
			
				Imperial | 
		
		
			| 
				Density | 
			
				7.85 g/cm3 | 
			
				0.284 lb/in3 | 
		
	
	Mechanical Properties
	The mechanical properties of AISI 8642 alloy steels are displayed in the following table.
	
		
			| 
				Properties | 
			
				Metric | 
			
				Imperial | 
		
		
			| 
				Tensile strength | 
			
				903 MPa | 
			
				131000 psi | 
		
		
			| 
				Yield strength | 
			
				738 MPa | 
			
				107000 psi | 
		
		
			| 
				Modulus of elasticity | 
			
				205 GPa | 
			
				29700 ksi | 
		
		
			| 
				Bulk modulus | 
			
				140 GPa | 
			
				20300 ksi | 
		
		
			| 
				Shear modulus | 
			
				80 GPa | 
			
				11600 ksi | 
		
		
			| 
				Poisson’s ratio | 
			
				0.29 | 
			
				0.29 | 
		
		
			| 
				Elongation at break | 
			
				20.40% | 
			
				20.40% | 
		
		
			| 
				Hardness, Brinell | 
			
				269 | 
			
				269 | 
		
		
			| 
				Hardness, Vickers | 
			
				284 | 
			
				284 | 
		
		
			| 
				Hardness, Knoop | 
			
				294 | 
			
				294 | 
		
		
			| 
				Hardness, Rockwell C | 
			
				27 | 
			
				27 | 
		
		
			| 
				Hardness, Rockwell B | 
			
				99 | 
			
				99 | 
		
		
			| 
				Machinability | 
			
				65 | 
			
				65 | 
		
	
	Thermal Properties
	The thermal properties of AISI 8642 alloy steels are given in the following table
	
		
			| 
				Properties | 
			
				Metric | 
			
				Imperial | 
		
		
			| 
				Thermal conductivity | 
			
				46.6 W/mK | 
			
				323 BTU.in/hrft².°F | 
		
	
	Other Designations
	Other designations that are equivalent to AISI 8642 alloy steels include the following.
	- 
		ASTM A322
 
	- 
		ASTM A331
 
	- 
		ASTM A505
 
	- 
		ASTM A519
 
	- 
		SAE J404
 
	- 
		SAE J412
 
	- 
		SAE J770