Jul 5 2013
	Topics Covered
	Introduction
	Chemical Composition
	Physical Properties
	Mechanical Properties
	Thermal Properties
	Other Designations
	Fabrication and Heat Treatment
	     Heat treatment
	     Annealing
	     Aging
	Applications
	Introduction
	Grade 28 Ti-3Al-2.5V-0.1Ru alloy is a ruthenium-enhanced version of grade Ti-3Al-2.5V with similar physical and mechanical properties. Ruthenium provides this alloy with improved corrosion resistance. This alloy provides high resistance to dilute reducing acids and crevice corrosion in hot halide (brine) solution. It has been approved for use in sour service under the NACE MR-01-75 Standard.
	The following sections will discuss in detail about grade 28 Ti-3Al-2.5V-0.1Ru alloy.
	Chemical Composition
	The chemical composition of grade 28 Ti-3Al-2.5V-0.1Ru alloy is outlined in the following table.
	
		
			| 
				Element | 
			
				Content (%) | 
		
		
			| 
				Titanium, Ti | 
			
				92.435 - 95.42 | 
		
		
			| 
				Aluminum, Al | 
			
				2.5 - 3.5 | 
		
		
			| 
				Vanadium, V | 
			
				2-3 | 
		
		
			| 
				Ruthenium, Ru | 
			
				0.080 - 0.14 | 
		
		
			| 
				Iron, Fe | 
			
				≤ 0.25 | 
		
		
			| 
				Oxygen, O | 
			
				≤ 0.15 | 
		
		
			| 
				Carbon, C | 
			
				≤ 0.080 | 
		
		
			| 
				Nitrogen, N | 
			
				≤ 0.030 | 
		
		
			| 
				Hydrogen, H | 
			
				≤ 0.015 | 
		
		
			| 
				Other, each | 
			
				≤ 0.10 | 
		
		
			| 
				Other, total | 
			
				≤ 0.40 | 
		
	
	Physical Properties
	The physical properties of grade 28 Ti-3Al-2.5V-0.1Ru alloy are tabulated below.
	
		
			| 
				Properties | 
			
				Metric | 
			
				Imperial | 
		
		
			| 
				Density | 
			
				4.48 g/cm3 | 
			
				0.161 lb/in3 | 
		
		
			| 
				Melting point | 
			
				1700°C | 
			
				3092°F | 
		
	
	Mechanical Properties
	The following table shows mechanical properties of grade 28 Ti-3Al-2.5V-0.1Ru alloy.
	
		
			| 
				Properties | 
			
				Metric | 
			
				Imperial | 
		
		
			| 
				Tensile strength | 
			
				620 MPa | 
			
				90 ksi | 
		
		
			| 
				Yield strength | 
			
				483 MPa | 
			
				70 ksi | 
		
		
			| 
				Poisson's ratio | 
			
				0.34 | 
			
				0.34 | 
		
		
			| 
				Elastic modulus | 
			
				107 GPa | 
			
				15519 ksi | 
		
		
			| 
				Hardness (HV) | 
			
				260-320 | 
			
				260-320 | 
		
	
	Thermal Properties
	The thermal properties of grade 28 Ti-3Al-2.5V-0.1Ru alloy are tabulated below.
	
		
			| 
				Properties | 
			
				Metric | 
			
				Imperial | 
		
		
			| 
				Thermal conductivity | 
			
				7.9 W/mK | 
			
				54.7 BTU in/hr.ft².°F | 
		
	
	Other Designations
	Equivalent materials to grade 28 Ti-3Al-2.5V-0.1Ru alloy are as follows:
	- 
		ASTM B265
 
	- 
		ASTM B337
 
	- 
		ASTM B338
 
	- 
		ASTM B381
 
	- 
		ASTM B861
 
	- 
		ASTM B862
 
	Fabrication and Heat Treatment
	Heat treatment
	Grade 28 Ti-3Al-2.5V-0.1Ru alloy can be solution treated at 870-925°C (1598-1697°F) for 15-20 h and then water quenched.
	Annealing
	Annealing of this material can be performed by heating to 595-760°C (1103-1400°F) for 1-3 h and then air-cooled.
	Aging
	Aging of grade 28 Ti-3Al-2.5V-0.1Ru alloy can be performed at 480-510°C (896-950°F) for 2-8 h and then air-cooled.
	Applications
	Grade 28 Ti-3Al-2.5V-0.1Ru alloy finds use in:
	- 
		Seawater applications
 
	- 
		High crevice corrosion temperature environment.