Alloy 718

 

ALLOY TYPE Alloy
ALLOY NAME Alloy 718

Stock Sizes
 
Basic Properties - Mechanical Properties

Solution Annealed Precipation Treated

  
0.2% Proof Stress (N/mm2)[ksi] minimum 862 [125]
Ultimate Tensile Strength (N/mm2)[ksi] minimum 1034 [150]
Elongation (%) minimum 20
Reduction of Area (%) minimum 35
Hardnewss (HBN) 313-354
Charpy Impact Energy[-60C](J) minimum 71(longitudinal)
   



Alloy Features Back to Top
   
Excellent corrosion resistance
   
Resistant to chloride stress corrosion
   
Resistant to sulphide stress cracking
   
High fatigue strength in seawater
   
High Strength and hardness
   
Low magnetic permeability


Chemical Specification Back to Top
Elements Al B C Co Cr Cu Fe Mg Nb Ni P Pb S Si Ta Ti
Minimum 0.4       17   6.6   4.9 50            
Maximum 0.6 0.0.006 0.045 1 21 0.15 19.3 0.35 5.2 55 0.01 0.0005 0.01 0.35 0.05 1.15



Physical Properties Back to Top
Density (Kg.m-1) 82.3
Magnetic Permeability (20°C) <1.002
Curie Temperature (°C) -152
Young’s Modulus (N/mm2) 200 x 10
Specific Heat, 20°C (J.Kg-1.°K-1) 435
Specific Electrical Resistance, 20°C (?Ω.m) 1.25
Thermal conductivity,20°C (W.m-1.°K-1) 11.1
Mean coefficient of thermal expansion, 20-100°C (°K-1) 12.1 x 10



Specifications Back to Top
   

ASTM B637 N07718

API 6A 718

 

Applications Back to Top
 

Oil and Gas Industry:

Wellhead components, Safety Valves, Packers, Fasteners, Clamps, Downhole equipment for corrosive/sour service.

Nuclear Power Plant:

Containment vessels, Valves

Engineering applications between 760°C and cryogenic temperatures

 

 

Machining Advice (hot worked and precipitation hardened alloy) Back to Top

Operation Cutting Speed m/min (ft/min) Feed Rate
mm/rev (in/rev)		 Depth of cut mm (in)
Milling

6-9 (19-29)

0.05-0.15 mm/tooth

0.002-0.006 in/tooth		 0.2-3.0
(0.007-0.12)
Drilling – 6.4mm (1/4”) dia

5-8

(16-25)		 0.02 (0.001)  
Drilling – 12.7mm (1/2”) dia

5-8

(16-25)		 0.08 (0.003)  
Drilling – 25.4mm (1”) dia

5-8

(16-25)		 0.13 (0.005)  
Turning - Roughing

9-15

(29-48)

0.2 – 0.3 (0.008-0.011)

 2.5
(0.1)
Turning - Finishing

15-24

(48-77)

0.08 – 0.20

(0.003-0.008)		 0.25
(0.01)
Tooling Milling/Turning: Carbide (SANDVIK GC 235, SECO T25M) , point angle 118°, chisel angle 120°Drilling: HSS

KEY Features  of the Alloy

Good strength/ductility properties from sub-zero temperatures to over 760°C

Excellent corrosion resistance and fatigue resistance in a wide variety of corrosive chemicals including seawater and industrial acids

Non-magnetic and spark resistant

Excellent resistance to stress corrosion cracking




Alloy Comparisons 718 (aged) NO4400 N05500 S31803 FERRALIUM 255-SD50
0.2% Proof Strength (N/mm2), minimum 827 170 690 450 600
Corrosion Rate (mm.y-1) Seawater <0.01 0.25 0.18 <0.01 <0.01
Corrosion Rate (mm.y-1)
10% sulphuric acid at 80°C		 <0.15 0.06 0.1 0.4 <0.15
Corrosion Rate (mm.y-1)
Boiling 50% nitric acid 		1.5 1.1 <2 >5 >5



 Back to Top
 
Disclaimer
Data in this publication is provided solely for the purposes of distribution of information. Langley Alloys cannot make guarantees with respect to subject matter or accuracy of this information. Langley Alloys specifically disclaims all guarantees, expressed, implied or otherwise, including without limitation, all warranties of merchantability and fitness for a particular purpose. This publication may include technical inaccuracies or typographical errors. If errors are found, please make a notification via e-mail to: info@langleyalloys.com