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Mechanical Engineers Outlook

Guide for those interested in becoming a mechanical engineer. Includes qualifications, pay, and job duties.

Essentials of Manufacturing

Information, coverage of important developments and expert commentary in manufacturing.

Injection Molding Design Guide

Guide for high quality and cost-effective plastic injection molding.

STEM Career Outlook

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AISI 4340
Category Steel
Class Alloy steel
Type Standard
Common Names Nickel-chromium-molybdenum steel
Designations  Germany: DIN 1.6565
Japan: JIS SNCM 8
United Kingdom: B.S. 2 S 119 , B.S. 3 S 95 , B.S. 3111 Type 6 , B.S. 817 M 40
United States: AMS 5331 , AMS 6359 , AMS 6359B , AMS 6414 , AMS 6414A , AMS 6415 , AMS 6415G , ASTM A322 , ASTM A331 , ASTM A505 , ASTM A519 , ASTM A547 , ASTM A646 , MIL SPEC MIL-S-16974 , SAE J404 , SAE J412 , SAE J770 , UNS G43400

Composition
ElementWeight %
C  0.38-0.43 
Mn  0.60-0.80 
P  0.035 (max) 
S  0.04 (max) 
Si  0.15-0.30 
Cr  0.70-0.90 
Ni  1.65-2.00 
Mo  0.20-0.30 

Mechanical Properties
Properties Conditions 
T (°C)Treatment
Density (×1000 kg/m3) 7.7-8.03 25  
Poisson's Ratio 0.27-0.30 25  
Elastic Modulus (GPa) 190-210 25  
Tensile Strength (Mpa) 744.6  25  annealed at 810°C  more
Yield Strength (Mpa) 472.3 
Elongation (%) 22.0 
Reduction in Area (%) 49.9 
Hardness (HB) 217  25  annealed at 810°C more
Impact Strength (J)
(Izod)
51.1  25  annealed at 810°C  more

Thermal Properties
Properties Conditions 
T (°C)Treatment
Thermal Expansion (10-6/ºC) 11.5  20-100 more oil hardened, tempered 630°C 

Electric Properties
Properties Conditions 
T (°C)Treatment
Electric Resistivity (10-9W-m) 248  20 more  
Glossary
Mechanical Engineers Outlook

Guide for those interested in becoming a mechanical engineer. Includes qualifications, pay, and job duties.

Essentials of Manufacturing

Information, coverage of important developments and expert commentary in manufacturing.

Injection Molding Design Guide

Guide for high quality and cost-effective plastic injection molding.

STEM Career Outlook

Wages, employment opportunities, and growth projections for STEM jobs.