A Review of the Physical and Mechanical Properties of a Cast High Strength and Lightweight Fe-Mn-Al-C Steel
Lightweight, age-hardenable steels in the Fe-Mn-Al-C system are currently being developed as an alternative to quenched and tempered steels. At a composition of Fe-30Mn-9Al- 1Si-0.9C-0.5Mo, all compositions in weight percent, these alloys are almost 15% less dense than traditional steels and are completely austenitic when solution treated above 950° C. Recent research has focused on variations of this base composition and this paper serves as a compilation of the associated mechanical and physical properties of mostly cast materials. In the solution treated condition, lightweight steels have high work hardening rates and excellent ductility with elongations up to 64%. Tensile strength depends on the degree of age-hardening with cast tensile strengths greater than 1,000 MPa and wrought strengths as high as 1,160 MPa. In the aged condition, high strain rate compression tests have recorded yield strengths at 1,334 MPa with work hardening to ultimate strengths of 1,650 MPa. Notch toughness in these steels is mainly a function of the amount of phosphorus, inclusion content, and age-hardening. First principles calculations show that phosphorus substitutes for aluminum in the k-carbide structure and lowers the cleavage energy by 45%. However, with proper steelmaking practice and elimination of phosphorus to levels below 0.006%, this alloy attains Charpy 'V' notch (CVN) breaking energies of 39 J at -40° C and room temperature dynamic fracture toughness values of up to 420 kJ/m2 in the aged condition. Measured physical properties such as thermal conductivity and thermal expansion were close to those reported for high manganese austenitic steels. The modulus of elasticity was measured in hot rolled plate and found to increase slightly from 156 to 161 MPa with increased aging time.
L. Bartlett et al., "A Review of the Physical and Mechanical Properties of a Cast High Strength and Lightweight Fe-Mn-Al-C Steel," Proceedings of the Materials Science and Technology Conference and Exhibition (2010, Houston, TX), vol. 3, pp. 1941 - 1953, ASM International, Oct 2010.
Materials Science and Technology Conference and Exhibition (2010: Oct. 17-21, Houston, TX)
Materials Science and Engineering
Peaslee Steel Manufacturing Research Center
Keywords and Phrases
Aging time; Austenitic; Base composition; C-steel; C-systems; Carbide structure; Cast material; Dynamic fracture toughness; Fe-Mn-Al-C steel; First-principles calculation; High manganese austenitic steel; High strain rates; High strength; Hot-rolled; Inclusion content; Lightweight steel; Mechanical and physical properties; Modulus of elasticity; Notch toughness; Quenched and tempered steel; Room temperature; Solution treated conditions; Steelmaking practice; Ultimate strength; Weight percent; Work hardening rate; Yield strength, Aluminum; Austenite; Carbides; Compression testing; Dynamics; Fracture toughness; High strength steel; Iron alloys; Manganese; Mechanical properties; Molybdenum; Phosphorus; Physical properties; Strain hardening; Strain rate; Tensile strength; Thermal expansion; Age hardening
International Standard Book Number (ISBN)
Article - Conference proceedings
© 2010 ASM International, All rights reserved.
01 Oct 2010