High Manganese and Aluminum Steels for the Military and Transportation Industry
Lightweight advanced high strength steels (AHSS) with aluminum contents between 4 and 12 weight percent have been the subject of intense interest in the last decade because of an excellent combination of high strain rate toughness coupled with up to a 17% reduction in density. Fully austenitic cast steels with a nominal composition of Fe-30%Mn-9%Al-0.9%C are almost 15% less dense than quenched and tempered Cr-Mo steels (SAE 4130) with equivalent strengths and dynamic fracture toughness. This article serves as a review of the tensile and high-strain-rate fracture properties associated mainly with silicon additions to this base composition. In the solution-treated condition, cast steels have high work-hardening rates with elongations up to 64%, room-temperature Charpy V-notch (CVN) impact energies up to 200 J, and dynamic fracture toughness over 700 kJ/m2. Silicon additions in the range of 0.59–1.56% Si have no significant effect on the mechanical properties of solution-treated steels but increased the tensile strength and hardness during aging. For steels aged at 530°C to an average hardness of 310 Brinell hardness number, HBW, increasing the amount of silicon from 1.07% to 1.56% decreased the room temperature CVN breaking energy from 92 J to 68 J and the dynamic fracture toughness from 376 kJ/m2 to 265 kJ/m2. Notch toughness is a strong function of phosphorus content, decreasing the solution-treated CVN impact toughness from 200 J in a 0.006% P steel to 28 J in a 0.07% P steel. For age-hardened steels with 1% Si, increasing levels of phosphorus from 0.001% to 0.043% decreased the dynamic fracture toughness from 376 kJ/m2 to 100 kJ/m2.
L. Bartlett and D. C. Van Aken, "High Manganese and Aluminum Steels for the Military and Transportation Industry," JOM Journal of the Minerals, Metals and Materials Society, vol. 66, no. 9, pp. 1770-1784, Minerals, Metals and Materials Society (TMS), Sep 2014.
The definitive version is available at https://doi.org/10.1007/s11837-014-1068-y
Materials Science and Engineering
Keywords and Phrases
Aluminum; Fracture; Hardening; High strength steel; Manganese; Mechanical properties; Phosphorus; Silicon; Steel castings; Steel metallurgy; Strain hardening; Strain rate; Tensile strength; Advanced high strength steel; Austenitic cast steels; Dynamic fracture toughness; Equivalent strength; Properties of solutions; Solution treated conditions; Transportation industry; Work hardening rate; Fracture toughness
International Standard Serial Number (ISSN)
Article - Journal
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01 Sep 2014