Structure and strength of lath martensite

• Published in: Metal science and heat treatment 1999-04, Vol.41 (3-4), p.140-145
• Main Authors: SHTREMEL, M. A, ANDREEV, Yu. G, KOZLOV, D. A
• Format: Article
• Language: English
• Subjects: Alloys; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Metals. Metallurgy; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids
• ISSN: 0026-0673; 1573-8973
• DOI: 10.1007/BF02465797

There is a strong positive correlation between yield strength and both the carbon content and austenite percentage. Martensite is the main structural component of high-strength steels, so its lattice deformation and accompanying strain determine the final morphology (size and shape of martensite crystals, orientation and the state of interfaces), which is of great interest to researchers due to the numerous and valuable practical technical applications. The origin of the structure of lath martensite was clarified by studying quenched single crystals of austenite. Their initial structure does not possess interphase and/or intergrain boundaries, subboundaries and dislocation substructures. The martensite strucure is only determined by the martensitic transformation. Single-lath specimens can be studied in larger ( > 100 mu ), oriented sections to observe the correlation between crystal geometry, morphology, plastic deformation and fracture (as described and discussed in detail in this paper). This analysis provides the rules governing formation of martensite laths. Pole figures for martensite are discussed and analyzed in detail to establish lath morphology. Dislocation densities are calculated to be 7x10 exp 10 cm sub -2 , generated by plastic relaxation (slip). Material discussed: 37KhN3A steel.