Comparison of mechanical properties of martensite/ferrite and bainite/ferrite dual phase 4340 steels

Saeidi, Navid; Ekrami, A.

doi:10.1016/j.msea.2009.06.057

Cited by 116 publications

(74 citation statements)

References 9 publications

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“…Besides, in some voids the MnS inclusions were observed for all heat treatment conditions (Fig. 16), which could be a site for void formation [6,28].…”

Section: Fractographymentioning

confidence: 93%

“…Traditional microstructures of DP steels consist of polygonal ferrite and martensite. To satisfy custom requirements, ferrite-bainite-martensite and ferrite-bainite steels were produced in order to modify mechanical properties: bainite instead of martensite were shown to improve formability with a little decrease of strength [5][6][7]. The effect of martensite fraction, distribution and martensite region size, and the effect of ferrite fraction and grain size on mechanical behaviour of DP steels have been intensively studied.…”

Section: Introductionmentioning

confidence: 99%

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Microstructures and mechanical properties of dual phase steel produced by laboratory simulated strip casting

et al. 2015

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Conventional dual phase (DP) steel (0.08C-0.81Si-1.47Mn-0.03Al wt.%) was manufactured using simulated strip casting schedule in laboratory. The average grain size of prior austenite was 117. ±. 44. μm. The continuous cooling transformation diagram was obtained. The microstructures having polygonal ferrite in the range of 40-90%, martensite with small amount of bainite and Widmanstätten ferrite were observed, leading to an ultimate tensile strength in the range of 461-623. MPa and a corresponding total elongation in the range of 0.31-0.10. All samples exhibited three strain hardening stages. The predominant fracture mode of the studied steel was ductile, with the presence of some isolated cleavage facets, the number of which increased with an increase in martensite fraction. Compared to those of hot rolled DP steels, yield strength and ultimate tensile strength are lower due to large ferrite grain size, coarse martensite area and Widmanstätten ferrite. Abstract: Conventional dual phase (DP) steel (0.08C-0.81Si-1.47Mn-0.03Al wt. %) was manufactured using simulated strip casting schedule in laboratory. The average grain size of prior austenite was 117±44 μm. The continuous cooling transformation diagram was obtained. The microstructures having polygonal ferrite in the range of 40-90 %, martensite with small amount of bainite and Widmanstätten ferrite were observed, leading to an ultimate tensile strength in the range of 461 -623 MPa and a corresponding total elongation in the range of 0.31 -0.10. All samples exhibited three strain hardening stages. The predominant fracture mode of the studied steel was ductile, with the presence of some isolated cleavage facets, the number of which increased with an increase in martensite fraction. Compared to those of hot rolled DP steels, yield strength and ultimate tensile strength are lower due to large ferrite grain size, coarse martensite area and Widmanstätten ferrite. Disciplines Engineering | Science and Technology Studies

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“…Besides, in some voids the MnS inclusions were observed for all heat treatment conditions (Fig. 16), which could be a site for void formation [6,28].…”

Section: Fractographymentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Microstructures and mechanical properties of dual phase steel produced by laboratory simulated strip casting

et al. 2015

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“…This is achieved after application of austenisation, quenching, and tempering on low alloyed steel of AISI 4340, RHA, and AR500 [24][25][26]. After the process of austenisation and quenching, crystal structure of steel is changed from austenite Face Centered Cubic structure (FCC) into carbon supersaturated Body Centered Tetragonal structure (BCT) to form martensitic or bainitic structure [27].…”

Section: Microstructuresmentioning

confidence: 99%

Mechanical properties and microstructures of steel panels for laminated composites in armoured vehicles

Jamil

Aripin

Sajuri³

et al. 2016

Int. J. Automot. Mech. Eng.

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This paper present the study about the mechanical properties of two high strength low alloy steels for replacing the current rolled homogeneous armour (RHA) for ballistic application. High strength low alloy steel has been widely adapted as a ballistic plate in light armoured vehicle. However, the current used RHA plate is very heavy thus restricted the manoeuvrability of the armoured vehicle. The aim of this study is to find materials suitable to be used for production of composite protection panel which is lighter yet has similar mechanical properties to RHA. The tensile strength and hardness of AISI 4340 and AR500 steels were evaluated and compared to that of RHA and the results were analysed based on its chemical compositions and microstructural observation. Values of these properties are primarily reflected by its microstructures and chemical compositions. Therefore, microscopic observation of microstructural arrangement and phases are essential in understanding the hardness and stress-strain behaviour of these metals. Results indicate similar tensile properties were observed in RHA and AR500 but different properties obtained for AISI 4340. Tensile strength of RHA and AR500 were 1750 MPa and 1740 MPa respectively followed by AISI 4340 at 1020 MPa. AISI 4340 steel exhibited the highest elongation at 20.6% compared to RHA and AR500 at 13.3 and 12.5%, respectively. Higher degree of carbon content in fine martensitic structure of RHA and AR500 led to high hardness. Imperfections in RHA and AR500 were also removed by hot rolling process as indicated by white banding that cause higher in tensile strength. Retained austenite and coarse microstructure of AISI 4340 steel contributed to higher ductility compared to AR500 and RHA. Therefore the tensile properties of RHA and AR500 were found similar due to its microstructure behaviour. This similarity allows AR500 to be utilised as alternatives to RHA in armour plate application.

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“…In the first case, Coldren and Tither [3] showed that a DP structure is developed during cooling after hot rolling. In the second method, the DP structure is formed after intercritical annealing of a previously rolled product [4][5][6]. Intercritical annealing leads to the formation of islands of austenite that transform to martensite or some other low-temperature transformation products, such as bainite, during rapid cooling.…”

Section: Introductionmentioning

confidence: 99%

Microstructure Modelling of Dual-Phase Steel Using SEM Micrographs and Voronoi Polycrystal Models

Katani

Ziaei-Rad

Nouri

et al. 2013

Metallogr. Microstruct. Anal.

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The microstructure of dual-phase (DP) steels is composed of a matrix of ferrite reinforced by islands of martensite and the common interphase boundaries. To study the mechanical behavior of DP steels, steel with 45% ferrite and 55% martensite was fabricated and tested in the laboratory. Two types of finite element models were then created based on SEM images. The first model directly created the grains and boundaries from the SEM images, while the second model used a Voronoi type algorithm to construct geometries which are statistically similar to the SEM images. The models consider the measured morphology of ferrite, martensite, and their phase boundaries. The Gurson damage model was then used for the ferrite and boundary regions. The obtained results correctly predicted the failure mechanisms in a DP material. The results indicate that the deformation is localized due to microstructural inhomogeneities and the nucleation of voids in the boundaries between the ferrite and martensite grains. The good correlation between the numerical and experimental observations from SEM micrographs shows the efficiency of the proposed models in predicting the failure mechanism of DP steels.

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Comparison of mechanical properties of martensite/ferrite and bainite/ferrite dual phase 4340 steels

Cited by 116 publications

References 9 publications

Microstructures and mechanical properties of dual phase steel produced by laboratory simulated strip casting

Microstructures and mechanical properties of dual phase steel produced by laboratory simulated strip casting

Mechanical properties and microstructures of steel panels for laminated composites in armoured vehicles

Microstructure Modelling of Dual-Phase Steel Using SEM Micrographs and Voronoi Polycrystal Models

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