Improved Rolled Homogeneous Armor (IRHA) Steel Through Higher Hardness.

Prifti, Joseph J.; Castro, Michael; Squillacioti, Richard; Cellitti, R. A.

doi:10.21236/ada329222

Cited by 6 publications

(7 citation statements)

References 1 publication

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“…Similar to spectrometer result, carbon content in AR500 was higher than RHA. Consequently, higher hardness could be achieved, as reported by [24]. Besides interstitial carbon that resists slippage, grain boundary also acts as a pinning point to resist dislocations.…”

Section: Hardness Test Resultsmentioning

confidence: 76%

“…There are several factors that contribute to hardness increment primarily its microstructure phase. Hardenability was adequate to achieve by high percentage of martensite [24]. As seen in Figure 5(b) and 5(c), RHA and AR 500 consist of fully martensitic phase.…”

Section: Hardness Test Resultsmentioning

confidence: 91%

“…The materials used in this study were three types of high strength low alloy steel suitable for ballistic application namely rolled homogenous armour (RHA) steel, ABREX abrasion-resistant steel (AR500), and AISI 4340 steel plate [23][24][25]. RHA is most commonly utilised on high strength steel in armoured vehicles due to its high tensile strength and toughness.…”

Section: Materials Selectionmentioning

confidence: 99%

“…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%

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

Jamil

Aripin

Sajuri³

et al. 2022

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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Section: Hardness Test Resultsmentioning

confidence: 76%

Section: Hardness Test Resultsmentioning

confidence: 91%

Section: Materials Selectionmentioning

confidence: 99%

Section: Microstructuresmentioning

confidence: 99%

See 2 more Smart Citations

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

Jamil

Aripin

Sajuri³

et al. 2022

Int. J. Automot. Mech. Eng.

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show abstract

“…Numerous grades of armour steel are defined in defence standards [1-3] with mechanical performance and metallurgy optimised for protection against specific threats whilst maintaining adequate engineering properties. Class 4a rolled homogenous armour [1], generally referred to as improved rolled homogenous armour (IRHA) [4] is a modern grade of armour steel optimised for combined strength and toughness with a Brinell hardness between 420 and 470. High hardness armour (HHA) steel [2] is optimised for ballistic protection with a Brinell hardness between 477 and 534 and lower Charpy fracture toughness requirements than the IRHA.…”

Section: Introductionmentioning

confidence: 99%

High strain rate and high temperature response of two armour steels: Experimental testing and constitutive modelling

et al. 2018

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Under ballistic impact or blast loading, the high strain rate and high temperature behaviour of armour steels is key to their response to a given threat. This experimental and numerical investigation examines the tensile response of a class 4a improved rolled homogenous armour steel (IRHA) and a high hardness armour steel (HHA). Cylindrical tensile specimens were tested at a range of strain rates from 0.001 s-1 to 2700 s-1. Quasi-static, elevated temperature tests were performed from room temperature up to 300° C. While the HHA is strain rate insensitive, the IRHA displays a significant increase in strength across the range of loading rates reducing the ultimate strength difference between the materials from 19% at 0.001s-1 to 4.6% at 2700s-1. An inverse numerical modelling approach for constitutive model calibration is presented, which accurately captured the dynamic material behaviour. The modified Johnson-Cook strength and Cockcroft-Latham (C-L) fracture models were capable of predicting the ballistic limit of each material to within 5% of the experimental result and to within 10% for deformation under blast loading. The blast rupture threshold of both materials was significantly over-estimated by the C-L model suggesting stress state or strain rate effects may be reducing the ductility of armour steel under localised blast loading.

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