A Fractographical Study on Boron Added Armor Steel Developed by Alloying and Heat Treatment to Understand Its Ballistic Performance

Abstract

Fractographical examinations present a good relationship between frac ture surface topography and basic rupture mechanism. Fracture consists of crack formation (crack nucleation) and crack growth (crack propagation). Many parametres such as type of loading, sensitivity of materials to crack play an important role on failure. Fracture in engineering alloys can occur by a transgranular (through the grains) or an intergranular (along the grain boundaries) fracture path. Scanning Electron Microscopy (SEM) is used in fractographical examinations presented in this study, due to its high resolution. In general SEM examinations are an important part of failure analysis.In this study newly developed boron added armor steel has been rolled to form sheet product. Heat treatment series including austenitization, quenching and then tempering have been applied on boron added armor steel respectively. The effects of formed microstructures on mechanical properties have been studied extensively. Furthermore failure mechanism has been determined through fractografical examinations by using SEM . Failure analysis and type of fracture provide also a good approach to understand the ballistic behaviour of armor steel. When the material is exposed to any kind of impact loading as performed by kinetic penetrator etc., it is obvious that the characteri stic of failure will give information about its ballistic performance.

The Influence of Single and Double Steel Plate Hardness on Fracture Behavior after Ballistic Impact

“…Large hole due to the projectile passed through a large plate and fracture, while small holes around the main hole showed projectile or plate fragments separated and penetrated the witness plate. Failure on the soft plate so that induced the formation of craters was a combination of process petaling and fragmentation reported in [13], which evidenced by the formation of petals and appear small fracture or soft plugging process as reported in [14] were the formation of holes with petals on the front side and then formed the main fracture driven by a projectile.…”

“…4 d)). A large impact force cannot be detained by the hard plate so that the plate of failed and perforated with a plugging mechanism reported in [13] or hard plugging in [14]. Plugging is the formation of holes due to a single fracture and sliding, while hard plugging is hole formation due to fracture that shifted that are preceded the formation of a small fracture on the side face.…”

“…The more hardness of the steel increases, then ballistic resistance increases up to a certain value will decreases and finally a failure occurs due to the process of shearing and cracked so perforated from ballistic impacts has been reported in [12]. Failure mechanism up to the perforated on the plate shapes brittle fracture, radial fracture, ductile hole growth, plugging, fragmentation and petaling has been reported [13], ductile hole formation, soft plugging, hard plugging and target shatter has been reported in [14]. Ballistic resistance of the steel is complex function from mechanical properties, such as yield strength, tensile strength, hardness, ductility and charpy.…”