Failure Analysis of AISI 440C Steel Ball Screws Used in the Actuator System of a Satellite Launch Vehicle
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In view of its excellent wear and corrosion resistance, AISI 440C steel is the material of choice for the fabrication of ball screws used in actuator systems of satellite launch vehicles. During the routine acceptance test of a ball screw, longitudinal cracks were observed at the shaft location of the ball screw. The optical microstructure of the ball screw material (AISI 440C) revealed the presence of aligned carbides (carbide banding). Fractographic observations revealed the cracking to be along the carbide bands. Based on detailed optical and scanning electron microscopic observations, the cracking of the ball screws was attributed to the carbide bands.
KeywordsAerospace fasteners Brittle fracture Characterization Cracking behavior
The authors wish to place on record their deep sense of gratitude to the Group Director, Materials and Metallurgy Group, and the Deputy Director, Materials and Mechanical Entity, for their encouragement and support during the course of this work. They wish to thank the Director, VSSC, for his kind permission to publish this work.
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