Metallurgical investigation on failure of plain carbon steel piston rod used in hydraulic jack: Role of inclusions and surface roughness

• Published in: Engineering failure analysis Vol. 150; p. 107346
• Main Authors: Dhanya, M.S., Ranjith, R., Manwatkar, Sushant K., Kumar Gupta, Rohit, Narayana Murty, S.V.S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2023
• Subjects: Embrittlement; Failure analysis; Inclusions; Machining; Material cleanliness; Piston rod; Plain carbon steel; Surface smoothness; Material cleanliness; Failure analysis; Plain carbon steel; Piston rod; Machining; Embrittlement; Inclusions; Surface smoothness
• ISSN: 1350-6307; 1873-1961
• DOI: 10.1016/j.engfailanal.2023.107346

•Piston rod fabricated out of plain carbon steel in annealed condition used in 50 kN hydraulic jack failed during the structural qualification of ogive payload fairing of launch vehicle.•A detailed metallurgical analysis was carried out on failed piston rod using different characterization techniques like optical microscopy, scanning electron microscopy, energy dispersive spectroscopy etc.•The inclusions and impurities present in the material coupled with loading conditions and surface roughness of threads caused failure of the component. Piston rod fabricated out of plain carbon steel in annealed condition used in 50 kN hydraulic jack failed during the structural qualification of ogive payload fairing of launch vehicle. A detailed metallurgical analysis was carried out on failed piston rod using thorough characterisation and testing. Fractography observation revealed brittle cleavage features indicative of brittle failure. Extensive roughness at the thread surface was also observed. Higher content of sulphide and alumina inclusions with slightly higher content of sulphur and phosphorus beyond the acceptable limit were observed in the material. Fractography of tensile tested specimens revealed ductile failure whereas impact tested specimens showed brittle failure. The failure analysis observations have also shown brittle failure of component under dynamic loading conditions. Hence, presence of higher inclusions and impurities in the material coupled with roughness at the thread surface are the reasons for the brittle failure of piston rod.