Development of Seamless Pipes with Improved Strength-Toughness Combination for Hydraulic Cylinders
Steel pipes for hydraulic cylinders have to offer high strength levels and good toughness. A minimum value of 27 J at – 20 °C is typically requested. In this work, a comprehensive experimental activity based on both laboratory tests and industrial trials was performed in order to investigate the benefits related to the development of multi-phase microstructures in seamless pipes for hydraulic cylinders. The effect of these microstructures on strength and toughness were analyzed. Charpy V-notch (CVN) impact tests showed that toughness increases monotonically with the increase of the intercritical temperature, i.e. when the carbon content of the newly formed austenite is reduced. Industrial trials were performed on tubes applying a proper inter-critical quenching. The product after cold drawing and stress relieving achieved high yield strength values and showed an excellent toughness, even at – 40°C, in both the transverse and longitudinal directions.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
C. Guarnaschelli et al., "Development of Seamless Pipes with Improved Strength-Toughness Combination for Hydraulic Cylinders", Materials Science Forum, Vols. 539-543, pp. 4345-4350, 2007