Development of Seamless Pipes with Improved Strength-Toughness Combination for Hydraulic Cylinders


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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.



Materials Science Forum (Volumes 539-543)

Main Theme:

Edited by:

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

Online since:

March 2007




[1] D.O.T. § 178. 65 Spec. 39 Non reusable (non refillable) cylinders.

[2] Pressure Equipment Directive 97/23/EC.

[3] EN 10216-1/2/3/4, Seamless steel tubes for pressure purposes, European Standard.

[4] E. Anelli et al., Development of new steels with high drawability for wire-rods, European Commission, Report EUR 16781 IT (1997).

[5] P. Folgarait, E. Anelli: Wire J. Int. Vol. 37 Sept. (2004), p.62.

[6] K.W. Andrews: JISI Vol. 193 July (1965), p.721.