Thermal fatigue damage of Fecralloy co-extruded tubing
The influence of severe thermal cycling has been investigated on triplex co-extruded tube sections consisting of inner and outer Fecralloy-steel cladding on different representative substrate materials, i.e. 2(1)/4CrlMo-steel, Incoloy 800H and type 321 stainless steel. It was observed that thermal cycling can cause varying degrees of dimensional distortion depending on the substrate material and increasing in the order 2(1)/4CrlMo-steel > Incoloy 800H > type 321 SS. The observed distortions were related to the differential thermal expansion between the substrate materials and the Fecralloy steel clad and with their relative strengths. They can be explained by a simple ratchet model. The model further predicts that the magnitude of temperature cycle, the upper cycle temperature and the relative thickness of the substrate and overlayer are critical parameters in determining the overall distortion and the influence of these parameters has been substantiated experimentally. For the use of Fecralloy steel co-extruded Incoloy 800H and type 321 stainless steel at temperatures greater than 750 C, thermal cycling should be minimised. However, much longer lives would be anticipated below 750 C for all material combinations. The 2(1)/4CrlMo-steel substrate is least prone to thermal cycling damage.
Bibliographic Reference: EUR 11967 EN (1989) 81 pp.
Record Number: 198910284 / Last updated on: 1994-12-01
Original language: en
Available languages: en