Journal of Constructional Steel Research 54 (2000) 161–172 www.elsevier.com/locate/jcsr Nominal stress range fatigue of stainless steel ﬁllet welds — the effect of weld size Kari E. Lahti a,* , Hannu Ha ¨nninen b , Erkki Niemi c a Oy Esab, Helsinki, Finland b Helsinki University of Technology, Helsinki, Finland c Lappeenranta University of Technology, Lappeenranta, Finland Abstract Three-point bending nominal stress range fatigue of stainless steel ﬁllet welds was tested using two stainless steel grades: ferritic–martensitic EN 1.4003 and austenitic EN 1.4310. The test results obtained were shown to be in good agreement with suggested fatigue classes in the Eurocode 3 design standard, derived from fatigue data on structural steels. However, if the size of the weld was increased, and the failure location could be moved to the weld toe instead of the weld root, a signiﬁcant increase in fatigue strength was observed. Eurocode 3 was found to describe well the fatigue characteristics of the ‘worst-case’ welds, i.e., welds prone to root failure.  2000 Elsevier Science Ltd. All rights reserved. Keywords: Nominal stress; Fatigue; Stainless steel; Weld size; Throat thickness ; EN 1.4002; EN 1.4310 1. Introduction The fatigue strength of a material, as well as that of weldments, are key factors that are studied when selecting materials for applications which are prone to fatigue. The design of a structure under ﬂuctuating loading needs careful consideration of applicable design guidelines and categorization of joint types of every detail of the structure. For example, in order to produce a fatigue-resistant transportation vehicle, the use of a suitable design standard such as Eurocode 3 (1992) [1] is needed. However, in the case of stainless steels, there is no speciﬁc design code dealing with fatigue at the moment. It has been customary to apply the same design guide- * Corresponding author. Tel.: + 358-9547-7853; fax: + 358-9547-7773. E-mail address: kari.lahti@esab.ﬁ (K.E. Lahti). 0143-974X/00/$ - see front matter  2000 Elsevier Science Ltd. All rights reserved. PII:S0143-974X(99)00056-5