Fatigue strength of austempered ductile iron-to-steel dissimilar arc-welded joints

Abstract

Nowadays, the use of different classes of materials in the same structure is increased to keep pace with innovation and high structural performances. In this context, structural components made of different materials need to be joined together and a possible solution is given by arc welding. Dissimilar welded joints must often be able to withstand fatigue loads; however, Design Standards provide fatigue strength categories only for homogeneous welded joints. The aim of the present paper is to compare the fatigue behaviour of EN-GJS-1050 austempered ductile iron-to-S355J2 steel dissimilar joints to the categories of the corresponding homogeneous steel welded joints, as suggested in International Standards and Recommendations. For this purpose, experimental fatigue tests were performed on a selection of dissimilar welded details. First, the microstructure was identified by metallographic analysis; micro-hardness measurements were collected and residual stress profiles were obtained by using the X-ray diffraction technique on a selection of joints. Misalignments were quantified for all specimens. Then, experimental fatigue tests have been performed on a number of joint geometries subject to axial or bending fatigue loadings and tested in the as-welded conditions. The fracture surfaces of the joints have been analysed to locate fatigue crack nucleation sites.

Filler materials used to weld ductile cast iron – A review

“…Ductile iron (DI) is a class of cast iron produced by treating the molten cast iron with magnesium before casting. Due to their ease to cast, about 8% lower melting energy over steel, ease of machining, wide range of mechanical properties, and economic advantages, these family of ferrous cast alloys have begun replacing cast and forged steels in some engineering applications [1][2][3][4][5][6][7][8][9][10][11]. Among cast iron materials class, the austempered ductile iron (ADI) has recently received much attention from academic and industrial research point of view [1][2][3][4][5][6][7][8][9][10][11].…”

“…Due to their ease to cast, about 8% lower melting energy over steel, ease of machining, wide range of mechanical properties, and economic advantages, these family of ferrous cast alloys have begun replacing cast and forged steels in some engineering applications [1][2][3][4][5][6][7][8][9][10][11]. Among cast iron materials class, the austempered ductile iron (ADI) has recently received much attention from academic and industrial research point of view [1][2][3][4][5][6][7][8][9][10][11]. This is owed to the fact that ADI materials possess a unique combination of properties such as fabrication simplicity, low cost, high strength-weight ratio, ductility and toughness, good fatigue strength, damping properties, moderate wear resistance, and lowest weight per unit strength ratio compared to common steels, rendering ADI an interesting industrial engineering material [1,8,10].…”

“…Among cast iron materials class, the austempered ductile iron (ADI) has recently received much attention from academic and industrial research point of view [1][2][3][4][5][6][7][8][9][10][11]. This is owed to the fact that ADI materials possess a unique combination of properties such as fabrication simplicity, low cost, high strength-weight ratio, ductility and toughness, good fatigue strength, damping properties, moderate wear resistance, and lowest weight per unit strength ratio compared to common steels, rendering ADI an interesting industrial engineering material [1,8,10]. It is this rare excellent property combination that elevates ADI materials to compete with the current industrially used lightweight alloys mostly in the automobile, rail, agriculture and mining industries to produce parts such as crankshafts, steering knuckles, brackets, valves, differential carriers, brake callipers, hubs, water pipes, etc., for use in a wide variety of applications [1,8,10].…”

“…This is owed to the fact that ADI materials possess a unique combination of properties such as fabrication simplicity, low cost, high strength-weight ratio, ductility and toughness, good fatigue strength, damping properties, moderate wear resistance, and lowest weight per unit strength ratio compared to common steels, rendering ADI an interesting industrial engineering material [1,8,10]. It is this rare excellent property combination that elevates ADI materials to compete with the current industrially used lightweight alloys mostly in the automobile, rail, agriculture and mining industries to produce parts such as crankshafts, steering knuckles, brackets, valves, differential carriers, brake callipers, hubs, water pipes, etc., for use in a wide variety of applications [1,8,10]. These properties opened new doors of application for ADI in the manufacturing industry as design engineers, vehicle makers, foundry-men and other manufacturers who are faced with the challenge to produce lighter, stronger, stiffer and cheaper metal parts [2,3].…”

The Strength and Fatigue Life analysis of Sedan Car Ramp of The Ferry Ro-Ro 5000 GT Using Finite Element Method

“…For fatigue life analysis, the procedure of the response amplitude operator was applied [11], Lotsber (2006) presents a comparison based on similar calculated hot spot stresses using the two procedures [12], In general, the presence of a size effect was agreed upon; the size effect is considered dependent on the plate thickness at the considered hot spot in addition to the size of the attachment plate and type of dynamic loading [13], One of the methods used in determining fatigue is the probabilistic method [14], Therefore, an alternative assessment method based on notch stress and very fine element meshes have been used to assess target hot spot stress values to calculate the best estimates of fatigue lives [15], Based on the review of fatigue assessment methods of welded details in steel structures [16], Meneghetti (2021) compares the fatigue behaviour of EN-GJS-1050 austempered ductile iron-to-S355J2 steel dissimilar joints to the categories of the corresponding homogeneous steel welded joints, as suggested in International Standards and Recommendations [17], Bartsch (2020) presented at longitudinal welded carried out fatigue tests in connection with numerical simulations in order to be able to evaluate the fatigue strength with better accuracy [18], In the present study, the strength and fatigue life of the internal ramp construction is investigated, the load cases are given to determine the strength and fatigue life of the ramp.…”