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Because of the promising corrosion resistance and load-bearing capacity, titanium-clad (TC) bimetallic steel has gained increasing attention in ocean/coastal civil and structural engineering. Due to the double-layer nature of TC bimetallic steel, the characteristics of the structural member's geometry and weld details are considerably different from that of conventional steel members. Even though previous studies have conducted systematical clarifications on parent material of TC bimetallic steels, the mechanical behaviors of weld joints are still vague. This paper firstly describes the manufacture features of TC bimetallic steel welded joints and welded members. Subsequently, the type II and type III butt-welded joints provided by GB/T 13149-2009 are selected to study the corresponding tensile mechanical behavior. Two butt-welded TC bimetallic steel plates were fabricated from hot-rolled bonding TA2 + Q355B TC bimetallic steel and welding wire of ER55-Ni1 and ERTA2ELI. Eight tensile coupons were then extracted from the two welded plates and loaded to failure monotonically. The failure mechanism, stress–strain curves and key mechanical properties are studied and compared with that of parent material. It is found that both types of welded joints possess two fracture points. The first one refers to the fracture of weld joint between the clad layer and titanium cover plate, whilst the second one is the eventual fracture of substrate metal. When the first fracture point is reached, the stress–strain relation exhibits a sharp drop in stress value. Thereafter, a strain-hardening behavior can still be observed prior to the ultimate strength point. The first fracture-induced stress drop of type II joint is less than that of type III joint, whilst the strain-hardening amount of type II joint is more outstanding than that of type III joint. The fracture elongations of type II joint and type III joint are respectively 37% and 57% that of the parent material, whilst the proportions between the ultimate strengths of welded joints and parent material are, respectively, 90% and 93%. In general, the two types of TC bimetallic steel weld joints investigated herein exhibit favorable load-bearing capacity but unfavorable ductility and deformability. Based upon the experimental results, the structural design methodology of welded TC bimetallic steel structure is discussed. The investigations conducted in this paper can provide reference for development of structural design theory of welded TC bimetallic steel structure. [ABSTRACT FROM AUTHOR]

Titanium-clad (TC) bimetallic steel is an advanced composite steel consisting of metallurgically bonded titanium alloy and structural steel. This paper compared the high-cycle fatigue properties of three types of TC bimetallic steels, including two hot-rolled bonding types with different bonding strengths and an explosion-bonded type. The three types of TC bimetallic steels were all manufactured from TA2 titanium alloy as the cladding metal and Q355B structural steel as the substrate metal, of which the thicknesses are 2 mm and 8 mm, respectively. Based on the comparison results, the qualitative relationship between the bonding interface strength and the manufacturing methods with the basic mechanical and high-cycle fatigue properties was obtained. It was found that the different manufacturing methods and the bonding degree of the two component metals resulted in the different nonlinear yield plateau in the TC bimetallic steel. The high bonding strength seems to affect the failure mode of the tensile coupons. The bonding interface shear strength only slightly affects the tensile performance, which exhibits visible effects only when the test strain reaches the fractured state. In addition, three failure modes in total were found in the high-cycle fatigue tests for the three types of TC bimetallic steel. The manufacturing methods and the bonding interface strength significantly affect the fatigue phenomena of the TC bimetallic steel. The hot-rolled bonding TC bimetallic steel with high bonding strength has a 10% improvement in fatigue performance than the one with low bonding strength. Despite this, the manufacturing methods significantly affect the fatigue ratio, while the influence of the bonding strength on the high cycle fatigue performance is limited. The research outcomes can provide reference for the selection of different manufacturing methods and interfacial conditions for the use of TC bimetallic steel in structural engineering. [ABSTRACT FROM AUTHOR]

A new S600E sorbite stainless steel (SS), which performs outstanding mechanical properties, was introduced in a plate girder to enhance the resistant performance and durability. The resistance from the flange for S600E sorbite SS plate girders developing post-buckling capacity was investigated through numerical analyses, which included the material and geometrical nonlinearity. The value of distance between plastic hinges performed significant effects on resistance from flange. There was a certain distribution range of the flange plastic hinge. Hence, it was difficult to determine the value of distance between plastic hinges accurately based merely on the failure behavior. Considering the theoretical basis of EN 1993-1-4: 2006+A1, the new methods to obtain resistance from the flange and determine the value of distance between the plastic hinges were proposed to avoid the aforementioned error. The parametric study was conducted to investigate the effect of key parameters on the resistance from the flange. To take the above effect into account, a correction factor was proposed for the design equation in EN 1993-1-4: 2006+A1 to predict the distance between flange plastic hinges accurately. The comparison was conducted to validate the accuracy of the proposed equations. The results indicated that the new modified equation could be used to predict the resistance from the flange of the S600E sorbite SS plate girder more accurately. [ABSTRACT FROM AUTHOR]