Papers by Keyword: Alloy Element

Abstract: The global production of niobium-microalloyed steels is now a well-established industrial practice. Initially driven by experimental insights into niobium's ability to refine steel microstructures during thermomechanical processing, this technology has become especially prevalent in low-alloy steels. An important aspect of niobium's production is its natural association with tantalum, which often leads to the co-extraction of both elements. This paper investigates the impact of tantalum traces, present as a contaminant in FeNb, on the microstructure and mechanical properties of niobium-microalloyed steels. The study reveals that tantalum's presence leads to further refinement of austenitic grains without negatively affecting the alloys' yield strength. Additionally, this tantalum contamination enhances the steel samples' toughness. By exploring these subtle effects, this study provides new insights into tantalum's influence on microalloyed steels, particularly regarding microstructural refinement and mechanical performance in two specific Nb-microalloyed steel compositions.

Abstract: Mg-Al alloy is the most common application. Mg-Al alloy has the property of high specific strength and high pecific stiffness, good Vibration property, good electromagnetic shielding and anti radiation ability and so on. So Mg-Al alloy has wide application prospect in automobile, electron, elctrical equipment, transportation, avitation, national defense and military, known as the " twenty-first Century green engineering materials ".

Abstract: Effect of Cr element on microstructure of Al-3.2Mg alloys was investigated using optical microscopy, scanning electron microscopy (SEM) and EDS. Moreover, the tensile and hardness test were carried out. The results show that a minor additive of Cr can refine effectively the secondary dendrite arm spacing and decrease the number of coarse interdendritic structures. In the whole series of the alloys, the secondary dendrite arm spacing of Al–3.2Mg-0.1Cr alloy was the smallest, and the spacing presented an increasing trend with the Cr content. With high levels of Cr, the intermetallic compounds are formed by Cr with Al, Mg and Fe, the shape of the second phase particles were transformed from bulky bone shape to fine bone shape and long striped. The strength and the hardness of Al–3.2Mg alloys were greatly improved when the additions of Cr were 0.05% and 0.1%, but the ductility of the alloys remained at a low level by adding 0.05%Cr. Therefore, combining with the comprehensive properties and the microstructure, the best addition of Cr in the alloy was 0.10% in the whole series.

Abstract: In this study, effects of welding time and elements Mg, Si and Cu in aluminum alloys on hardness and tensile shear strength of aluminum alloys/steel joints in resistance spot welding have been investigated. The welding current was kept a constant 10.5kA and electrode force was 1kN. Welding time was increased from 0.067s up to 0.2s with a rise of 0.033s. Two intermetallic compound layers were generated at weld interfacial zones between aluminum alloys and steel during welding process, and the major phases were FeAl3 adjacent and directing to aluminum alloy and Fe2Al5 adjacent and directing to the steel. Diffusion of Si in aluminum alloy occurred at the interface, whereas the diffusion of Mg and Cu was not observed at the interface according to the EPMA analysis results. Hardness of intermetallic compound layers was 13.8GPa, which was about 12 times as much as that of the aluminum alloy. The largest tensile-shear strength was obtained on the condition of 0.134 and 0.167s welding time.

Abstract: In this study, usability of boron as an alloy element in gray cast iron and its effect to abrasive wear behaviour were investigated. Pin-on-drum wear tests at the room temperature carried out for seven low nickels alloyed gray cast irons with different boron addition. The mass losses, hardness values and microstructures for gray cast iron specimens with different boron alloyed were investigated for determining wear behaviour. The pin for the wear tests was manufactured from X210Cr12 cold work tool steel with material number of 1.2080. Abrasive pin-on-drum wear tests were carried out at a 165 N constant load and two different sliding speeds that are closely related to the appropriate operating conditions in rolling mills. The experimental studies have shown that wear rate decrease with increasing boron amount in chemical composition of the alloy and the wear rate at high sliding speed has decreased more rapidly than the rate at the low sliding speed with increasing boron amount.

Abstract: The goal of this research is to choose the proper method of car body welding. Properties of weld metal deposits depend on many conditions. First of all, this paper attempts to study the role of oxide inclusion sites on the transformation of austenite to acicular ferrite in steel weld metal deposits and their toughness. Safety and exploitation conditions of welded steel structure depend on many factors. The most significant of those factors are connected with materials, welding technology, state of stress and temperature. Because of that a good selection of steel and welding method is crucial to obtain proper steel structure. Car body elements of higher durability are made of low carbon and low alloy steel, very often with small amount of carbon and the amount of alloy elements such as Ni, Mn, Mo, Cr and V in low alloy steel and their welds. In the terms of the kind of steel it is used a proper welding method and adequate filler materials. In the present paper the influence of Mn, Ni, Mo, in WMD on the behaviour of steel structure for low temperature service was tested.

Abstract: Using the first-principles self-consistent discrete variational method based upon density functional theory, we investigated the energetics and the electronic structure of the 3d impurities Ni and Co in a kink on the [100](010) edge dislocation (ED) in bcc iron. The calculated results show that the interatomic energies between the impurity atom and the neighboring host atoms decrease. The bonding for the impurity atom (Ni, Co) and the neighboring host Fe atoms is weaker than that for an Fe atom at the X site and the corresponding atoms in the clean kink. These results indicate that sideways motion of the kink in the <100>{010} ED is accelerated by an impurity atom such as Ni or Co and that, consequently, the presence of impurities increases the dislocation mobility, thus leading to solid-solution softening.