Papers by Keyword: Microalloying

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Authors: Chen Chen, Xiao Dong Jia, Hang Zhang, Ran Wei, Fu Shan Li
Abstract: In this paper, a centimeter-size Zr-Cu-Al-Nb bulk metallic glass (BMG) with high notch toughness of 107±13 MPa∙m0.5 was designed and fabricated by copper mold casting. With 1% Nb substitution for Zr in Zr48Cu45Al7 glass forming alloy, the glass forming ability (GFA) and toughness of the BMG were enhanced significantly. The coexistence of nano-crystallization and phase separation in the glassy matrix was observed in Zr47Cu45Al7Nb1, which would possibly lead to the high toughness of this alloy due to the easy and populous nucleation of shear bands and the increasing resistance of shear band propagation. The influences of nano-crystallization and phase separation on the toughness of BMGs are discussed in detail. The strategy utilized in this study provides a novel approach in search for new BMGs with high toughness and good GFA.
668
Authors: T.V. Shveyova, A.M. Pesin, D.O. Pustovoytov
Abstract: A tendency towards the growth of grain when heating is investigated and the stability against tempering alloyed and microalloyed steel. The advantage steel, microalloyed by vanadium and nitrogen is shown and their application for heavy-duty vehicle parts is recommended. The possibility of residual forging heat of forgings realization for their heat treatment is established.
177
Authors: P.S. Robi, Sanjib Banerjee, A. Srinivasan
Abstract: High temperature deformation behavior of Al–5.9%Cu–0.5%Mg alloy and Al–5.9%Cu–0.5%Mg alloy containing 0.06 wt.% of Sn was studied by hot compression tests at various temperatures and strain rates. Addition of trace amounts of Sn into the Al–Cu–Mg alloy system resulted in a significant increase of flow stress for all conditions of temperature and strain rate. 100% and 89% of the flow stress values during hot deformation could be predicted within ± 10% deviation values for the aluminum alloys with and without Sn content, respectively, by artificial neural network (ANN) modeling. From the deformation mechanism maps and microstructural investigation, the safe process regimes for hot working of the base alloy was identified to be at (i) very low strain rate (< 0.003 s−1) at temperature < 450 °C, and (ii) high temperature (> 400 °C) with strain rate > 0.02 s−1. For the micro-alloyed alloy, it was at low strain rates (< 0.01 s-1) for the entire temperature range studied. Flow softening for both alloys was observed to be at low strain rates and was identified to be due to dynamic recrystallization (DRX). The metallurgical instability during deformation was identified due to shear band formation and/or inter-crystalline cracking.
283
Authors: Chun Feng, Bing Zhe Bai, Yan Kang Zheng
Abstract: The effect of 0.06%Nb on the microstructure and mechanical properties of grain boundary allotriomorphic ferrite (FGBA) / granular bainite (Bg) air-cooling bainitic steels has been investigated in this paper. The results indicate that the steel acquires superior mechanical properties by adding 0.06%Nb. Compared with Non-Nb steel, the addition of 0.06%Nb increases the tensile strength and yield strength about 37.1% (From 780MPa to 1070MPa)and 26.6%(From 557MPa to 705MPa) respectively, remaining 18.3% elongation and 97J toughness. The addition of 0.06%Nb not only promotes the nucleation of intragranular ferrite but also refines the allotriomorphic ferrite grain , both of which in turn contribute to the refinement of granular bainite cluster including its ferrite platelets and M-A islands. Under the synthetic roles of the microstructure refinement and precipitation strengthening, 148MPa yield strength improvement has been acquired in the low carbon air-cooling bainitic steel by the adding of 0.06%Nb.
1191
Authors: Zhi Feng Zhang, Zhi Gang Wang, Bao Li, Jun Xu, Rui Wang
Abstract: An advanced rheo-squeeze casting process, based on the annular electromagnetic stirring (A-EMS) melt treatment technology was developed by GRINM for manufacturing near-net shape Al-alloy components with high integrity. Effects of A-EMS melt treatment process on microstructure and property of squeeze casting Al-Zn-Mg-Cu-Sc alloys were studied. The results revealed that the A-EMS melt treatment process apparently benefited grain refinement and homogeneity, and the hot-cracking of the test alloy for a complicated casting was significantly alleviated, and thus the strength and ductility of the casting were found to be comparable to those of conventionally forged alloys.
321
Authors: Zheng Ren, Jian Min Song, Xiu Rong Zhu, Gu Xin Zhou, Xin Bing Zhao, Xing Guo Zhang
Abstract: The effect of Ca, Sc and Er microalloying on the microstructure and properties of AZ61 alloys by electromagnetic casting are investigated. Experimental results show that an addition of Ca, Sc and Er refine the grains and compounds of AZ61 alloy. Mg17-xCaxAl12 phase are obtained after Ca addition. When the Ca, Sc and Er added in AZ61 alloy, some new phase contain Ca, Sc and Er are appeared. The tensile properties are improved as a result of grains and compounds refinement arter Ca, Sc and Er microalloying.
1825
Authors: Ekaterina Bocharova, Kirill Khlopkov, Roland Sebald
Abstract: Dual-phase steels are the most important AHSS grades for automotive applications. Microalloying elements such as Ti, Nb or B are widely used to improve the strength of dual-phase steels. Thus, understanding the influence of these elements on the microstructure and mechanical properties of dual-phase steels along the processing route is critical for the development of new steel grades. In this work, different microalloying elements were investigated, separately or in combination. The influences of the different elements on the microstructure and mechanical properties of dual-phase steels in the hot-rolled condition and after annealing of cold-rolled material. Dilatometer measurements were performed to investigate phase transformation during a typical continuous annealing treatment of dual-phase steel after cold rolling. It was shown that, for example, Ti has a strong influence on the mechanical properties of hot-rolled material while its influence on annealed materials after cold rolling was relatively small. Conversely, B had a strong influence on cold-rolled materials but an insignificant influence on hot-rolled materials.
483
Authors: Kodai Niitsu, Ryosuke Kainuma
Abstract: The Effect of Microalloying Elements and Compounds, such as Be, B, C, P, S, Ti, V, Cu, Zn, in, BN, VN, Mn3N, LaN, MnS and Ti4C2S2, Ranging in Amount from 0.005 to 0.2 at.%, on the α-Fe + FeLaSi Two-Phase Microstructure of a La(Fe0.89Si0.11)13 as-Melted Specimen Was Investigated. The Addition of Mn3N Was Found to Contribute to α-Fe Grain Refinement to a Certain Extent, but to Harm the Uniform Growth of the τ1 Phase in the Stage of Subsequent Annealing.
172
Authors: Zhang Ping Fei, Xin Min Huang, Rong Rong Dai
Abstract: The addition of alloy elements can improve the properties of aluminum alloy markedly. In the paper, three kinds of aluminum alloys were studied. By using SEM, EBSD and some other devices, the affects of microalloying elements on high strength and high conductivity aluminum alloy structure and properties were investigated.
643
Authors: Jyoti Prakash Dhal, Subash Chandra Mishra
Abstract: In recent years SS316LN microalloyed stainless steel is preferred for use as jacket material for Nb3Sn superconductor strands/wires. In the present investigation, microalloyed SS316LN is prepared in a vacuum induction melting furnace; Niobium and Molybdenum in their ferroalloy stage are considered as alloying element. This microalloyed steels are cast in water cooled copper mould. The tensile strength and elongation are measured and the fracture surface is studied under scanning electron microscope. It is observed that, there is a reduction of tensile strength and decrease in hardness of the steels prepared with addition of either/both the alloying elements; however there is an increase in ductility, which is helpful for cold rolling operation. From the micrographs it is observed that nitride precipitates are formed along the grain boundary, but formation of chromium carbide precipitates is reduced.
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