Development of Micro-Alloying Ultra-Fine Grain High Strength Steel Produced by EAF-TSCR

2011 ◽  
Vol 697-698 ◽  
pp. 474-478
Author(s):  
Ji Xiang Gao ◽  
Xin Ping Mao ◽  
L.J. Li
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Continuous Casting ◽  
High Strength Steel ◽  
Raw Materials ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Fine Grain ◽  
Ferrite Grain Size

Based on the characteristics of raw materials in EAF-TSCR, the composition of VN micro-alloyed was designed, the processes of the steelmaking, continuous casting, soaking, rolling, cooling were controlled, and at last the VN Micro-alloying high strength steel with ultra-fine grain was developed. The ferrite grain size of the steel reaches 3.0 to 4.0 microns, and the yield strength of which reaches 550MPa. Besides, the steel processes good toughness, cold formability and weldability. In the end, the strengthening mechanism of the ultra-fine steel was discussed.

Microstructure and Property of 700MPa Ti Microalloyed High Strength Steel Produced by EAF-CSP

2011 ◽  
Vol 287-290 ◽  
pp. 961-965
Author(s):  
Ji Xiang Gao ◽  
Xin Ping Mao ◽  
Qi Lin Chen ◽  
Lie Jun Li
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Continuous Casting ◽  
High Strength Steel ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Rolling Process ◽  
Precipitation Strengthening ◽  
Smelting Process ◽  
Hot Rolled

High strength steel ZJ700MC with yield strength grade of 700 MPa was successfully developed by Ti micro-alloyed technology in the EAF-CSP line at Zhujiang Steel. The composition design, smelting process, continuous casting and rolling process of the steel, as well as the mechanical properties of the hot-rolled product are introduced in the paper. An analysis on the strengthening mechanism of the high strength steel shows that the enhanced strength and toughness of the steel were caused by the refinement of ferrite grain and the precipitation strengthening of TiC.

scholarly journals Microstructure and Enhanced Properties of Copper-Vanadium Nanocomposites Obtained by Powder Metallurgy

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 339 ◽  
Author(s):  
Yong Wang ◽  
Jinguo Wang ◽  
Haohao Zou ◽  
Yutong Wang ◽  
Xu Ran
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Yield Strength ◽  
Grain Boundary ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Copper Matrix ◽  
Dispersion Strengthening ◽  
Annealed Copper ◽  
Grain Boundary Strengthening

Cu-2.4 wt.%V nanocomposite has been prepared by mechanical alloy and vacuum hot-pressed sintering technology. The composites were sintered at 800 °C, 850 °C, 900 °C, and 950 °C respectively. The microstructure and properties of composites were investigated. The results show that the Cu-2.4 wt.%V composite presents high strength and high electrical conductivity. The composite sintered at 900 °C has a microhardness of 205 HV, a yield strength of 404.41 MPa, and an electrical conductivity of 79.5% International Annealed Copper Standard (IACS); the microhardness and yield strength reduce gradually with the increasing consolidation temperature, which is mainly due to the growth of copper grain size. After sintering, copper grain size and V nanoparticle both maintain in nanoscale; the strengthening mechanism is related to grain boundary strengthening and dispersion strengthening, while the grain boundary strengthening mechanism plays the most important role. This study indicates that the addition of small amounts of V element could enhance the copper matrix markedly with the little sacrifice of electrical conductivity.

scholarly journals Effect of Heat Treatment on Mechanical Properties and Microstructure Morphology of Low-Alloy High-Strength Steel

2016 ◽  
Vol 61 (2) ◽  
pp. 475-480
Author(s):  
K. Bolanowski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
High Strength Steel ◽  
High Strength ◽  
Strengthening Phase ◽  
Average Grain Size

Abstract The paper analyzes the influence of different heat treatment processes on the mechanical properties of low-alloy high-strength steel denoted by Polish Standard (PN) as 10MnVNb6. One of the findings is that, after aging, the mechanical properties of rolled steel are high: the yield strength may reach > 600 MPa, and the ultimate tensile strength is > 700 MPa. These properties are largely dependent on the grain size and dispersion of the strengthening phase in the ferrite matrix. Aging applied after hot rolling contributes to a considerable rise in the yield strength and ultimate tensile strength. The process of normalization causes a decrease in the average grain size and coalescence (reduction of dispersion) of the strengthening phase. When 10MnVNb6 steel was aged after normalization, there was not a complete recovery in its strength properties.

Microstructure and Properties of Ultrafast Annealed High Strength Steel

2013 ◽  
Vol 753 ◽  
pp. 554-558 ◽  
Author(s):  
Roumen H. Petrov ◽  
Farideh Hajyakbari ◽  
Fernando Ramos Saz ◽  
Jurij Sidor ◽  
Maria Jesus Santofimia ◽  
...  
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
High Strength Steel ◽  
High Strength ◽  
Deformation Texture ◽  
Point Of View ◽  
Structural Refinement ◽  
Cold Rolled ◽  
Ferrite Grain Size ◽  
Martensite Structure

The grain size, recrystallization, phase transformation and mechanical properties of a cold-rolled high-strength steel (HSS) are studied after annealing with high (~140°C/s) and ultra-high (~1500°C/s) reheating rate, followed by subsequent water quenching without isothermal soaking. By monitoring the hardness and microstructure, it was shown that the increase of the reheating rate from 140°C/s to 1500°C/s causes grain refinement from 5 µm to 1 µm in diameter and the final ferrite grain size depends significantly on the reheating temperature and reheating rate. It was observed that after an extreme reheating rate of ~1500°C/s the α-γ phase transformation starts before the completion of recrystallization in the recovered matrix. The crystallographic texture of the ultrafast reheated and water-quenched high-strength steel inherits the cold-rolled deformation texture with well pronounced RD and ND texture fibres, even after the α-γ-α′ phase transformations. It was found that the ultrafast reheating results in a very fine non-equilibrium ferrite-martensite structure with an excellent ultimate tensile strength of ~1400 MPa and an acceptable elongation at fracture. The observed data are very promising from industrial application point of view and open up possibilities for further structural refinement and alternative texture control.

Correlation Between Microstructure and Yield Strength in Low-Carbon High-Strength Microalloyed Steels

2006 ◽  
Author(s):  
K. Poorhaydari ◽  
B. M. Patchett ◽  
D. G. Ivey
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
High Strength ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Microscopy Imaging ◽  
Relative Contribution ◽  
Fine Grain ◽  
Structural Applications ◽  
Carbon Microalloyed

Microalloyed pipeline and structural steels are currently graded according to their yield strength. In this work, different microstructural factors that affect the yield strength of the steels are assessed and their contributions to the strength are estimated for several low-carbon microalloyed steels, used in pipeline or structural applications. Emphasis is placed on the relative contribution of grain/sub-grain size, precipitate distribution and dislocation density. Accurate grain/sub-grain size measurements were only possible through electron microscopy imaging. It was found that the increased strength is mainly due to the formation of bainitic structures with fine grain/sub-grain sizes. The contribution from other strengthening sources such as precipitates, dislocations and atoms in solid solution is limited and does not vary much among the several grades examined here. The variation in hardness among the fine-grained heat-affected zone samples (heat input range 0.5–2.5 kJ/mm) of one of the steels was also explained based on the microstructural changes.

scholarly journals Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1988
Author(s):  
Tibor Kvackaj ◽  
Jana Bidulská ◽  
Róbert Bidulský
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
High Strength Steel ◽  
Single Phase ◽  
Hsla Steel ◽  
High Strength ◽  
Strength Properties ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Steel Grades

This review paper concerns the development of the chemical compositions and controlled processes of rolling and cooling steels to increase their mechanical properties and reduce weight and production costs. The paper analyzes the basic differences among high-strength steel (HSS), advanced high-strength steel (AHSS) and ultra-high-strength steel (UHSS) depending on differences in their final microstructural components, chemical composition, alloying elements and strengthening contributions to determine strength and mechanical properties. HSS is characterized by a final single-phase structure with reduced perlite content, while AHSS has a final structure of two-phase to multiphase. UHSS is characterized by a single-phase or multiphase structure. The yield strength of the steels have the following value intervals: HSS, 180–550 MPa; AHSS, 260–900 MPa; UHSS, 600–960 MPa. In addition to strength properties, the ductility of these steel grades is also an important parameter. AHSS steel has the best ductility, followed by HSS and UHSS. Within the HSS steel group, high-strength low-alloy (HSLA) steel represents a special subgroup characterized by the use of microalloying elements for special strength and plastic properties. An important parameter determining the strength properties of these steels is the grain-size diameter of the final structure, which depends on the processing conditions of the previous austenitic structure. The influence of reheating temperatures (TReh) and the holding time at the reheating temperature (tReh) of C–Mn–Nb–V HSLA steel was investigated in detail. Mathematical equations describing changes in the diameter of austenite grain size (dγ), depending on reheating temperature and holding time, were derived by the authors. The coordinates of the point where normal grain growth turned abnormal was determined. These coordinates for testing steel are the reheating conditions TReh = 1060 °C, tReh = 1800 s at the diameter of austenite grain size dγ = 100 μm.

Design of a novel HSLA steel with a combination of high strength (140–160 ksi) and excellent toughness

2021 ◽  
Vol 112 (10) ◽  
pp. 800-811
Author(s):  
Mehdi Soltan Ali Nezhad ◽  
Sadegh Ghazvinian ◽  
Mahmoud Amirsalehi ◽  
Amir Momeni
Keyword(s):  
Impact Toughness ◽  
Yield Strength ◽  
Hsla Steel ◽  
Charpy Impact ◽  
High Strength ◽  
Controlled Rolling ◽  
The Other ◽  
Grain Structure ◽  
Charpy Impact Toughness ◽  
Fine Grain

Abstract Three steels were designed based on HSLA-100 with additional levels of Mn, Ni, Cr and Cu. The steels were prepared by controlled rolling and tempered at temperatures in range of 550–700°C. The continuous cooling time curves were shifted to longer times and lower temperatures with the increased tendency for the formation of martensite at lower cooling rates. The microstructures revealed that controlled rolling results in austenite with uniform fine grain structure. The steel with the highest amount of Mn showed the greatest strength after tempering at 750 °C. The top strength was attributed to the formation of Cu-rich particles. The steel with 1.03 wt.% Mn, tempered at 650 °C exhibited the best Charpy impact toughness at –85°C. On the other hand, the steel that contained 2.11 wt.% Mn and tempered at 700 °C showed the highest yield strength of 1 097.5 MPa (∼159 ksi) and an impact toughness of 41.6 J at –85°C.

High-Strength Steel Hot Forming Mechanics Performance and Characteristic Experimental Study

2016 ◽  
Vol 693 ◽  
pp. 800-806
Author(s):  
You Dan Guo
Keyword(s):  
Yield Strength ◽  
High Strength Steel ◽  
High Strength ◽  
High Energy ◽  
Absorption Capacity ◽  
Hot Forming ◽  
Gas Content ◽  
Strength Increase ◽  
Gradual Change ◽  
Forming Process

In high-strength steel hot forming, under the heating and quenching interaction, the material is oxidized and de-carbonized in the surface layer, forming a gradual change microstructure composed of ferrite, ferrite and martensite mixture and full martensite layers from surface to interior. The experiment enunciation: Form the table to ferrite, ferrite and martensite hybrid organization, completely martensite gradual change microstructure,and make the strength and rigidity of material one by one in order lower from inside to surface, ductility one by one in order increment in 22MnB5 for hot forming;Changes depends on the hot forming process temperature and the control of reheating furnace gas content protection, when oxygen levels of 5% protective gas, can better prevent oxidation and decarburization;Boron segregation in the grain boundary, solid solution strengthening, is a major cause of strength increase in ;The gradual change microstructure in outer big elongation properties, make the structure of the peak force is relatively flat, to reduce the peak impact force of structure, keep the structure of high energy absorption capacity;With lower temperature, the material yield strength rise rapidly,when the temperature is 650 °C, the yield strength at 950 °C was more than 3 times as much.

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