Controlled Cooling Process and Mechanical Property of 590MPa Grade Structural Steel with Low Yield Ratio

2011 ◽  
Vol 261-263 ◽  
pp. 740-743
Author(s):  
Jian Kang ◽  
Zhao Dong Wang ◽  
Guo Yuan ◽  
Guo Dong Wang
Keyword(s):  
Volume Fraction ◽  
Charpy Impact ◽  
High Strength ◽  
Ferrite Matrix ◽  
Yield Ratio ◽  
Controlled Cooling ◽  
Final Temperature ◽  
Ultra Fast Cooling ◽  
High Rise ◽  
New Generation

To develop 590MPa grade low yield ratio steel for high-rise buildings, the new generation TMCP based on ultra fast cooling (UFC) technology was proposed. Then effects of UFC final temperature on microstructure and mechanical properties were investigated. The results show that the control of composite phases is important to obtain high strength, low yield ratio and high work hardening exponent. When UFC final temperature is 521°C, 22.5% (volume fraction) M-A phases are distributed in bainite ferrite matrix, and the excellent overall properties can be obtained, i.e., the yield strength is 570MPa, tensile strength 760MPa, yield ratio 0.75 and percentage elongation 22% with the Charpy impact energy 284J at -40°C. All these indexes can meet the requirements of relevant standards.

Control of Yield Ratio Based on Ultra Fast Cooling and Mechanical Behaviors of High Strength Aseismic Steel

2011 ◽  
Vol 228-229 ◽  
pp. 505-508 ◽  
Author(s):  
Jian Kang ◽  
Guo Yuan ◽  
Zhao Dong Wang
Keyword(s):  
Volume Fraction ◽  
Charpy Impact ◽  
High Strength ◽  
Ferrite Matrix ◽  
Constructional Steel ◽  
Yield Ratio ◽  
Second Phase ◽  
Soft Matrix ◽  
Ultra Fast Cooling ◽  
Fast Cooling

The new generation TMCP process based on ultra fast cooling has recently developed rapidly. In order to develop the low yield ratio constructional steel, the effects of cooling finishing temperature on microstructure and yield ratio of steels were studied primarily. The results show that the high strength and low yield ratio can be achieved by multiphase including M-A hard second phase and bainite ferrite soft matrix. When UFC final temperature is 521°C, the uniform M-A phases with volume fraction of 22.5% are distributed on bainite ferrite matrix, and then the yield strength is 570MPa, tensile strength 760MPa, yield ratio 0.75, and percentage elongation 22% with the Charpy impact energy 284J at -40°C. All these indexes come up to the relevant standards. The steel with lower yield ratio can be subjected to larger plastic deformation before the necking instability.

Study on the Cooling Process of Low Yield Ratio 590-780MPa Grade Steel Plates for High-Rise Buildings

2011 ◽  
Vol 194-196 ◽  
pp. 292-295 ◽  
Author(s):  
Jian Kang ◽  
Zhao Dong Wang ◽  
Guo Dong Wang
Keyword(s):  
Mechanical Properties ◽  
Structural Steel ◽  
High Strength ◽  
Ferrite Matrix ◽  
Yield Ratio ◽  
Steel Plates ◽  
Air Cooling ◽  
Soft Phase ◽  
Cooling Temperature ◽  
Ultra Fast Cooling

To develop 590/780MPa grade low yield ratio structural steel, the effects of ultra fast cooling (UFC) new process on microstructure and mechanical properties were investigated. The results showed that the low yield ratio and high strength can be obtained by proper phase compositions including relative soft phase and hard phase. For the process of UFC + air cooling, when UFC final cooling temperature was 521°C, 22.5% M-A second hard phases were distributed on bainite ferrite matrix in steel No.A2. The mechanical properties can meet requirement of 590MPa grade low yield ratio structural steel. For the process of air cooling + UFC, when UFC initial cooling temperature was 781°C, the multiphase composed of 28.3% ferrite and other bainite / martensite lath structure can ensure the high strength and low yield ratio of steel No.B1. And performance indexes can meet the requirement of 780MPa grade low yield ratio structural steel.

Transformation Induced Plasticity (TRIP) Effect Used in Forming of Carbon CMnSi Steel

2005 ◽  
Vol 500-501 ◽  
pp. 461-470 ◽  
Author(s):  
Jiří Kliber ◽  
Bohuslav Mašek ◽  
Ondrej Zacek ◽  
H. Staňková
Keyword(s):  
Continuous Casting ◽  
Hot Rolling ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Thermomechanical Processing ◽  
High Strength ◽  
Ferrite Matrix ◽  
Transformation Induced Plasticity ◽  
Trip Steels ◽  
Forming Temperature

Transformation induced plasticity (TRIP) steel combines high strength and high ductility that makes it particularly suitable for forming. Martensite within a ferrite matrix is usually obtained either by continuous casting of slabs followed by hot rolling (which is the fastest method, hence the most economical one, producing, however, relatively thick products) or by the continuous casting of slabs followed by hot rolling, cold rolling and annealing (the method used for thin products). High cooling rates, low coiling temperatures and low reduction during hot deformation were generally found to suppress the formation of polygonal ferrite and promote the presence of retained austenite. This paper focuses on development and modifications of two CMnSi-based TRIP steels with 0,23 % C;1,4 % Mn; 1,9 % Si; ( 0,08 % Nb) by means of laboratory thermomechanical processing. Description of experimental devices for the analysis of transformation plasticity under tensioncompression loading is given. Experiments were carried out on the simulator for thermaldeformation cycles SMITWELD and TANDEM was used for thermomechanical processing on the laboratory rolling mill. The maximum volume fraction of retained austenite and the resulting optimum combination of tensile strength and ductility were achieved in testing heats. Special attention was paid to volume fraction changes of single phases and to changes in morphology of phases. The results suggest that rather short isothermal bainite transformation times are sufficient to obtain TRIP microstructure. The influence of parameters of thermomechanical processing such as the amount of strain, forming temperature and austenitization time and temperature on microstructures of TRIP steels were evaluated.

New Generation TMCP Technology and its Application to 960 MPa High Strength Structural Steel Plates

2014 ◽  
Vol 922 ◽  
pp. 94-101
Author(s):  
Zhao Dong Wang ◽  
Jin Bao Zhu ◽  
Xiang Tao Deng ◽  
Bing Xing Wang ◽  
Yong Tian ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Structural Steel ◽  
New Technology ◽  
High Strength Steels ◽  
High Strength ◽  
Steel Plates ◽  
Ultra Fast Cooling ◽  
Low Temperature Impact Toughness ◽  
New Generation

The new generation thermo-mechanical controlled processing (TMCP) technology based on advanced cooling technique and equipment is introduced here in the context of 960MPa grade high strength structural steel plates. This new technology accurately controls the cooling rate and temperature, with strong influence on phase transformation and precipitation including microstructure and mechanical properties of the steel. The application of the newly developed technology applied to the production of 960MPa grade high strength structural steel demonstrated its effectiveness, especially in improving low temperature impact toughness. The yield strength was 980~1000 MPa and tensile strength 1080~1200 MPa, with impact toughness approaching 150J at-40°C.Keywords: New generation TMCP technology; Ultra fast cooling process; high strength steels; mechanical properties

Role of Delamination Fracture for Enhanced Impact Toughness in 0.05 %P Doped High Strength Steel with Ultrafine Elongated Grain Structure

2011 ◽  
Vol 409 ◽  
pp. 231-236 ◽  
Author(s):  
Meysam Jafari ◽  
Yuuji Kimura ◽  
Kaneaki Tsuzaki
Keyword(s):  
Rolling Direction ◽  
Charpy Impact ◽  
High Strength ◽  
Ferrite Matrix ◽  
Deformation Texture ◽  
Grain Structure ◽  
Shelf Energy ◽  
Temperature Range ◽  
Delamination Fracture ◽  
Fiber Deformation

Ultrafine elongated grain (UFEG) structures with strong <110>// rolling direction (RD) fiber deformation texture were produced by warm caliber-rolling at 773 K, namely tempforming in the 1200 MPa-class medium-carbon low-alloy steel with phosphorous (P) contents of 0.001 and 0.053 mass%. Charpy impact tests were performed at temperature range of-196 to 150 °C on the UFEG structure. Regardless of P content, high upper shelf energy about 145 J and a very low ductile to brittle transition temperature (DBTT) of around-175 °C were obtained. P segregation embrittlement completely disappeared in the 0.053 %P steel and both steels showed ductile fracture on the planes normal to RD at temperature range of-150 to 150 °C. The main reason for the high upper shelf energy and very low DBTT in the 0.053 %P steel would be delamination fracture along RD when both 0.001 and 0.053 %P steels showed quite similar microstructures including texture. Since the occurrence of delamination requires relatively weak interfaces or planes, P segregated to the ferrite grain boundaries and interfaces of cementite particles-ferrite matrix and made them feasible paths for crack branching and consequently delamination occurred. We showed in this work the advantage of delamination (crack arrester-type) on the high absorbed energy obtained by 0.053 %P steel in comparison with 0.001 %P steel.

Performance Characteristics of the Steels for High-Rise Buildings

2011 ◽  
Vol 415-417 ◽  
pp. 951-954
Author(s):  
Qing Bo Yu
Keyword(s):  
High Strength ◽  
Development Trend ◽  
Structural Steels ◽  
Yield Ratio ◽  
Performance Characteristics ◽  
High Rise ◽  
High Toughness ◽  
High Rise Building

With the development of high-rise buildings, the requirement to the performance of steels for high-rise buildings keeps on increasing. Besides high strength and high toughness possessed by general structural steels, the steels for high-rise buildings should possess low yield ratio, excellent welding performance, fire-resistant performance and Z-direction performance. These performance characteristics of the steels for high-rise building were introduced and its development trend was pointed out.

scholarly journals Low-Carbon Ti-Mo Microalloyed Hot Rolled Steels: Special Features of the Formation of the Structural State and Mechanical Properties

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1584
Author(s):  
Alexander Zaitsev ◽  
Nataliya Arutyunyan
Keyword(s):  
Mechanical Properties ◽  
High Strength Steels ◽  
High Strength ◽  
Ferrite Matrix ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Bulk System ◽  
Hot Rolled ◽  
New Generation ◽  
Technological Strength

Low-carbon Ti-Mo microalloyed steels represent a new generation of high strength steels for automobile sheet. Excellent indicators of difficult-to-combine technological, strength, and other service properties are achieved due to the superposition of a dispersed ferrite matrix and a bulk system of nanoscale carbide precipitates. Recently, developments are underway to optimize thermo-deformation processing for the most efficient use of phase precipitates. The review summarizes and analyzes the results of studies of mechanical properties depending on the chemical composition and parameters of hot deformation of low-carbon Ti-Mo microalloyed steels. Particular attention is paid to the features of the formation and the influence of various types of phase precipitates and the dispersion of the microstructure on mechanical properties. The advantages of Ti-Mo microalloying system and the tasks requiring further solution are shown.

500MPa Seismic Rebars Developed by Nitrogen-Rich and Vanadium-Microalloyed, Controlled Cooling Technology

2011 ◽  
Vol 189-193 ◽  
pp. 752-761 ◽  
Author(s):  
Wei Chen ◽  
Zhe Shi ◽  
Yu Zhao ◽  
Jian Chun Cao ◽  
Yu Mei Yu
Keyword(s):  
Mechanical Properties ◽  
Dislocation Line ◽  
High Strength ◽  
Ferrite Matrix ◽  
Rolling Process ◽  
Controlled Cooling ◽  
Butt Welding ◽  
Fine Grain ◽  
Transmission Electron ◽  
Cooling Technology

500MPa high-strength seismic rebars was developed by nitrogen-rich & vanadium -microalloyed, controlled cooling technology in domestic steel plant of china, microalloy precipitates, microstructure, mechanical properties, welding performance and aging properties of rebars were researched by using metallographic microscopy, scaning electron microcopy, transmission electron microscopy, x-ray diffraction apparatus, flash-butt welding and mechanical properties testing. The results show that a large number of the dispersed V (C, N) precipitates are precipitated in the grain boundary, dislocation line and the ferrite matrix, precipitation size in the ferrite matrix is 10~ 20nm, V(C,N) precipitates amount accounts for 67.54% of the total amount of vanadium in steel, effect of precipitation strengthening is remarkable; when termination temperature after controlled cooling for rebars is controlled at 710°C ～750°C , the core microstructure is polygonal ferrite and pearlite, ferrite grain grade is 11.0, outer layer microstructure is acicular ferrite, pearlite and a small amount of bainite, good effects on fine-grain strengthening and seismic performance are obtained; rebars have low strain aging and good welding performance; production cost is reduced by RMB 100 Yuan per ton steel compared with VN micro-alloyed and hot-rolling process, benefit is obvious.

scholarly journals 3D-Printed Mortars with Combined Steel and Polypropylene Fibers

Fibers ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 79
Author(s):  
Valery Lesovik ◽  
Roman Fediuk ◽  
Mugahed Amran ◽  
Arbi Alaskhanov ◽  
Aleksandr Volodchenko ◽  
...  
Keyword(s):  
Building Materials ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Polypropylene Fibers ◽  
Fine Grained ◽  
High Rise ◽  
High Adhesion ◽  
Technological Index ◽  
3D Printed ◽  
New Generation

Fibers of various origins are of great importance for the manufacture of new generation cement composites. The use of modified composite binders allows these highly efficient building materials to be used for 3D-printing of structures for various functional purposes. In this article, changes in building codes are proposed, in particular, the concept of the rheological technological index (RTI) mixtures is introduced, the hardware and method for determining which will reproduce the key features of real processes. An instrument was developed to determine a RTI value. The mixes based on composite binders and combined steel and polypropylene fibers were created. The optimally designed composition made it possible to obtain composites with a compressive strength of 93 MPa and a tensile strength of 11 MPa. At the same time, improved durability characteristics were achieved, such as water absorption of 2.5% and the F300 frost resistance grade. The obtained fine-grained fiber-reinforced concrete composite is characterized by high adhesion strength of the fiber with the cement paste. The microstructure of the developed composite, and especially the interfacial transition zone, has a denser structure compared to traditional concrete. The obtained materials, due to their high strength characteristics due to the use of a composite binder and combined fiber, can be recommended for use in high-rise construction.

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