Influence of Cooling Rate on the Microstructures and Properties of a Nb-Ti-Mo Steel

2012 ◽  
Vol 152-154 ◽  
pp. 14-17
Author(s):  
Hai Long Yi ◽  
Yang Xu ◽  
Zhen Yu Liu ◽  
Guo Dong Wang
Keyword(s):  
Tensile Strength ◽  
Cooling Rate ◽  
High Strength ◽  
Strengthening Mechanisms ◽  
Micro Hardness ◽  
Cooling Process ◽  
Ultra Fast Cooling ◽  
Fast Cooling ◽  
Cooling Technology ◽  
Strength And Toughness

A Nb-Ti-Mo high strength steel was selected at two different cooling rates through ultra-fast cooling process, and its microstructures and strengthening mechanisms were analyzed. The results show the size of ferrite was decreased and the amount of bainite and micro-hardness were increased with increasing of cooling rate through thermal simulation. The UFC technology can improve the yield and tensile strength 25MPa and 35MPa, respectively, compared with conventional TMCP. The microstructure of this steel is mainly ferrite and good strength and toughness are caused by the refinement of ferrite and fine precipitates. Ultra-fast cooling technology improves the strength and toughness of this steel effectively.

Influence of Cooling Rate on the Microstructures and Properties of Q550

2011 ◽  
Vol 117-119 ◽  
pp. 1705-1707
Author(s):  
Fan Li ◽  
Hai Long Yi ◽  
Zhen Yu Liu ◽  
Guo Dong Wang
Keyword(s):  
High Strength ◽  
Strengthening Mechanisms ◽  
Cooling Process ◽  
Bainite Transformation ◽  
Good Strength ◽  
Ultra Fast Cooling ◽  
Fast Cooling ◽  
Cooling Technology ◽  
Conventional Cooling ◽  
Strength And Toughness

A Q550 high strength steel was selected at two different cooling rates through ultra-fast cooling process, and its microstructures and strengthening mechanisms were analyzed. The results show the bainite transformation temperature of the steel decreased with the increasing of cooling rate.The ultra-fast cooling process can improve the performance of Q550 compared with the conventional cooling process, and the yield strength, tensile strength and elongation are 600MPa, 755MPa and 19%, and - 20 °Cimpact energy is 253J, and good strength and toughness are obtained under ultra-fast cooling process. The microstructure of this steel is bainite and good strength and toughness are caused by the refinement of bainite and fine precipitates. Ultra-fast cooling technology improves the strength and toughness of this steel effectively.

Influence of Ultra-Fast Cooling Technology on Microstructure and Mechanical Properties of Ti-Microalloyed Steel

2011 ◽  
Vol 337 ◽  
pp. 414-417
Author(s):  
Hai Long Yi ◽  
Yang Xu ◽  
Zhen Yu Liu ◽  
Guo Dong Wang ◽  
Di Wu
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Microalloyed Steel ◽  
New Technology ◽  
Good Effect ◽  
Air Cooling ◽  
Cooling Process ◽  
Ultra Fast Cooling ◽  
Fast Cooling ◽  
Cooling Technology

In recent years, the ultra-fast cooling process is a new technology used to control the strip cooling process in the international which corresponds to an average cooling rate higher than 150°C/s. This new technology can provide an effective means to the development of low-cost and high-performance steels. In this paper, the phase transformation temperatures, microstructures and mechanical properties of a Ti microalloyed steel were investigated by means of a themomechanical simulator and a D450mm mill equipped with ultra-fast cooling device. The results show that the phase transition temperatures decreased and micro-hardness increased with the increasing of cooling rate. The microstructures of steel used ultra-fast cooling process was small and more uniform than the ones used laminar flow cooling and air cooling process, and finer and uniformity dispersed precipitates can be produced under ultra-fast cooling process, hence higher yield strength and good elongation was obtained for the steel. The ultra-fast cooling technology has a good effect on the microstructures and properties of the Ti microalloyed steel.

Study on CCT Curve and Microstructure Evolution of HRB500E

2013 ◽  
Vol 470 ◽  
pp. 699-702
Author(s):  
Peng Tian ◽  
Zhi Yong Zhong ◽  
Rui Guo Bai ◽  
Xing Li Zhang ◽  
Quan Li Wang ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Microstructure Evolution ◽  
Theoretical Basis ◽  
High Strength ◽  
Micro Hardness ◽  
Cooling Process ◽  
Controlled Cooling ◽  
Steel Rebar ◽  
Cct Curve ◽  
Hardness Change

The microstructure evolution and hardness change were studied for vanadium containing high strength seismic rebar HRB500E at different cooling rates. The experimental results showed that bainite and martensite gradual emerged with the increasing cooling rate and resulted in an increasing micro-hardness. The cooling rate should be controlled at 0.5°C/s to 7°C/s to ensure good performances of steel rebar. The CCT curve of HRB500E measured with the inflation method and metallographic-Hardness method could provide the theoretical basis for controlled cooling process.

High Strength Sinter-Hardening Powder Metallurgy Alloys

2008 ◽  
Vol 51 ◽  
pp. 3-9 ◽  
Author(s):  
K.S. Hwang ◽  
M.W. Wu ◽  
Chia Cheng Tsai
Keyword(s):  
Tensile Strength ◽  
Powder Metallurgy ◽  
Cooling Rate ◽  
High Hardness ◽  
High Strength ◽  
Alloying Elements ◽  
Cooling Rates ◽  
The Matrix ◽  
Fast Cooling ◽  
The Cost

High strength and high hardness can be readily attained after sintering when sinter-hardening grade powder metallurgy alloys are used. However, fast cooling rates greater than 60°C/min are usually required. This increases the cost of the sintering equipment and maintenance. To lower the required minimum cooling rate, the homogeneity of the alloying elements in the matrix and the hardenability of the material must be improved. Among the various popular alloying elements, nickel and carbon are the two most non-uniformly distributed elements due to their repelling effect. It is found that to improve their homogenization, the addition of Cr and Mo can alleviate the repelling effect between Ni and C. As a result, weak Ni-rich/C-lean ferrite and austenite are eliminated and replaced by hard bainite and martensite. A tensile strength of 1323 MPa and a hardness of 39 HRC are attained in sinter-hardened Fe-3Cr-0.5Mo-4Ni-0.5C compacts without any quenching treatment.

scholarly journals Development and Application of Thermo-mechanical Control Process Involving Ultra-fast Cooling Technology in China

2019 ◽  
Vol 59 (12) ◽  
pp. 2131-2141
Author(s):  
Zhaodong Wang ◽  
Bingxing Wang ◽  
Bin Wang ◽  
Yong Tian ◽  
Tian Zhang ◽  
...  
Keyword(s):  
Control Process ◽  
Mechanical Control ◽  
Ultra Fast Cooling ◽  
Fast Cooling ◽  
Cooling Technology

scholarly journals Enhancing the Mechanical Properties of a Hot Rolled High-Strength Steel Produced by Ultra-Fast Cooling and Q&P Process

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 958 ◽  
Author(s):  
Teng Wu ◽  
Run Wu ◽  
Bin Liu ◽  
Wen Liang ◽  
Deqing Ke
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Controlled Rolling ◽  
Grain Structure ◽  
Ultra Fast Cooling ◽  
Advanced High Strength Steels ◽  
Fast Cooling ◽  
Austenite Grains ◽  
Hot Rolled

The quenching and partitioning (Q&P) process of advanced high strength steels results in a significant enhancement in their strength and ductility. The development of controlled rolling and cooling technology provides an efficient tool for microstructural design in steels. This approach allows to control phase transformations in order to generate the desired microstructure in steel and, thus, to achieve the required properties. To refine grain structure in a Fe-Si-Mn-Nb steel and to generate the microstructure consisting of martensitic matrix with embedded retained austenite grains, hot rolling and pressing combined with ultrafast cooling and Q&P process is employed. The slender martensite in hot rolled Q&P steel improves the strength of test steel and the flake retained austenite improves the plasticity and work hardening ability through the Transformation Induced Plasticity (TRIP) effect.

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