The Influence of Continuous Cooling Rate on Nano-Precipitation Behavior of a Ti-Bearing Steel undergone Hot Deformation

2017 ◽  
Vol 89 (3) ◽  
pp. 1700361
Author(s):  
Fengqin Ji ◽  
Chengning Li ◽  
Wenwen Song ◽  
Guodong Wang
Keyword(s):  
Cooling Rate ◽  
Hot Deformation ◽  
Bearing Steel ◽  
Precipitation Behavior ◽  
Continuous Cooling

scholarly journals Copper Precipitation Behavior during Continuous Cooling and Subsequent Aging of Powder-Forged Fe-2.5Cu-C Alloy

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1350
Author(s):  
Sui Wang ◽  
Yake Wu ◽  
Tengyu Zhang ◽  
Feng Jiang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
High Performance ◽  
Theoretical Calculations ◽  
Combined Effects ◽  
Precipitation Behavior ◽  
Subsequent Aging ◽  
Continuous Cooling ◽  
Copper Precipitation ◽  
Secondary Precipitates

Microstructure and property evolution of a powder-forged Fe-2.5Cu-C alloy during continuous cooling and subsequent aging were investigated to improve its mechanical properties. During continuous cooling, copper precipitates formed were consistent with the interphase mechanism when the cooling rate was less than 7 °C/s; however, the hardness of the specimen was always higher at faster cooling rates because finer grains and harder phases formed. During subsequent aging, copper precipitates formed and/or coarsened continuously while the hardness of the alloys was greatly influenced by the combined effects of the primary and secondary precipitates, as revealed by the theoretical calculations. In addition, the forming and evolving mechanisms of the copper precipitates at different stages were also discussed based on the experimental results. This study will provide guidance to the industry for achieving high performance in the powder-forged products by treatment manipulation.

Influence of Chromium Content and Prior Deformation on the Continuous Cooling Transformation Diagram of Low-Carbon Bainitic Steels

2020 ◽  
Vol 835 ◽  
pp. 58-67
Author(s):  
Mohammed Ali ◽  
Antti J. Kaijalainen ◽  
Jaakko Hannula ◽  
David Porter ◽  
Jukka I. Kömi
Keyword(s):  
Cooling Rate ◽  
Hot Deformation ◽  
Laser Scanning ◽  
Chromium Content ◽  
Bainitic Ferrite ◽  
Granular Bainite ◽  
Low Carbon ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling

The effect of chromium content and prior hot deformation of the austenite on the continuous cooling transformation (CCT) diagram of a newly developed low-carbon bainitic steel has been studied using dilatometer measurements conducted on a Gleeble 3800 simulator with cooling rates ranging from 2-80 °C/s. After austenitization at 1100 °C, specimens were either cooled without strain or given 0.6 strain at 880 °C prior to dilatometer measurements. The resultant microstructures have been studied using laser scanning confocal microscopy, scanning electron microscopy and macrohardness measurements. CCT and deformation continuous cooling transformation (DCCT) diagrams were constructed based on the dilatation curves, final microstructures and hardness values. Depending on the cooling rate, the microstructures of the investigated steels after cooling from the austenite region consist of one or more of the following microstructural components: lath-like upper bainite, i.e. bainitic ferrite (BF), granular bainite (GB), polygonal ferrite (PF) and pearlite (P). The proportion of BF to GB as well as the hardness of the transformation products decreased with decreasing cooling rate. The cooling rate at which PF starts to appear depends on the steel composition. With both undeformed and deformed austenite, increasing the chromium content led to higher hardenability and refinement of the microstructure, promoting the formation of BF and shifting the ferrite start curve to lower cooling rates. Prior hot deformation shifted the transformation curves to shorter times and higher temperatures and led to a reduction in hardness at the low cooling rates through the promotion of ferrite formation.

Continuous Cooling Transformation Behavior of X70 Pipeline Steel

2013 ◽  
Vol 690-693 ◽  
pp. 2205-2209
Author(s):  
Hong Mei Yang
Keyword(s):  
Cooling Rate ◽  
Hot Deformation ◽  
Acicular Ferrite ◽  
Transformation Temperature ◽  
Pipeline Steel ◽  
Continuous Cooling Transformation ◽  
X70 Pipeline Steel ◽  
Continuous Cooling ◽  
Transformation Curve ◽  
Continuous Cooling Transformation Curve

The continuous cooling transformation behaviors were researched on X70 pipeline steel through two pass deformation and non-deformed austenite using Gleeble-3500 thermal mechanical simulator, and static continuous cooling transformation curve and dynamic continuous cooling transformation curve were measured through thermal dilation method and metallographic method. The influence of cooling rate and deformation parameters on microstructure was analyzed. The results show that the hot deformation accelerates the acicular ferrite and polygonal ferrite phase transformation, increases the starting transformation temperature and the finishing transformation temperature significantly, and shifts the CCT curve moving upward to the left side corner. Acicular ferrite is obtained in practice using accelerated cooling rate after deformation Acicular ferrite can be obtained in wider range of cooling rates, and microstructure and island structure is finer through hot deformation.

Dynamic CCT Curve of Hot Deformation Austenite in 55SiCr Steel

2012 ◽  
Vol 548 ◽  
pp. 225-228
Author(s):  
Yong Jun Zhang ◽  
Chuan Da Cui ◽  
Jing Tao Han
Keyword(s):  
Cooling Rate ◽  
Hot Deformation ◽  
Transformation Products ◽  
Thermal Simulation ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Microstructure Transformation ◽  
Cct Curve ◽  
Rate Form ◽  
Transformation Curve

The CCT (Continuous Cooling Transformation) curve of hot deformation austenite in 55SiCr steel was measured on Gleeble-1500 thermal simulation machine, the microstructure and hardness of transformation products under different cooling velocities were observed. The microstructure transformation regularity with being cooled continuously were emphatically researched at the cooling rate form 0.1°C/s to 15 °C/s. The results can provide a instruction for producing 55SiCr steel.

Precipitation Behavior of Steels with Various Copper during Continuous Cooling

2010 ◽  
Vol 638-642 ◽  
pp. 3573-3578 ◽  
Author(s):  
Xue Min Wang ◽  
Chuang Li ◽  
Cheng Jia Shang ◽  
Chang An Zheng ◽  
Xin Lai He
Keyword(s):  
Cooling Rate ◽  
Rate Increase ◽  
Optical Microscope ◽  
Precipitation Process ◽  
Second Phase ◽  
Precipitation Behavior ◽  
Phase Form ◽  
Continuous Cooling ◽  
Bearing Steels ◽  
Hardness Tests

The precipitation behavior of several Cu-bearing steels with various copper contents during continuous cooling has been studied. The optical microscope and HRTEM were employed to study the influence of cooling rate on the precipitation process. Also, the hardness of samples with different processes is tested. The results show that when the steels was cooled at a cooling rate between 0.1-1°C/s with the cooling rate increasing the second phase precipitates become finer but the precipitates become denser. When the cooling rate is 1°C /s the density of the second phase precipitates are the largest. When the cooling rate is quicker than 1°C /s as the cooling rate increase the precipitates become finer and fewer. The hardness tests also show that the sample will get the highest hardness. When the samples are cooled at a rate larger than 5°C /s， there is few precipitates in samples. The copper-rich second phase form by Inter-phase precipitation, and the copper-rich phase i.e. G.P zone is the main cause to strengthen the alloy. As the copper content varies from 1.5wt% to 2.5wt% the highest hardness could be obtain when the samples is cooled at a rate of 1°C /s and the density of the precipitates is the largest

Hardenability of Medium Carbon Cr-Mn-Mo Alloyed Steels

2019 ◽  
Vol 946 ◽  
pp. 341-345
Author(s):  
Mikhail V. Maisuradze ◽  
Maksim A. Ryzhkov
Keyword(s):  
Cooling Rate ◽  
Structural Steels ◽  
Alloying Elements ◽  
Metallographic Analysis ◽  
Medium Carbon ◽  
Austenite Transformation ◽  
Continuous Cooling ◽  
Different Content ◽  
Cct Diagrams

Three medium carbon Cr-Mn-Mo structural steels with different content of alloying elements were studied. The austenite transformation during continuous cooling was investigated using dilatometer and metallographic analysis. The CCT diagrams were plotted showing the effect of the increased alloying elements content and B and Nb micro-alloying on the hardenability of the studied steels. The hardness dependences on the cooling rate were obtained.

Continuous Cooling Transformation of Overcooling Austenite and Structure Evolution of Si Steel

2013 ◽  
Vol 652-654 ◽  
pp. 947-951
Author(s):  
Hui Li ◽  
Yun Li Feng ◽  
Da Qiang Cang ◽  
Meng Song
Keyword(s):  
Phase Transformation ◽  
Cooling Rate ◽  
Optical Microscope ◽  
Structure Evolution ◽  
Upward Trend ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Hardness Tester ◽  
Gleeble 3500 ◽  
Evolution Of Microstructure

The static continuous cooling transformation (CCT)curves of 3.15 Si-0.036 C-0.21 Mn-0.008 S-0.008 N-0.022 Al are measured on Gleeble-3500 thermal mechanical simulator, the evolution of microstructure and the tendency of hardness are investigated by optical microscope (OM) and hardness tester. The results show that there is no evident change in microstructure which mainly are ferrite and little pearlite under different cooling rates, but the transition temperature of ferrite is gradually reduced with the increase of cooling rate. When the cooling rate is increased from 0.5°C/s to 20°C/s, the ending temperatures of phase transformation are decreased by 118°C, when cooling rate reaches to 10, Widmanstatten ferrite appears. The hardness of the steel turns out gradual upward trend with the increase of cooling rate.

Effect of Cooling Rate on the Precipitation Behavior of Carbonitride in Microalloyed Steel Slab

2010 ◽  
Vol 42 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Fanjun Ma ◽  
Guanghua Wen ◽  
Ping Tang ◽  
Guodong Xu ◽  
Feng Mei ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Microalloyed Steel ◽  
Precipitation Behavior ◽  
Steel Slab
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