Effect of continuous cooling rate on the precipitation of gamma prime in nickel-based superalloys

1995 ◽  
Vol 33 (4) ◽  
pp. 589-596 ◽  
Author(s):  
C.A. Klepser
Keyword(s):  
Cooling Rate ◽  
Continuous Cooling ◽  
Gamma Prime

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.

Continuous Cooling Transformation Behavior of High Carbon Pearlitic Steel

2022 ◽  
Vol 905 ◽  
pp. 83-87
Author(s):  
Lu Lu Feng ◽  
Wei Wen Qiao ◽  
Jian Sun ◽  
De Fa Li ◽  
Ping Ping Li ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Vickers Hardness ◽  
Hardness Test ◽  
Pearlitic Steel ◽  
Transformation Behavior ◽  
High Carbon ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Test Steel ◽  
Lamellar Pearlite

The continuous cooling transformation behavior of high-carbon pearlitic steel was studied by employing optical microscopy, scanning electron microscopy, and the Vickers hardness test. The results show that the microstructure of the test steel is composed of proeutectoid cementite and lamellar pearlite in the cooling rate range of 0.05–2 °C/s and lamellar pearlite in the range of 2–5 °C/s. Further, martensite appears at 10 °C/s. With the increase in the cooling rate, the Vickers hardness of the test steel first decreases and then increases. In the industrial production of high-carbon pearlite steel, the formation of proeutectoid cementite at a low cooling rate needs to be avoided, and at the same time, the formation of martensite and other brittle-phase at a high cooling rate needs to be avoided.

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.

Microstructure and Properties Formed at Different Cooling Rates of Low Carbon Alloy Steel for Welding Wire Production

2020 ◽  
Vol 304 ◽  
pp. 99-106
Author(s):  
Natalya Koptseva ◽  
Yulia Efimova ◽  
Mikhail Chukin ◽  
Alexander Pesin ◽  
N. Tokareva ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Physical Simulation ◽  
Low Carbon ◽  
Welding Wire ◽  
Continuous Cooling ◽  
Hardware Processing ◽  
Gleeble 3500 ◽  
Hot Rolled ◽  
Continuous Cooling Transformation Diagram ◽  
Undercooled Austenite

Physical simulation of steel Mn3Ni1CrMo continuous cooling with different speeds from austenitic state was performed using GLEEBLE 3500 complex. The phase transformations are analyzed and the effect of the cooling rate on the structure and hardness is investigated. A continuous cooling transformation diagram of the undercooled austenite decomposition is constructed. It was concluded that it is possible to reduce the hardness of the hot-rolled billet by reducing the cooling rate compared to the existing in the processing at the STELMOR line of PJSC “MMK”, and this will eliminate the heat treatment of welding wire on the hardware processing.

Ferritic Microstructures

2015 ◽  
pp. 113-131
Keyword(s):  
Carbon Atom ◽  
Cooling Rate ◽  
Classification System ◽  
Acicular Ferrite ◽  
Carbon Steels ◽  
Atom Diffusion ◽  
Continuous Cooling ◽  
Cooling Conditions ◽  
Induced Changes

This chapter describes the ferritic microstructures that form in carbon steels under continuous cooling conditions. It begins with a review of the Dubé classification system for crystal morphologies. It then explains how cooling-rate-induced changes involving carbon atom diffusion and the associated rearrangement of iron atoms produce the wide variety of morphologies and microstructures observed in ferrite. The chapter also describes a classification system developed specifically for ferritic microstructures and uses it to compare common forms of ferrite, including polygonal or equiaxed ferrite, Widmanstatten ferrite, quasi-polygonal or massive ferrite, acicular ferrite, and granular ferrite.

Continuous Cooling Phase Transformation Rules of High Nb X80 Pipeline Steel

2016 ◽  
Vol 850 ◽  
pp. 916-921
Author(s):  
Pei Pei Xia ◽  
Liu Qing Yang ◽  
Xiao Jiang Guo ◽  
Ye Zheng Li
Keyword(s):  
Phase Transformation ◽  
Cooling Rate ◽  
Acicular Ferrite ◽  
Thermal Deformation ◽  
Pipeline Steel ◽  
Phase Transformation Temperature ◽  
X80 Pipeline Steel ◽  
Continuous Cooling ◽  
Simulation Testing ◽  
Cooling Phase

The microstructural evolution of the high Nb X80 pipeline steel in Continuous Cooling Transformation (CCT) by Gleeble-3500HS thermal mechanical simulation testing system was studied, the corresponding CCT curves were drawn and the influence of some parameters such as deformation and cooling rate on microstructure of high Nb X80 pipeline steel was analyzed. The results show that as cooling rate increased, the phase transformation temperature of high Nb X80 steel decreased, with the microstructure transformation from ferrite-pearlite to acicular ferrite and bainite-ferrite. When cooling rate was between 20°C/s and 30°C/s, the microstructure was comparatively ideal acicular ferrite, thermal deformation accelerates phase transformation notably and made the dynamic CCT curves move upward and the initial temperature of phase transformation increase obviously. Meanwhile the thermal deformation refined acicular ferrite and extended the range of cooling rate accessible to acicular ferrite.

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 Phase Transformation Rule of 20CrMnTi Low-Carbon Alloy Steel

2019 ◽  
Vol 944 ◽  
pp. 303-312
Author(s):  
Li Zhang Li ◽  
He Wei ◽  
Lin Lin Liao ◽  
Yin Li Chen ◽  
Hai Feng Yan ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Cooling Rate ◽  
Vickers Hardness ◽  
Rolling Process ◽  
Transformation Rule ◽  
Low Carbon ◽  
Continuous Cooling ◽  
Starting Time ◽  
Ferrite Transformation ◽  
The Ideal

Gear steel is a ferritic steel. In the rolling process, the ideal structure is ferrite + pearlite, and bainite or martensite is not expected. However, due to the high alloy content, the hardenability is good, and the bainite or martensite structure is very likely to be generated upon cooling after rolling. In this paper, phase transformation rules during continuous cooling of 20CrMnTi with and without deformation were studied to guide the avoidance of the appearance of bainite or martensite in steel. A combined method of dilatometry and metallography was adopted in the experiments, and the dilatometer DIL805A and thermo-simulation Gleeble3500 were used. Both dynamic and static continuous cooling transformation (CCT) diagrams were drawn by using the software Origin. The causes of those changes in starting temperature, finishing temperature, starting time and transformation duration in ferrite-pearlite phase transformation were analyzed, and the change in Vickers hardness of samples with different cooling rate was discussed. The results indicate that with different cooling rate, there are three phase transformation zones: ferrite-pearlite, bainite and martensite. Deformation of austenite accelerates the occurrence of transformation obviously and moves CCT curve to left and up direction. When the cooling rate is lower than 1 °C/s, the phases in samples are mainly ferrite and pearlite, which is the ideal microstructure of experimental steel. As the cooling rate increases, starting temperature of ferrite transformation in steel decreases, starting time reduces, transformation duration gradually decreases, and the Vickers hardness of samples increases. Under the cooling rate of 0.5 °C/s, ferrite transformation in deformed sample starts at 751.67 °C, ferrite-pearlite phase transformation lasts 167.9 s, and Vickers hardness of sample is 183.4 HV.

scholarly journals Continuous Cooling Transformation of Under-Cooled Austenite of SXQ500/550DZ35 Hydropower Steel

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1562
Author(s):  
Zhenglei Tang ◽  
Ran Guo ◽  
Yang Zhang ◽  
Zhen Liu ◽  
Yuezhang Lu ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Hardness Measurement ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Continuous Cooling Transformation Diagrams ◽  
Transformation Diagrams ◽  
Hot Rolled ◽  
Vickers Hardness Measurement ◽  
Undercooled Austenite

The expansion curves of the continuous cooling transformation of undercooled austenite of SXQ500/550DZ35 hydropower steel at different heating temperatures and cooling rates were measured by use of a DIL805A dilatometer. Combined with metallography and Vickers hardness measurement, the continuous cooling transformation diagrams (CCT) of the studied steel under two different states were determined. The results show that in the first group of tests, after the hot-rolled specimens were austenitized at 920 °C, when the cooling rate was below 1 °C·s−1, the microstructure was composed of ferrite (F), pearlite (P) and bainite (B). With the cooling rates between 1 °C·s−1 and 5 °C·s−1, the microstructure was mainly bainite, and martensite (M) formed as the cooling rate reached 5 °C·s−1. When the cooling rate was up to 10 °C·s−1, the microstructure was completely martensite and the hardness value increased significantly. In the second group of tests, after the hot-rolled specimens were quenched at 920 °C and then heated at an intercritical temperature of 830 °C, in comparison with the first group of tests, and except for additional undissolved ferrites in each cooling rate range, the other microstructure types were basically the same. Due to the existence of undissolved ferrite, the microstructures of the specimens heated at intercritical temperatures were much finer, and the toughness values at low temperatures were better.

Sign in / Sign up

Export Citation Format

Share Document