Effect of Cooling Rate on Microstructure of Simulated CGHAZ for Modified High-Cr Ferritic Heat-Resistant Steel

2011 ◽  
Vol 418-420 ◽  
pp. 1320-1323
Author(s):  
Xin Jie Di ◽  
Dan Xu ◽  
Yong Chang Liu
Keyword(s):  
Cooling Rate ◽  
Lath Martensite ◽  
Optical Microscope ◽  
Resistant Steel ◽  
Austenite Grain Size ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Δ Ferrite ◽  
Size And Morphology ◽  
Carbide Precipitate

The microstructure and carbide precipitate of simulated coarse grain heat affected zone(CGHAZ) in modified high Cr ferritic heat-resistant steel at different cooling rates have been investigated by means of thermal simulator, optical microscope, SEM and TEM . It was found that the microstructure of CGHAZ of testing steel was mainly lath martensite and δ-ferrite under the different welding thermal cycles. However, the prior austenite grain size reduced with increasing the cooling rate. Furthermore, with increasing the cooling rate, the amount of carbide precipitate inside laths of martensite increased, and the size and morphology of precipitates have changed from elongated and coarse to needlelike and fine.

Quench Brittleness of 12%Cr Martensitic Heat-Resistant Steel

2011 ◽  
Vol 479 ◽  
pp. 8-12 ◽  
Author(s):  
Gang Yang ◽  
Zheng Dong Liu ◽  
Shi Chang Cheng ◽  
Mu Xin Yang
Keyword(s):  
Impact Toughness ◽  
Cooling Rate ◽  
Microstructural Characterization ◽  
Temper Brittleness ◽  
Resistant Steel ◽  
Slow Cooling ◽  
Continuous Precipitation ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
The Impact

The mechanism of brittleness due to slow cooling during quenching was experimentally investigated in 12% Cr martensitic heat resistant steel. The mechanical property tests and microstructural characterization by SEM、TEM and XRD were conducted. The results showed the impact toughness would decrease with the slowing of cooling rate during quenching, and the low cooling rate within the temperature range from 820 to 660 °C played a significant effect on the impact toughness . Different from the mechanism of temper brittleness, the main causes of embrittlement due to the slow cooling upon quenching were both the continuous precipitation of M23C6 along prior austenite grain boundaries during the process of slow cooling and that of M2C along prior residual austenite film during tempering, and this kind of quench brittleness was nonreversal.

Effect of Austenitization Temperature on Phase Transition Features of High Cr Ferritic Heat-Resistant Steel

2012 ◽  
Vol 557-559 ◽  
pp. 175-181 ◽  
Author(s):  
Qiu Zhi Gao ◽  
Yong Chang Liu ◽  
Xin Jie Di ◽  
Li Ming Yu
Keyword(s):  
Magnetic Transition ◽  
Heating Process ◽  
Air Cooling ◽  
Resistant Steel ◽  
Magnetic Transition Temperature ◽  
Heat Resistant Steel ◽  
Austenitization Temperature ◽  
Heat Resistant ◽  
Δ Ferrite ◽  
Hot Rolled

The phase transformation of high Cr ferritic heat-resistant steel has been investigated by using differential scanning calorimeter and predicted by Thermo-calc calculation. The steel specimens were hot rolled and followed by air cooling, and then heated from room temperature up to different austenitization temperature as 800°C, 900°C, 1000°C and 1100°C. The DSC curves during heating process showed that the magnetic transition temperature and the Ac1 temperature are 744.9°C and 850.9°C, respectively. The austenitization range was about 58°C. The onset and offset temperature of martensite transformation both increase with the increase of austenitization temperature. The experimental results and the Thermo-calc calculated results both displayed that M23C6 carbides precipitated at around 950°C, and δ-ferrite started to form at about 1020°C.

The Corrosion Behavior of 9Cr Ferritic–Martensitic Heat-Resistant Steel in Water and Chloride Environment

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Z. Zhang ◽  
P. M. Singh ◽  
Z. F. Hu
Keyword(s):  
Grain Boundaries ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Optical Microscope ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Chloride Environment ◽  
Chloride Concentrations

The corrosion behavior of 9Cr ferritic–martensitic heat-resistant steel was investigated in water and chloride environment at room temperature (RT). The results of linear polarization, electrochemical impedance spectroscopy (EIS), and potentiodynamics (PD) polarization tests on long-term exposure show that 9Cr ferritic–martensitic steel has weaker corrosion resistance and greater pitting corrosion tendency in higher chloride concentrations. Corresponding scanning electron microscopy (SEM) observation displays that higher concentration chloride promotes the pitting initiation. During long-term exposure, pitting susceptibility decreases, the average pit size increases, and the density declines in higher chloride concentrations. Pits in the grains and along the grain boundaries are observed by optical microscope (OM), and it indicates that inclusions in grains and carbide particles at grain boundaries are the sites susceptible to pitting initiation.

Research of Aluminum Silicon Composite Layer on Heat Resistant Steel Grate by Cast-Infiltration Method

2013 ◽  
Vol 820 ◽  
pp. 34-37
Author(s):  
Zhen Wang ◽  
Hua Shun Yu ◽  
Xin Ying Wang ◽  
Lei Wang ◽  
Zhao Ding Song
Keyword(s):  
Composite Layer ◽  
Optical Microscope ◽  
Resistant Steel ◽  
Micro Hardness ◽  
Temperature Oxidation ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Carbide Particles ◽  
Infiltration Method ◽  
Aluminum Silicon

In order to improve the high temperature oxidation resistance, 75 Si-Fe and the silver paint were selected as cast-penetrated agent using the cast-infiltration method to form an aluminum silicon composite layer on the heat resistant steel grate surface. The microstructure and hardness properties of cast-infiltration layer were studied by optical microscope (OM), scanning electron microscope (SEM) with electron dispersive spectrum (EDS), and micro hardness test. The results show that the cast-infiltration layer is composed of ferrite and irregular shape of carbide particles. Most of the carbides are (Fe,Cr)3C and a small amount (Fe,Cr)7C3 also observed in composite layer. The highest micro hardness of fine carbide particles reaches 1253 HV. The optimized silicon content is 50wt%, and the thickness of infiltration layer reaches 0.6mm.

Analysis of dimple shape on fractographic heat-resistant steel images

2018 ◽  
Vol 2018 (46) ◽  
pp. 34-37
Author(s):  
I. B. Ivasenko ◽  
◽  
O. R. Berehulyak ◽  
R. A. Vorobel ◽  
◽  
...  
Keyword(s):  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant
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