Charpy impact energy, fracture toughness and ductile–brittle transition temperature of dual-phase 590 Steel

2007 ◽  
Vol 28 (2) ◽  
pp. 551-557 ◽  
Author(s):  
Y.J. Chao ◽  
J.D. Ward ◽  
R.G. Sands
Keyword(s):  
Fracture Toughness ◽  
Transition Temperature ◽  
Impact Energy ◽  
Charpy Impact ◽  
Dual Phase ◽  
Charpy Impact Energy ◽  
Brittle Transition ◽  
Ductile Brittle Transition Temperature ◽  
Brittle Transition Temperature

Microstructure-Toughness Relationship in AISI4340 Steel

2011 ◽  
Vol 312-315 ◽  
pp. 110-115
Author(s):  
N. Saeidi ◽  
A. Ekrami
Keyword(s):  
Transition Temperature ◽  
Charpy Impact ◽  
Brittle Transition ◽  
Hardness Tests ◽  
Ductile Brittle Transition Temperature ◽  
Different Temperatures ◽  
Ferrite Steel ◽  
Brittle Transition Temperature ◽  
Impact Data ◽  
Aisi4340 Steel

To improve the strength and toughness of AISI 4340 steel, different microstructures, containing full bainite, bainite-ferrite, martensite-ferrite and full martensite were produced by different heat treatment cycles. Tensile, impact and hardness tests were carried out at room temperature. The ductile-brittle transition temperature was determined from impact data at different temperatures. The results showed that steel with bainite - 0.34 ferrite microstructure has the highest elongation and charpy impact energy, while its tensile strength and yield stress decreased in comparison to other microstructures. This increment was noticeable when bainite - 0.34 ferrite steel was tempered. The ductile-brittle transition temperature decreased with tempering of bainite -0.34 steel. The fracture surface analysis of charpy specimens also showed an increase in toughness of tempered bainite-ferrite in comparison to other microstructures.

Evaluation of Ductile-Brittle Transition of Fracture Toughness by Material Degradation

2005 ◽  
Vol 297-300 ◽  
pp. 2465-2470 ◽  
Author(s):  
Chang Sung Seok ◽  
Hyung Ick Kim ◽  
Dae Jin Kim ◽  
Bong Kook Bae ◽  
Sang Pil Kim
Keyword(s):  
Fracture Toughness ◽  
Transition Temperature ◽  
Nuclear Power ◽  
Power Plants ◽  
Test Method ◽  
Fracture Toughness Test ◽  
Brittle Transition ◽  
Ductile Brittle Transition Temperature ◽  
Specimen Test ◽  
Brittle Transition Temperature

When huge energy transfer systems like nuclear power plants and steam power plants are operated for long times at high temperatures, mechanical properties change and ductile-brittle transition temperature increases by degradation. So we must estimate the degradation in order to assess safety, life expectancy, and other operation parameters. The sub-sized specimen test method using the surveillance specimen, and BI (Ball Indentation) method were developed for evaluating the integrity of metallic components. In this study, we will present the evaluation of the ductile-brittle transition temperature using the BI test and the sub-sized specimen test. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. The tensile test, the fracture toughness test, and the BI test were performed. The results of the fracture toughness tests using the sub-sized specimens were compared with those of the BI test. The evaluation technique of the ductile-brittle transition temperature using the BI test was also discussed. Our results show that the ductile-brittle transition temperatures rose as the aging time increased. We suggested that the fracture toughness results of the sub-sized specimen test and the IEF results of the BI test could be used in the estimation of the ductile-brittle transition temperature as material degrades.

Effects of Thermal Aging on Ductile-to-Brittle Transition Temperature Behavior of Welded A516 Steel

2011 ◽  
Vol 462-463 ◽  
pp. 1379-1384
Author(s):  
M.A. Khattak ◽  
M.A. Khan ◽  
Mohd Nasir Tamin
Keyword(s):  
Transition Temperature ◽  
Weld Metal ◽  
Impact Energy ◽  
Ductile Failure ◽  
Charpy Impact ◽  
Lower Bainite ◽  
Brittle Transition ◽  
Brittle Transition Temperature ◽  
Ductile To Brittle Transition ◽  
Temperature Exposure

Prolonged high temperature exposure of welded C-Mn steels is likely to cause microstructural changes leading to an inrease in the ductile-to-brittle transition temperature (DBTT) of the welded joint. Consequently, such degrading material properties should be quantified in view of establishing accurate component life prediction model. This study examined effects of isothermal aging on DBTT behavior of the heat affected zone (HAZ) in welded Type A516 Gr 70 steels. Microstructures of the as-received weld region revealed the presence of pearlite and ferrite in the base metal while upper and lower bainite are found in the HAZ and weld metal, respectively. Hardness measures for the weld metal region, HAZ and base steel are 172, 209 and 150, respectively. Aging at 420 oC, 500 hours lowers hardness value of the HAZ by 20 %. A series of Charpy impact tests on V-notched specimens are performed for as-received and thermally aged samples at 420 oC for 500, 800 and 1200 hours. Results showed that the absorbed impact energy displays a sigmoidal variation with test temperatures. DBTT ranges from -60 to 5 oC for HAZ while narrow range from -25 to 12 oC for weld metal region. Absorbed impact energy variations in samples aged for durations up to 800 hours display another saturation level over test temperatures between -30 to 10 oC. Fractographic analysis on HAZ fracture surface indicated brittle fracture at -60 oC while ductile failure dominated at 27.7 oC. A mix-mode fracture mechanism is displayed for test conducted at -38 oC.

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