The Use of Notch Specimens to Evaluate the Ductile to Brittle Transition Temperature; the Charpy Impact Test

2006 ◽  
pp. 135-154
Keyword(s):  
Transition Temperature ◽  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Brittle Transition ◽  
Brittle Transition Temperature ◽  
Ductile To Brittle Transition

scholarly journals Identification of ductile to brittle transition temperature by using plane strain specimen in tensile test and correlation with instrumented Charpy impact test: experimental and numerical study

2018 ◽  
Vol 19 (1) ◽  
pp. 107 ◽  
Author(s):  
Frank Tioguem ◽  
Matthieu Maziere ◽  
Franck Tankoua ◽  
André Galtier ◽  
Anne-Françoise Gourgues-Lorenzon
Keyword(s):  
Transition Temperature ◽  
Plane Strain ◽  
Numerical Study ◽  
Charpy Impact ◽  
Tensile Tests ◽  
Charpy Impact Test ◽  
Fracture Mechanisms ◽  
Brittle Transition ◽  
Brittle Transition Temperature ◽  
Ductile To Brittle Transition

This study addresses the correlation between the ductile-to-brittle transition temperature ranges of high strength 4140 steel obtained respectively from tensile tests under plane strain (PS) conditions and from conventional Charpy impact tests. Specimens were taken respectively at 25 mm (P) and at 55 mm (M) from skin of a cylindrical 90-mm-radius hot rolled bar water quenched from 875 °C, tempered at 600 °C and air cooled. P and M samples respectively showed a fully martensitic and a martensite-bainite microstructure. Fracture surface observations showed good agreement for physical fracture mechanisms (cleavage facet size, mixed ductile + brittle fracture in the transition region, ductile fracture at higher temperatures) between PS and Charpy, in particular sensitivity of upper bainite to cleavage fracture that reduces fracture energy in the lower self-energy on Charpy tests.

scholarly journals Mechanical Properties and Impact Toughness of Molybdenum Alloyed Ductile Iron

2020 ◽  
Author(s):  
D. Franzen ◽  
B. Pustal ◽  
A. Bührig-Polaczek
Keyword(s):  
Mechanical Properties ◽  
Transition Temperature ◽  
Ductile Iron ◽  
Calculated Data ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Brittle Transition ◽  
Brittle Transition Temperature ◽  
Ductile To Brittle Transition ◽  
High Silicon

Abstract Grades of high silicon ductile iron offer excellent combinations of static strength and ductility as well as good machinability due to their fully ferritic, solution strengthened matrix. As a result of elevated silicon contents, however, the ductile-to-brittle transition temperature in the Charpy impact test is significantly increased. Thus, minimum required Charpy impact energies cannot be met for many applications by using high silicon ductile iron. Therefore, alloys with lower strength and higher toughness properties are commonly used for many technical applications. The enormous lightweight construction potential of high silicon ductile iron can therefore not be fully exploited. The present investigation pursues the metallurgical approach of partially substituting silicon with molybdenum as an alternative strengthening element in order to improve the toughness properties while maintaining similar static mechanical properties. Molybdenum serves as a carbide-stabilising element in ductile iron, while simultaneously promoting ferrite formation and is therefore regarded to be suitable alloying element. In Charpy impact tests, the ductile-to-brittle transition temperature could be reduced by about 55 °C by reducing the silicon content to 2.95 wt% and adding 0.21 wt% molybdenum compared to a high silicon alloy. Additionally, it was possible to mathematically describe the transition behaviour of the studied alloys using nonlinear regression functions and to achieve a sufficient correlation of empirically determined and calculated data. This present metallurgical concept offers a promising metallurgical tool for further improving the toughness properties of alloyed ductile iron.

scholarly journals Ductile to brittle transition of an A508 steel characterized by Charpy impact test

2005 ◽  
Vol 72 (3) ◽  
pp. 413-434 ◽  
Author(s):  
B. Tanguy ◽  
J. Besson ◽  
R. Piques ◽  
A. Pineau
Keyword(s):  
Impact Test ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Brittle Transition ◽  
Ductile To Brittle Transition

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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