Grain Boundary Segregation Behavior in 2.25Cr-1Mo Steel During Reversible Temper Embrittlement

Islam, Mahbubul

doi:10.1007/s11665-006-9011-1

Cited by 14 publications

(3 citation statements)

References 13 publications

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“…According to previous reports, the fracture toughness value evaluated by three point bending tests in accordance with BS7448 in tempered martensitic steel is 30.8 MPam 1/2 . 16) Compared with the previous value, the value calculated here is lower. Whereas the previous study evaluated the entire fracture toughness values of multiple prior £-grain boundaries, this study evaluated the fracture toughness of one prior £-grain boundary.…”

Section: Resultscontrasting

confidence: 67%

Low-Temperature Micro-Fracture Toughness Testing of Grain Boundaries in Steel

Shimada¹,

Harada

Mine

et al. 2021

Mater. Trans.

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Temper embrittlement in high-strength steel occurs due to the segregation of impurity elements along prior austenite (£) grain boundaries, resulting in a decrease in intergranular strength. However, the grain boundary properties have not yet been experimentally investigated. In this study, we developed a micro testing method to selectively process micro-cantilever specimens based on a specific prior £-grain boundary to measure the grain boundary fracture toughness. Fracture toughness tests using micro-cantilever specimens with side grooves and notch were carried out at 183 K and brittle fracture behavior was successfully obtained. The fracture surface showed almost flat and brittle crack propagation along the prior £-grain boundary. The derived fracture toughness value, K Q , is lower than that from previous values. By employing this method for the evaluation of intergranular fractures in steel, we believe that we can evaluate more intrinsic prior £-grain boundary properties compared with conventional methods.

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Section: Resultscontrasting

confidence: 67%

Low-Temperature Micro-Fracture Toughness Testing of Grain Boundaries in Steel

Shimada¹,

Harada

Mine

et al. 2021

Mater. Trans.

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“…The cracks were found only in the CGHAZ and occurred by grain boundary decohesion, giving a fracture surface that resembles a low-temperature brittle fracture. Normal mode of fracture in low C-CrMoV steel is transgranular, but in this case, the fracture was found to be brittle intergranular which indicates that the grain boundaries were weakened due to some reason [5]. Main source of grain boundary weakening in low alloy steels is segregation of P, S, As, Sb, Sn, etc., to the prior austenite grain boundaries.…”

Section: Discussionmentioning

confidence: 85%

Failure Analysis of HAZ Cracking in Low C–CrMoV Steel Weldment

Naz

Tariq

Baloch

2009

J Fail. Anal. and Preven.

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This case study describes the failure analysis of steel nozzle in which cracking was observed after a circumferential welding process. The nozzle assembly was made from low C-CrMoV alloy steel that was subsequently single pass butt welded using gas tungsten arc welding. No cracks were found in visual inspection of the welds; however, X-ray radiography showed small discontinuous cracks on the surface in the area adjacent to weld bead, i.e. heat affected zone. The welding of nozzle parts made of same material was a routine process and this type of cracking did not occur in the past. Therefore, it became essential to determine the root cause of the failure. A detailed investigation including visual examination, nondestructive testing, optical microscopy, microhardness measurements and residual stress measurements were carried out to find out the primary cause of failure and to identify actions required to avoid its reoccurrence in future. Results of the investigation revealed that the principal cause of failure was the presence of coarse untempered martensite in the heat affected zone due to localized heating. The localized heating was caused by high welding heat input or low welding speed and resulted in the high transformation stresses. These transformation stresses combined with the thermal stresses and the constraint conditions to cause intergranular brittle fracture.

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“…Step cooling heat treatment was conducted on part of the weld joint to simulate the in-service phosphorus segregation on an accelerated basis [9,21,22]. The sequence for this treatment was 593ºC/1 h → 538ºC/15 h → 524ºC/24 h → 496ºC/48 h → 468ºC/125 h.…”

Section: Materials and Thermal Treatmentsmentioning

confidence: 99%