A grain boundary etching method for the analysis of intergranular P-segregation in iron-based alloys

1984 ◽  
Vol 15 (8) ◽  
pp. 1563-1570 ◽  
Author(s):  
T. Ogura ◽  
A. Makino ◽  
T. Masumoto
Keyword(s):  
Grain Boundary ◽  
Etching Method ◽  
Iron Based

scholarly journals Entropy-Driven Grain Boundary Segregation: Prediction of the Phenomenon

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1331
Author(s):  
Pavel Lejček ◽  
Siegfried Hofmann
Keyword(s):  
Grain Boundary ◽  
Boundary Segregation ◽  
Indirect Evidence ◽  
Solute Segregation ◽  
Grain Boundary Segregation ◽  
Segregation Energy ◽  
Iron Based ◽  
Positive Segregation

The question is formulated as to whether entropy-driven grain boundary segregation can exist. Such a phenomenon would be based on the assumption that a solute can segregate at the grain boundary sites that exhibit positive segregation energy (enthalpy) if the product of segregation entropy and temperature is larger than this energy (enthalpy). The possibility of entropy-driven grain boundary segregation is discussed for several model examples in iron-based systems, which can serve as indirect evidence of the phenomenon. It is shown that entropy-driven grain boundary segregation would be a further step beyond the recently proposed entropy-dominated grain boundary segregation as it represents solute segregation at “anti-segregation” sites.

Depinning field of domain walls with a misaligned grain boundary in iron-based soft magnets

2016 ◽  
Vol 9 (5) ◽  
pp. 053003
Author(s):  
Keisuke Yamada ◽  
Shota Irie ◽  
Soh Murayama ◽  
Yoshinobu Nakatani
Keyword(s):  
Grain Boundary ◽  
Domain Walls ◽  
Soft Magnets ◽  
Iron Based ◽  
Depinning Field

Hydrogen Environment Embrittlement of Steels and Alloys In 70 MPa Hydrogen at Room Temperature

2006 ◽  
Author(s):  
Seiji Fukuyama ◽  
Masaaki Imade ◽  
Kiyoshi Yokogawa
Keyword(s):  
High Pressure ◽  
Grain Boundary ◽  
Stainless Steels ◽  
Room Temperature ◽  
Transgranular Fracture ◽  
Incoloy 800H ◽  
Grain Boundary Fracture ◽  
Iron Based ◽  
Boundary Fracture ◽  
Pressure Hydrogen

Hydrogen environment embrittlement (HEE) of steels and alloys to be used in high-pressure hydrogen storage for fuel cell vehicles was investigated in 70 MPa hydrogen at room temperature. Candidate materials for high-pressure hydrogen storage, namely, stainless steels (i.e., SUS304; in the Japanese Industrial Standard (JIS), SUS316, SUS316L, SUS316LN, SUS310S, SUS630(17-4PH)), a low-alloy steel (SCM440), carbon steels (SUY, S15C, S35C, S55C and S80C), an iron-based superalloy (SUH660(A286)), Ni-based superalloys (Incoloy 800H, Inconel 718, Inconel 750, Hastelloy B2, Hastelloy C22), a copper-zinc alloy (C3771) and an aluminum alloy (A6061), were tested. SWP (piano wire), and SUS304, SUS316 and SUS631(17-7PH) wires used for springs were also tested. Tensile tests were conducted at room temperature using specially designed apparatus developed by our laboratory to measure the actual load on a specimen with an external load cell irrespective of the axial load caused by the high pressure and friction at sliding seals. In materials that contain Ni, i.e., stainless steels, and iron-based and Ni-based superalloys, HEE shows a variable Ni content dependence. We found that the effect of Ni equivalent on HEE of these materials shows a stronger dependence. HEE decreases with increasing Ni equivalent with grain boundary fracture or transgranular fracture along a martensite lath assisted by hydrogen for SUS630, SUS304, SUS316, SUS316LN and SUS316L. No HEE is observed in the given Ni equivalent range with dimple fracture for SUH660, SUS310S and Incoloy 800H; however, HEE increases with increasing Ni equivalent with transgranular fracture along a slip plane, that is along the interface between austenite and gamma', and with grain boundary fracture assisted by hydrogen for Inconel 718, Inconel 750, Hastelloy C22 and Hastelloy B2. These results and other HEE test results in high-pressure hydrogen obtained by AIST, i.e., results for 18 Ni maraging steel, low-alloy steels, high-Cr steels, Ni-based superalloys; are summarized in the AIST HEE data, which is compatible with NASA HEE data. HEE of the materials in high-pressure hydrogen is discussed. Internal reversible hydrogen embrittlement (IRHE) of some thermally hydrogen-charged austenitic stainless steels is also discussed in comparison with HEE of the steels.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

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