The role of actively diffusing impurities of sulfur and oxygen in ductility-dip cracking susceptibility of Ni-Cr-Fe welds

2018 ◽  
Vol 2 (89) ◽  
pp. 49-55 ◽  
Author(s):  
K.A. Yushchenko ◽  
A.V. Zviagintseva ◽  
L.M. Kapitanchuk ◽  
I.S. Gakh
Keyword(s):  
Solid Solution ◽  
Grain Boundary ◽  
Sample Surface ◽  
Formation Of Cracks ◽  
Boundary Model ◽  
Heating Up ◽  
Impurity Elements ◽  
Content Design

Purpose: To determine the temperature conditions of sulphur and phosphorus moving to sample surface for alloys with different initial sulphur content. Design/methodology/approach: Investigation of samples from In 690, Kh20N16AG6, In52MSS alloys in Auger spectrometer JAMP-9500F for determination of the probability of saturation of the free surface (as grain boundary model) with sulphur from the solid solution. Results obtained without removing the samples from the chamber, stage-by-stage heating up to 800°C with determination of element content every 100°C. Findings: It is shown that sulphur has the tendency of diffusing to the interface from the middle of the grain body and forming segregations in the form of a monolayer even at its slight (0.00015 wt.%) content in the alloy. Research limitations/implications: Presence of actively diffusing impurities (C, O, H, S, P), dissolved in the metal, in the case of a gradient of temperatures and stresses, leads to redistribution of these impurities between the solid solution and surface of the sample, or solid solution and grain boundaries (interface). According to the obtained data, change of elemental composition proceeds within 0.5-1 nm from the grain boundary or from the sample surface and leads to formation of monolayers. Practical implications: To prevent the formation of cracks it is necessary not only to reduce the content of impurity elements in the alloy, but to prevent moving them to the boundary of grains and creating mono layers. Originality/value: For the selected alloys, the formation of monolayers is the most intensive at temperatures of 700-800° that coincides with DTR in the temperature range of 0.6-0.8 Ts. Such monolayers can lead to ductility dip cracks formation.

Determination of the Content of Ultra-Low Sulphur in PM Superalloy FGH96 by Infrared Carbon-Sulphur Detector

2013 ◽  
Vol 634-638 ◽  
pp. 1821-1825
Author(s):  
Jian Huan Wei ◽  
Wei Cao ◽  
Yong Zhang
Keyword(s):  
Grain Boundary ◽  
Fatigue Property ◽  
Market Demand ◽  
Analysis Techniques ◽  
Test Conditions ◽  
Turbine Disc ◽  
Quantity Control ◽  
Impurity Elements ◽  
Pm Superalloy

PM Superalloy FGH96 is usually used as turbine disc materials. It is a kind of alloy with high purity, which has strict demands of the content of impurity elements, especially the element of sulphur. Because sulphur is accumulated in the grain boundary of manganese or iron, with the form of sulfide, it has great impact on the performance of PM Superalloy FGH96, such as toughness and fatigue property. Therefore, it is an important part of quantity control to detect accurately of the content of ultra-low sulphur in PM Superalloy FGH96. As the market demand of PM Superalloy FGH96 and quality becomes varied, it is a trend that PM Superalloy FGH96 has ultra-low content of sulphur (S: 0.0001%-0.0020%). Hence, the related analysis techniques are needed. A new method of analyzing Ultra-low Sulphur (S: 0.0001%-0.0020%) in PM Superalloy FGH96 is established in the article by selective experiments with relevant test conditions, such as combustion conditions and blank test, using infrared carbon-sulphur detector.

The influence of phosphorus in dilute solid solution on the absolute surface and grain boundary energies of iron

1965 ◽  
Vol 286 (1407) ◽  
pp. 479-498 ◽  
Keyword(s):  
Solid Solution ◽  
Grain Boundary ◽  
Phosphorus Content ◽  
Diffusion Creep ◽  
Self Diffusion ◽  
Thin Foils ◽  
The Absolute ◽  
Contractile Forces

A technique has been developed for the determination of the absolute surface energies of iron and iron alloys at temperatures of up to the melting point. The technique is based upon the measurement of the contractile forces in thin foils. All measurements are made in situ and chemical equilibrium is maintained throughout the experiment. The results show that phosphorus in dilute solid solution decreases progressively the surface energy of iron at 1450 °C from 2100 ergs cm -2 to 1200 ergs cm -2 , for increasing phosphorus contents of up to 0.36%. Results were also obtained for the γ phase in which the effect is less pronounced. Absolute grain boundary energies were also determined as a function of phosphorus content. From the strain rate of the foils which move by a diffusion creep mechanism, it was deduced that the self diffusion coefficient increases linearly with phosphorus content. Application of the Gibbs adsorption theorem has permitted the evaluation of the extents of equilibrium segregation of the solute to interfaces. The maximum levels are 2.3 x 10 -9 g-atom cm -2 at surfaces and 1.1 x 10 -9 g-atom cm -2 at grain boundaries. The relevance of these measurements to the problem of the intergranular brittle fracture of iron/phosphorus alloys is discussed.

Failure of Stretched Rubbers under the Influence of Ozone

1956 ◽  
Vol 29 (2) ◽  
pp. 568-572
Author(s):  
Yu S. Zuev ◽  
A. S. Kuzminskiĭ
Keyword(s):  
Experimental Data ◽  
Structure Formation ◽  
Fundamental Cause ◽  
Formation Of Cracks ◽  
Clear Idea

Abstract Cracks perpendicular to the axis of stretching rapidly appear on stretched or bent rubbers exposed to the atmosphere (in the case of loaded vulcanized polybutadiene in the spring and summer months, in a few days). The fundamental cause of this phenomenon is the action of the ozone which is always present in the atmosphere in concentrations of several millionths of a per cent. However, we still lack any clear idea of the mechanism of this phenomenon, which would make possible a rational determination of ways to protect rubber. Questions related to the mechanism of ozone cracking of rubbers are discussed in this article on the basis of new experimental data. Causes of the formation of cracks. The presence of a stress is an indispensable condition for ozone deterioration. It is believed that the role of the stress can be summed up as follows. 1. The rubber molecules, under the influence of stress, are activated with respect to ozone. 2. The stress modifies the relation between the processes of structure formation and destruction in favor of the latter. For example, the stress may facilitate rupture of the chains during regrouping of the initial unstable ozonide into isoozonide.

scholarly journals The Significance of Entropy in Grain Boundary Segregation

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 492 ◽  
Author(s):  
Pavel Lejček ◽  
Siegfried Hofmann ◽  
Václav Paidar
Keyword(s):  
Grain Boundary ◽  
Materials Science ◽  
Boundary Segregation ◽  
Decisive Role ◽  
Grain Boundary Segregation ◽  
Bcc Iron ◽  
Boundary Chemistry ◽  
Materials Behavior

The role of entropy in materials science is demonstrated in this report in order to establish its importance for the example of solute segregation at the grain boundaries of bcc iron. We show that substantial differences in grain boundary chemistry arise if their composition is calculated with or without consideration of the entropic term. Another example which clearly documents the necessity of implementing the entropic term in materials science is the enthalpy-entropy compensation effect. Entropy also plays a decisive role in the anisotropy of grain boundary segregation and in interface characterization. The consequences of the ambiguous determination of grain boundary segregation on the prediction of materials behavior are also briefly discussed. All the mentioned examples prove the importance of entropy in the quantification of grain boundary segregation and consequently of other materials properties.

Intergranular embrittlement in CrMoV steels: an assessment of the effects of residual impurity elements on high temperature ductility and crack growth

1980 ◽  
Vol 295 (1413) ◽  
pp. 235-251 ◽  
Keyword(s):  
High Temperature ◽  
Stress Relief ◽  
Service Work ◽  
Contributory Factor ◽  
Relative Importance ◽  
Residual Impurity ◽  
Intergranular Embrittlement ◽  
Formation Of Cracks ◽  
Impurity Elements

Examination of the causes of cracking in the heat-affected zones of welded joints in CrMoV steels during stress relief or operation at elevated temperature has shown that the presence of certain residual impurity elements is an important contributory factor. A detailed study of the effects of the elements P, As, Sn, Sb and Cu on the high temperature ductility and crack propagation behaviour of heat-affected zone microstructures in 1/2 Cr 1/2 Mo 1/4 V steel has been carried out to provide information on the role of these elements in the formation of cracks during stress relief and their growth in service. Work on experimental alloys has identified the relative importance of individual elements in promoting intergranular embrittlement; comparison is made with the behaviour of commercial steels. The results are discussed in terms of a possible embrittlement mechanism and consideration is given to the practical measures available for preventing cracking, both in terms of residual element and microstructure control.

scholarly journals The Role of Grain Boundary Oxidation on Surface Crack Formation under Continuous Casting Conditions

2019 ◽  
Vol 164 (11) ◽  
pp. 461-465 ◽  
Author(s):  
Roman Krobath ◽  
Christian Bernhard ◽  
Sergiu Ilie ◽  
Jakob Six ◽  
Susanne Hahn ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Continuous Casting ◽  
Tensile Deformation ◽  
Stress Concentrations ◽  
Critical Temperatures ◽  
Formation Of Cracks ◽  
Testing Condition ◽  
Holding Temperature

Abstract This paper represents an extended abstract of a study presented at the ESTAD 2019 conference. In this contribution, the influence of different cooling strategies on the formation of intergranular surface cracks is observed with in-situ bending experiments under continuous casting conditions. The steel composition is equal to a 0.17 wt.% C construction steel. It is investigated with and without Al deoxidation at bending temperatures of 1100 °C to 700 °C. The results show the most critical situation prevailed for each testing condition at 900 °C. A holding temperature of 1200 °C leads to a selective grain boundary oxidation and therefore to the formation of notches at the austenite grain boundaries, which are the cause for stress concentrations and easier formation of cracks during a subsequent tensile deformation at critical temperatures. The experiments reveal a partially stronger influence of this phenomenon on the steel without Al deoxidation.

Strain-induced martensite effects on transgranular carbide precipitation in type 304 stainless steels

1991 ◽  
Vol 49 ◽  
pp. 604-605
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D. Matlock
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Deformation Twin ◽  
Austenitic Stainless Steels ◽  
Carbide Precipitation ◽  
Strain Induced Martensite ◽  
Type 304

Thermomechanically induced strain is a key variable producing accelerated carbide precipitation, sensitization and stress corrosion cracking in austenitic stainless steels (SS). Recent work has indicated that higher levels of strain (above 20%) also produce transgranular (TG) carbide precipitation and corrosion simultaneous with the grain boundary phenomenon in 316 SS. Transgranular precipitates were noted to form primarily on deformation twin-fault planes and their intersections in 316 SS.Briant has indicated that TG precipitation in 316 SS is significantly different from 304 SS due to the formation of strain-induced martensite on 304 SS, though an understanding of the role of martensite on the process has not been developed. This study is concerned with evaluating the effects of strain and strain-induced martensite on TG carbide precipitation in 304 SS. The study was performed on samples of a 0.051%C-304 SS deformed to 33% followed by heat treatment at 670°C for 1 h.

On the role of tin underlays for the prevention of thermal grooving in thin gold films

1986 ◽  
Vol 44 ◽  
pp. 732-733
Author(s):  
Jin Young Kim ◽  
R. E. Hummel ◽  
R. T. DeHoff
Keyword(s):  
Thin Film ◽  
Free Surface ◽  
Grain Boundary ◽  
Beneficial Effect ◽  
Failure Mechanism ◽  
Failure Mechanisms ◽  
Distinct Advantage ◽  
Gold Films ◽  
Gold Thin Film

Gold thin film metallizations in microelectronic circuits have a distinct advantage over those consisting of aluminum because they are less susceptible to electromigration. When electromigration is no longer the principal failure mechanism, other failure mechanisms caused by d.c. stressing might become important. In gold thin-film metallizations, grain boundary grooving is the principal failure mechanism.Previous studies have shown that grain boundary grooving in gold films can be prevented by an indium underlay between the substrate and gold. The beneficial effect of the In/Au composite film is mainly due to roughening of the surface of the gold films, redistribution of indium on the gold films and formation of In2O3 on the free surface and along the grain boundaries of the gold films during air annealing.

A Molecular Approach to Immunoscintigraphy: A Study of the T-Antigen Conformation on the Surface of Tumors

1987 ◽  
Vol 26 (01) ◽  
pp. 1-6 ◽  
Author(s):  
S. Selvaraj ◽  
M. R. Suresh ◽  
G. McLean ◽  
D. Willans ◽  
C. Turner ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Tumor Cell ◽  
T Antigen ◽  
Human Carcinomas ◽  
Animal Tumor ◽  
Synthetic Antigens

The role of glycoconjugates in tumor cell differentiation has been well documented. We have examined the expression of the two anomers of the Thomsen-Friedenreich antigen on the surface of human, canine and murine tumor cell membranes both in vitro and in vivo. This has been accomplished through the synthesis of the disaccharide terminal residues in both a and ß configuration. Both entities were used to generate murine monoclonal antibodies which recognized the carbohydrate determinants. The determination of fine specificities of these antibodies was effected by means of cellular uptake, immunohistopathology and immunoscintigraphy. Examination of pathological specimens of human and canine tumor tissue indicated that the expressed antigen was in the β configuration. More than 89% of all human carcinomas tested expressed the antigen in the above anomeric form. The combination of synthetic antigens and monoclonal antibodies raised specifically against them provide us with invaluable tools for the study of tumor marker expression in humans and their respective animal tumor models.

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