Metallurgical principles of microstructure formation in sub-zero treated cold-work tool steels – a review

2018 ◽  
Vol 106 (1) ◽  
pp. 104 ◽  
Author(s):  
Peter Jurči ◽  
Jana Ptačinová ◽  
Martin Sahul ◽  
Mária Dománková ◽  
Ivo Dlouhy
Keyword(s):  
Martensitic Transformation ◽  
Cold Work ◽  
The Other ◽  
Tool Steels ◽  
Conference Paper ◽  
Microstructure Formation ◽  
Wear Performance ◽  
The Past ◽  
Microstructural Effects ◽  
Isothermal Martensitic Transformation

The beneficial influence of a sub-zero treatment on wear resistant tools and components has been known for over 100 years. On the other hand, the basic metallurgical principles being responsible for enhanced hardness and wear performance, changes in the tempering response and toughness and improved dimensional stability have become known only over the past decade. The sub-zero treatment has, thus, been changed from an art to accepted science. The topic of the current conference paper is the latest theory explaining the metallurgical background for this kind of treatment. This theory states that it is the low-temperature isothermal martensitic transformation that induces secondary microstructural effects, such as an accelerated precipitation rate for transient carbides, formation of very small globular carbides and overall refinement of the microstructure. Consequently, secondary microstructural effects have a clear impact on the most relevant properties. The extent of the improvement or deterioration of these properties may be a result of competitive microstructural effects.

scholarly journals Microstructural effects on the fatigue crack nucleation in cold work tool steels

2010 ◽  
Vol 2 (1) ◽  
pp. 1777-1785 ◽  
Author(s):  
Ingrid Picas ◽  
Núria Cuadrado ◽  
Daniel Casellas ◽  
Alexey Goez ◽  
Luís Llanes
Keyword(s):  
Fatigue Crack ◽  
Crack Nucleation ◽  
Cold Work ◽  
Tool Steels ◽  
Fatigue Crack Nucleation ◽  
Microstructural Effects

Designing and assessing wheel/rail profiles for improved rolling contact fatigue and wear performance

2017 ◽  
Vol 231 (7) ◽  
pp. 805-818 ◽  
Author(s):  
Eric Magel ◽  
Joe Kalousek
Keyword(s):  
Infant Mortality ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
The Other ◽  
Wear Performance ◽  
The Past ◽  
Performance Of Systems ◽  
The World ◽  
Early Failures

A quick survey of wheel and rail profiles used around the world reveals a huge range of options. Wheels come in cylindrical, conical, and concave variations, while rails range in shape from a very flat 14 in. (350 mm) head radius to a tightly crowned 6 in. (150 mm) head radius. The rationale for implementing one or the other is often institutional inertia—a strong tendency to continue doing what has been done in the past. But the impacts of wheel and rail profiles on the performance of the vehicle/track interaction are large and the decision should not be made lightly. Unfortunately, there are few well-matched “off-the-shelf” solutions from the existing commercially available profiles, such that new rails and wheels often suffer early failures or infant mortality. Through examples and case studies, this paper discusses the significant role that wheel and rail profiles play with respect to performance and safety and makes the case for wheel and rail profiles specifically suited to the needs of each railway. Various techniques for assessing the performance of systems of wheels and rails are reviewed and discussed.

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

Applications of Through-Focus Dark Field Image Shifts to Phase Identification

1975 ◽  
Vol 33 ◽  
pp. 178-179
Author(s):  
Prakash Rao
Keyword(s):  
Dark Field Image ◽  
Thin Foil ◽  
Dark Field ◽  
The Other ◽  
Stereo Image ◽  
Phase Identification ◽  
The Past ◽  
Field Electron Microscopy ◽  
Dark Field Electron ◽  
Recent Extension

Image shifts in out-of-focus dark field images have been used in the past to determine, for example, epitaxial relationships in thin films. A recent extension of the use of dark field image shifts has been to out-of-focus images in conjunction with stereoviewing to produce an artificial stereo image effect. The technique, called through-focus dark field electron microscopy or 2-1/2D microscopy, basically involves obtaining two beam-tilted dark field images such that one is slightly over-focus and the other slightly under-focus, followed by examination of the two images through a conventional stereoviewer. The elevation differences so produced are usually unrelated to object positions in the thin foil and no specimen tilting is required.In order to produce this artificial stereo effect for the purpose of phase separation and identification, it is first necessary to select a region of the diffraction pattern containing more than just one discrete spot, with the objective aperture.

‘Newness which never perishes’? Schoenberg’s ambivalent reception of Haydn

2010 ◽  
Vol 51 (1-2) ◽  
pp. 215-224
Author(s):  
Alexander Carpenter
Keyword(s):  
The Other ◽  
Major Influence ◽  
Musical Style ◽  
The Past ◽  
Other Hand ◽  
The Future ◽  
Music Tradition

This paper explores Arnold Schoenberg’s curious ambivalence towards Haydn. Schoenberg recognized Haydn as an important figure in the German serious music tradition, but never closely examined or clearly articulated Haydn’s influence and import on his own musical style and ethos, as he did with many other major composers. This paper argues that Schoenberg failed to explicitly recognize Haydn as a major influence because he saw Haydn as he saw himself, namely as a somewhat ungainly, paradoxical figure, with one foot in the past and one in the future. In his voluminous writings on music, Haydn is mentioned by Schoenberg far less frequently than Bach, Mozart, or Beethoven, and his music appears rarely as examples in Schoenberg’s theoretical texts. When Schoenberg does talk about Haydn’s music, he invokes — with tacit negativity — its accessibility, counterpoising it with more recondite music, such as Beethoven’s, or his own. On the other hand, Schoenberg also praises Haydn for his complex, irregular phrasing and harmonic exploration. Haydn thus appears in Schoenberg’s writings as a figure invested with ambivalence: a key member of the First Viennese triumvirate, but at the same time he is curiously phantasmal, and is accorded a peripheral place in Schoenberg’s version of the canon and his own musical genealogy.

Economic Performance and Public Finance in Kenya, 1960-2010

2018 ◽  
Vol 47 (2) ◽  
Author(s):  
Kempe Ronald Hope
Keyword(s):  
Public Finance ◽  
Economic Performance ◽  
Emerging Economy ◽  
The Other ◽  
Government Investment ◽  
The Past ◽  
Other Hand ◽  
Private Savings ◽  
Per Capita ◽  
Real Growth

Countries with positive per capita real growth are characterised by positive national savings—including government savings, increases in government investment, and strong increases in private savings and investment. On the other hand, countries with negative per capita real growth tend to be characterised by declines in savings and investment. During the past several decades, Kenya’s emerging economy has undergone many changes and economic performance has been epitomised by periods of stability, decline, or unevenness. This article discusses and analyses the record of economic performance and public finance in Kenya during the period 1960‒2010, as well as policies and other factors that have influenced that record in this emerging economy. 

Kinetic Investigations of Boronized Cold Work Tool Steels

2014 ◽  
Vol 56 (2) ◽  
pp. 104-110 ◽  
Author(s):  
Polat Topuz ◽  
Eren Yılmaz ◽  
Emine Gündoğdu
Keyword(s):  
Cold Work ◽  
Tool Steels ◽  
Kinetic Investigations

LUKENS TOOL STEELS

Alloy Digest ◽  
1997 ◽  
Vol 46 (2) ◽  
Keyword(s):  
Tool Steel ◽  
Cold Work ◽  
Tool Steels ◽  
Steel Company ◽  
Full Size ◽  
Heat Treated

Abstract Lukens cold-work tool steels A2, D2, O1, S5, and S7 are used in applications where an air-hardening, oil-hardening, or shock-resisting tool steel is required. These steels are available in full-size, annealed plates suitable for saw cutting and/or finishing. Parts can subsequently be machined and heat treated to a range of hardness requirements. For improved internal cleanliness, all Lukens cold-work tool steels are produced with maximum sulfur levels of 0.010%. This datasheet provides information on composition. It also includes information on machining and joining. Filing Code: TS-550. Producer or source: Lukens Steel Company.

Vom Forst zum Wald. Entwicklungstendenzen im naturnahen Waldbau | From a Production-Oriented Forest to a Multipurpose Forest. New Trends in Near-Natural Silviculture

1999 ◽  
Vol 150 (12) ◽  
pp. 484-488 ◽  
Author(s):  
Wolf Hockenjos
Keyword(s):  
Forest Management ◽  
Timber Harvest ◽  
Timber Harvesting ◽  
Natural Forest ◽  
The Other ◽  
Private Forest ◽  
Wide Spread ◽  
Great Demand ◽  
The Past ◽  
Forest Enterprises

Concepts of near-natural forestry are in great demand these days. Most German forest administrations and private forest enterprises attach great importance to being as «near-natural» as possible. This should allow them to make the most of biological rationalisation. The concept of near-natural forestry is widely accepted, especially by conservationists. However, it is much too early to analyse how successful near-natural forestry has been to date, and therefore to decide whether an era of genuine near-natural forest management has really begun. Despite wide-spread recognition, near-natural forestry is jeopardised by mechanised timber harvesting, and particularly by the large-timber harvester. The risk is that machines, which are currently just one element of the timber harvest will gain in importance and gradually become the decisive element. The forest would then be forced to meet the needs of machinery, not the other way round. Forests would consequently become so inhospitable that they would bear no resemblance to the sylvan image conjured up by potential visitors. This could mean taking a huge step backwards: from a near-natural forest to a forest dominated by machinery. The model of multipurpose forest management would become less viable, and the forest would become divided into areas for production, and separate areas for recreation and ecology. The consequences of technical intervention need to be carefully considered, if near-natural forestry is not to become a thing of the past.

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