Bainite Formation at Low Temperatures in High C-Si Steel and its Mechanical Behavior

Cruz, José Alberto da; Rodrigues, T. F. M.; Viana, V. D. C.; Santos, Dagoberto Brandão

doi:10.4028/www.scientific.net/msf.706-709.173

Cited by 5 publications

(3 citation statements)

References 8 publications

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“…The past decade has seen increased research activity in the area of the so called superbainite or nanostructured bainite. [1][2][3][4][5][6][7] These microstructures are achieved through isothermal transformation to bainite (further referred to as bainitising) of high silicon steel grades with low martensite start temperature M s . This is a process similar to that already applied to steel grades such as 100Cr6 (see Table 1 for an example of composition or Ref.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of potential of high Si high C steel nanostructured bainite for wear and fatigue applications

Sourmail

Caballero

García‐Mateo

et al. 2013

Materials Science and Technology

110

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The present study is concerned with the potential of high carbon, high silicon steel grades isothermally transformed to bainite at low temperature (< 300 °C). A first part gives an overview of design principles allowing very high strength and ductility to be achieved, while minimising transformation duration. Wear and fatigue properties are then investigated for over ten variants of such material, manufactured in the laboratory or industrially. The results are discussed against published data. Tensile strength above 2 GPa are routinely achieved, with, in one case, an exceptional and unprecedented total elongation of over 20%. Bainite plate thickness and retained austenite content are shown to be important factors in controlling the yield strength, though additional, non negligible parameters remain to be quantified. Rolling-sliding wear performances are found to be exceptional, with as little as 1% of the specific wear rate of conventional bainitised 100Cr6. It is suggested that this results from the decomposition of retained austenite in the worn layer, which considerably increases hardness and presumaby introduces compressive residual stresses. Fatigue performance were slightly improved over 100Cr6 for one of the two industrially produced material, but significantly lower otherwise. Factors controlling fatigue resistance require further investigations.

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Section: Introductionmentioning

confidence: 99%

“…The past decade has seen increased research activity in the area of the so called superbainite or nanostructured bainite 1 – 7. These microstructures are achieved through isothermal transformation to bainite (further referred to as bainitising) of high silicon steel grades with low martensite start temperature M s .…”

Section: Introductionmentioning

confidence: 99%

Evaluation of potential of high Si high C steel nanostructured bainite for wear and fatigue applications

Sourmail

Caballero

García‐Mateo

et al. 2013

Materials Science and Technology

110

View full text Add to dashboard Cite

show abstract

“…In combination with the austenite that is retained, this gives a useful range of properties which have been exploited in the manufacture of armour [10]. There are other applications which are under active development: bearing manufacture [11], wear resistant surfacetreatments [12][13][14][15], shafts [16], automotive steel [17], sintered components [18], and the substitution of quenched and tempered steels [19].…”

Section: Introductionmentioning

confidence: 99%

Severe tempering of bainite generated at low transformation temperatures

Hasan

Peet

Bhadeshia

2012

International Journal of Materials Research

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The response of a strong bainitic-steel to tempering at high temperatures is investigated, because a softened state is sometimes necessary during the manufacture of engineering components, prior to the final heat-treatment which hardens the material. Thermodynamic calculations conducted to determine the maximum temperature at which the steel could be annealed without forming austenite were found to significantly overestimate the actual temperature at which austenite, ferrite and cementite (γ + α + θ) can coexist in equilibrium. As a consequence, the tempering temperature must be limited to below about 700 • C, which unfortunately necessitates many days of tempering in order to reduce the hardness to <250 HV. An alloy modification which may shorten this tempering time is suggested. One unexpected outcome is that the unintended heat treatment in the threephase field revealed useful information about the nucleation of pearlite on cementite particles. Colonies of pearlite started inevitably on particles of cementite located at the γ/α interfaces, rather than at similar particles enclosed completely by the austenite.

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Design of Novel Bainitic Steels: Moving from UltraFine to Nanoscale Structures

Caballero

García‐Mateo

Miller

2014

JOM

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The concepts of phase transformation theory can be exploited to design nanostructured steels that transform to bainite at temperatures as low as 150 ºC. The microstructure obtained is so refined that it is possible to achieve a strength in excess of 2.5 GPa in a material which has considerable toughness (40 MPam 1/2). Such combination of properties has never been achieved before with bainite. A description of the characteristics and significance of this remarkable microstructure in the context of the mechanism of transformation is provided. Advanced bainitic steels ready for the Nano Era There is a growing current awareness of the potential benefits of nanoengineering in the modern steel industry, and leading research and development institutes and companies are pursuing research in the area of nanostructured steels. In this industry, the term ultra-fine grained is generally used to describe steels with average grain sizes between 1 and 2 μm and the term submicron (submicrometre) structure to refer to grain sizes between 100 and 1000 nm. Until recently, effective processing techniques to reduce the grain size of these materials to less than 100 nm did not exist. There are major difficulties in creating novel nanostructures that have a combination of properties appropriate for large scale applications. An important requirement is to be able to manufacture large 3-dimensional nanostructured components. In addition, the material concerned must be cost effective to produce, if it is not to be limited to niche applications. Severe deformation by methods, such as mechanical milling, equal channel angular processing and high pressure torsional straining, has not succeeded in this respect. Although mechanical milling and alloying can produce powders containing nanosized grains, grain growth cannot effectively be suppressed during consolidation processes such as sintering and hot pressing. Therefore, processing bulk

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Bainite Formation at Low Temperatures in High C-Si Steel and its Mechanical Behavior

Cited by 5 publications

References 8 publications

Evaluation of potential of high Si high C steel nanostructured bainite for wear and fatigue applications

Evaluation of potential of high Si high C steel nanostructured bainite for wear and fatigue applications

Severe tempering of bainite generated at low transformation temperatures

Design of Novel Bainitic Steels: Moving from UltraFine to Nanoscale Structures

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