Microstructural Observations of the Direct Quenched Offshore Steel

2017 ◽  
Vol 732 ◽  
pp. 55-58
Author(s):  
Chieh Yu ◽  
Ta Chien Cheng ◽  
Ren Kae Shiue ◽  
Tze Ching Yang ◽  
Ching Yuan Huang
Keyword(s):  
Retained Austenite ◽  
Vickers Microhardness ◽  
Iron Carbide ◽  
High Strength ◽  
Heat Treating ◽  
Carbide Formation ◽  
Tempered Martensite ◽  
Depth Profiles ◽  
Quenched Steel ◽  
Direct Quench

The purpose of this investigation is focused on the direct quench and temper mechanisms of the high strength offshore steel. Microstructural analyses of martensite and retained austenite in the direct quenched steel, simulations of martensitic transformation temperatures, Ms/Mf, and morphologies of bainite and ferrite have been evaluated in the experiment. Additionally, carbide formation after temped at various temperatures and microhardness depth profiles after heat treating are also included in the study. The direct quenched steel is primarily comprised of martensite, bainite and a few retained austenite with Vickers microhardness above 300. Tempered martensite, iron carbide and bainite are widely observed from all tempered specimens.

CRUCIBLE 422

Alloy Digest ◽  
2007 ◽  
Vol 56 (12) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Aerospace Industry ◽  
High Strength ◽  
Heat Treating ◽  
Tempered Martensite ◽  
Temperature Performance

Abstract Crucible 422 has a structure of tempered martensite to give the alloy high strength. It is useful in the aerospace industry for structurals with high strength/weight ratios. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on low and high temperature performance, and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-1004. Producer or source: Crucible Service Centers.

Influence of the Processing Variables on the Microstructure Evolution of a Bainitic Carbide-Free Steel

2016 ◽  
Vol 879 ◽  
pp. 867-872 ◽  
Author(s):  
M.C. Taboada ◽  
I. Gutiérrez ◽  
D. Jorge-Badiola ◽  
S.M.C. van Bohemen ◽  
F. Hisker ◽  
...  
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
High Volume ◽  
X Ray Diffraction ◽  
Tempered Martensite ◽  
Trip Steels ◽  
Volume Fractions ◽  
Advanced High Strength Steels ◽  
Processing Variables

New trends focused on achieving higher performance steels has led to a so-called 3rd Generation Advanced High Strength Steels (AHSS), in which the typical polygonal ferrite found in TRIP steels as a matrix phase is replaced by harder phases as Carbide-Free Bainite (CFB) and/or (tempered) martensite. Besides, large volume fractions of retained austenite (R.A.) with adequate stability are aimed for to improve the formability of the steels. Si containing steels are regarded as the most suitable to retard cementite formation and consequently reach high volume fractions of RA. In this work, CFB annealing schedules were applied to dilatometer samples of Fe-0.22C-2.0Mn-1.3Si. The overaging temperature TB was varied between 390 oC and 480 oC, and other processing variables investigated were the austenitizing temperature Taus, and the overaging holding time tB. The annealed samples analyzed with LOM, FEG-SEM, EBSD and X-ray diffraction techniques show that markedly different complex microstructures made up of bainite, ferrite, MA phase and retained austenite (R.A) are accomplished depending on the specific thermal cycle. These results are described in detail and discussed in relation to the dilatometry measurements.

scholarly journals Substructure Development and Damage Initiation in a Carbide-Free Bainitic Steel upon Tensile Test

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1261
Author(s):  
Mari Carmen Taboada ◽  
Amaia Iza-Mendia ◽  
Isabel Gutiérrez ◽  
Denis Jorge-Badiola
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Formation Mechanisms ◽  
Tempered Martensite ◽  
Damage Initiation ◽  
Advanced High Strength Steels ◽  
Significant Strength ◽  
The Stability

Carbide-free bainitic (CFB) steels belong to the family of advanced high strength steels (AHSS) that are struggling to become part of the third-generation steels to be marketed for the automotive industry. The combined effects of the bainitic matrix and the retained austenite confers a significant strength with a remarkable ductility to these steels. However, CFB steels usually show much more complex microstructures that also contain MA (Martensite–Austenite) phase and auto-tempered martensite (ATM). These phases may compromise the ductility of CFB steels. The present work analyzes the substructure evolution during tensile tests in the necking zone, and deepens into the void and crack formation mechanisms and their relationship with the local microstructure. The combination of FEG-SEM imaging, EBSD, and X-ray diffraction has been necessary to characterize the substructure development and damage initiation. The bainite matrix has shown great ductility through the generation of high angle grain boundaries and/or large orientation gradients around voids, which are usually found close to the bainite and MA/auto-tempered martensite interfaces or fragmenting the MA phase. Special attention has been paid to the stability of the retained austenite (RA) during the test, which may eventually be transformed into martensite (Transformation Induced Plasticity, or TRIP effect).

scholarly journals The Role of Retained Austenite in Tempered Martensite Embrittlement of 4340 and 300-M Steels Investigated through Rapid Tempering

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1349
Author(s):  
Virginia K. Euser ◽  
Don L. Williamson ◽  
Kip O. Findley ◽  
Amy J. Clarke ◽  
John G. Speer
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Austenite Decomposition ◽  
Tempered Martensite ◽  
Mechanical Transformation ◽  
Fresh Martensite ◽  
Rapid Tempering

Tempered martensite embrittlement (TME) is investigated in two medium carbon, high strength steels, 4340 (low silicon) and 300-M (high silicon), via rapid (1, 10, or 100 s) and conventional (3600 s) tempering. Rapid tempering of 4340 diminishes the depth of the TME toughness trough, where improvements in impact toughness correspond to the suppression of retained austenite decomposition. In 300-M, retained austenite decomposition is suppressed to an even greater extent by rapid tempering. While toughness improves overall after rapid tempering, TME severity remains consistent in 300-M across the tempering conditions examined. Through interrupted tensile tests, it was found that the 300-M conditions that exhibit TME are associated with mechanically unstable retained austenite. Unstable retained austenite is shown to mechanically transform early in the deformation process, presumably resulting in fresh martensite adjacent to interlath cementite that ultimately contributes to TME. The present results emphasize the role of both the thermal decomposition and mechanical transformation of retained austenite in the manifestation of TME.

Quenching and Partitioning of Ni-Added High Strength Steels

2007 ◽  
Vol 539-543 ◽  
pp. 4476-4481 ◽  
Author(s):  
F.C. Rizzo ◽  
A.R. Martins ◽  
John G. Speer ◽  
David K. Matlock ◽  
A. Clarke ◽  
...  
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Processing Parameters ◽  
Carbide Formation ◽  
X Ray Diffraction ◽  
Quenching And Partitioning ◽  
Steel Microstructure ◽  
Advanced High Strength Steels ◽  
Treatment Procedures

High strength steels containing significant fractions of retained austenite have been developed in recent years, and are the subject of growing commercial interest when associated with the TRIP phenomenon during deformation. A new process concept “quenching and partitioning” (Q&P) has been proposed by CSM/USA, and the results show the potential to create a new kind of steel microstructure with controlled amounts of retained austenite, enriched by carbon partitioning. Four steels containing C, Si, Mn, Ni, Cr and Mo, were designed with variation in the Ni and C content, aiming to decrease Bs temperature and to suppress carbide formation during the partitioning treatment. Several heat-treatment procedures were performed in specimens previously machined for tensile testing, while x-ray diffraction was used to determine the fraction of retained austenite. The tensile test results showed that except for the high C high Ni alloy, most of the processing conditions resulted in strengths superior to those of advanced high strength steels (AHSS), although it is importantly recognized that higher alloy additions were used in this study, in comparison with conventional AHSS grades.. A variety of strength and ductility combinations were observed, confirming the potential of the Q&P process and illustrating the strong influence of the final microstructure on the mechanical properties. Experimental results for samples partitioned at 400 °C indicate that higher ultimate tensile strength is associated with higher fraction of retained austenite for multiple heat treatments of each alloy investigated. The amount of retained austenite obtained was generally lower than that predicted by the model. Further studies are in progress to understand the influence of alloying and processing parameters (time/temperature) on the partitioning of carbon and precipitation of transition carbides.

The Effect of Tempering on Low-Temperature Toughness of the Direct Quenched High-Strength Offshore Steel

2017 ◽  
Vol 735 ◽  
pp. 49-53
Author(s):  
Ta Hung Tseng ◽  
Chieh Yu ◽  
Ren Kae Shiue ◽  
Tze Ching Yang ◽  
Ching Yuan Huang
Keyword(s):  
Low Temperature ◽  
High Strength ◽  
Tempering Temperature ◽  
Depth Profiles ◽  
Toughness Test ◽  
Tempering Treatment ◽  
Quenched Steel ◽  
Low Temperature Toughness

Microstructures, Vickers depth profiles and low-temperature toughness of the tempered direct water quenched steels have been evaluated in the experiment. Martensite dominates the direct quenched specimen, and it is brittle at low-temperature toughness test. The toughness of direct quenched steel is improved when it is tempered at 500 °C for 1800 s. However, increasing the tempering temperature from 500 °C to 660 °C has little effect on low-temperature toughness of the steel. The application of offshore steel must avoid bainite formation. Tempering treatment is very effective to improve low-temperature toughness of the martensite dominated structure.

The Effect of Si on the Toughness of High Strength Mn-Si-Cr Series Bainitic Steels

2005 ◽  
Vol 475-479 ◽  
pp. 213-216 ◽  
Author(s):  
Zhun Li Tan ◽  
Bing Zhe Bai ◽  
Hong Sheng Fang ◽  
Fu Bao Yang
Keyword(s):  
Silicon Content ◽  
Retained Austenite ◽  
High Strength ◽  
Onset Temperature ◽  
Tempered Martensite ◽  
Tempering Temperature ◽  
Minimum Value ◽  
Bainitic Steels ◽  
The Stability ◽  
The Relationship

The relationship between the toughness and silicon content of high strength Mn-Si-Cr series bainitic steels has been investigated. The results show that with increasing in silicon content, the onset temperature of the steel’s tempered martensite embrittlement (TME) rises; moreover, the minimum value of tested toughness decreases and the tempering temperature corresponding to the minimum value of toughness increases. This phenomenon results from the effect of silicon on the stability of filmy carbon-enriched retained austenite in carbide-free bainite/martensite (CFB/M) microstructure.

scholarly journals Designing Q&P Process for Experimental Steel with 0.47 % Carbon Content

2014 ◽  
Vol 887-888 ◽  
pp. 257-261 ◽  
Author(s):  
Vít Pileček ◽  
Hana Jirková ◽  
Bohuslav Mašek
Keyword(s):  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength ◽  
Heat Treating ◽  
Processing Parameters ◽  
Austenitizing Temperature ◽  
The Third ◽  
Martensitic Microstructure ◽  
The Impact ◽  
Correct Processing

The Q&P process (Quenching and Partitioning) is a heat treating method for high-strength low-alloyed steels. It delivers the desired combinations of high strength and adequate ductility. These properties are achieved thanks to the unique martensitic microstructure with a certain volume fraction of stable retained austenite. Retained austenite imparts plasticity to the otherwise brittle martensitic structure. Optimum mechanical properties are achieved by using correct processing parameters and chemistry of the material. The experimental material was a steel with 0.47 % carbon alloyed with silicon, manganese and chromium. The purpose of the effort was to optimise the heat treating parameters in order to obtain a strength level above 2000 MPa and an elongation of no less than 10%. In the first step, the appropriate austenitizing temperature was identified. In the second, effects of various quenching temperatures and cooling rates on the microstructure evolution were explored. In the third, the impact of raising the partitioning temperature on stabilization of retained austenite was examined. Adjustment of the parameters led to a strength of more than 2300 MPa and an elongation of 8 %.

SANICRO 41

Alloy Digest ◽  
1995 ◽  
Vol 44 (1) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Oil And Gas ◽  
High Strength ◽  
Heat Treating ◽  
Gas Production ◽  
Oil And Gas Production ◽  
Corrosion Resistant ◽  
Corrosion Resistant Alloy ◽  
Nickel Base

Abstract SANDVIK SANICRO 41 is a nickel-base corrosion resistant alloy with a composition balanced to resist both oxidizing and reducing environments. A high-strength version (110) is available for oil and gas production. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and joining. Filing Code: Ni-475. Producer or source: Sandvik.

CARLSON ALLOY C600 and C600 ESR

Alloy Digest ◽  
1994 ◽  
Vol 43 (11) ◽  
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Fracture Toughness ◽  
Cold Working ◽  
Elevated Temperatures ◽  
High Strength ◽  
Heat Treating ◽  
Solid Solution Alloy ◽  
Resistance To Oxidation ◽  
Good Workability

Abstract CARLSON ALLOYS C600 AND C600 ESR have excellent mechanical properties from sub-zero to elevated temperatures with excellent resistance to oxidation at high temperatures. It is a solid-solution alloy that can be hardened only by cold working. High strength at temperature is combined with good workability. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, and machining. Filing Code: Ni-470. Producer or source: G.O. Carlson Inc.

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