scholarly journals The Effect of Soaking on Segregation and Primary-Carbide Dissolution in Ingot-Cast Bearing Steel

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 800 ◽  
Author(s):  
Fareed Khan
Keyword(s):  
Bearing Steel ◽  
Primary Carbide ◽  
Substitutional Solute ◽  
The Matrix ◽  
Matrix Region ◽  
Steel Grades ◽  
Carbide Dissolution ◽  
Bulk Matrix ◽  
Primary Carbides ◽  
Composition Pattern

In this work, segregation in the cast and hot worked structure, as well as the effects of soaking on macro and micro segregation, in hypereutectoid bearing steel produced by ingot casting were studied. Samples were selected from ingots that where either as cast or soaked for twenty hours. Two similar bearing steel grades were used for this investigation. For the as cast ingot, samples were selected from both A-segregation channel regions and the matrix region. Samples were also selected from hot-worked bars originating from ingots that had been soaked for four hours or twenty hours. Micro and macro examinations of the microstructures were conducted and compared. In addition, a segregation analysis of the substitutional solute elements was performed using EDX equipment mounted on a Scanning Electron Microscope (SEM). EMPA mapping of the composition pattern in the bulk, as well as the carbides, was conducted. Precipitation of M3C, M2C, and M6C was observed. The carbides at A-segregation channels were found to have a different morphology to those precipitated in the bulk matrix. After soaking at 1200 °C for 4 h, all the primary carbides are dissolved.

Effect of prior cold ring rolling on carbide dissolution during the austenitizing process of an M50 bearing steel

2020 ◽  
Vol 10 (7) ◽  
pp. 1010-1019
Author(s):  
Jiao Su ◽  
Dongsheng Qian ◽  
Feng Wang
Keyword(s):  
Volume Fraction ◽  
Bearing Steel ◽  
Ring Rolling ◽  
Dissolution Behavior ◽  
Scanning Calorimetry ◽  
Cold Ring Rolling ◽  
The Matrix ◽  
Carbide Dissolution ◽  
The Mean ◽  
Kinetics Of

The influence of prior cold ring rolling (PCRR) on carbide dissolution during the austenitizing process of an M50 bearing steel was investigated by combining microstructural observations with kinetics analysis. The microstructural results show that the PCRR leads to a reduction in the volume fraction and the mean diameter of the undissolved carbides. The matrix of the as-quenched specimens after PCRR is enriched with more carbon and alloying elements than those without PCRR, which further confirms that the dissolution behavior of the alloy carbides is enhanced by PCRR during the austenitizing process. The kinetics of the transformation from ferrite to austenite (α → γ) without and with PCRR are determined by differential scanning calorimetry (DSC) upon heating. The austenite onset (Ac1) and end (Ac3) temperatures both decrease with as the thickness reduction from the PCRR increases. The activation energy for the α → γ transformation is calculated and shows a significant decline when the PCRR process is applied. In addition, the PCRR process results in a slight increase in the hardness regardless of the austenitizing temperature.

The Effects of Quenching and Tempering Treatment on the Hardness and Microstructures of a Cold Work Steel

2019 ◽  
Vol 4 (1) ◽  
pp. 286-294
Author(s):  
László Tóth ◽  
Réka Fábián
Keyword(s):  
Heat Treatment ◽  
Retained Austenite ◽  
Elevated Temperatures ◽  
Cryogenic Treatment ◽  
Cold Work ◽  
Chromium Steel ◽  
Primary Carbide ◽  
Tempering Temperature ◽  
Tempering Treatment ◽  
Primary Carbides

The X153CrMoV12 ledeburitic chromium steel characteristically has high abrasive wear resistance, due to their high carbon and high chromium contents with a large volume of carbides in the microstructure. This steel quality has high compression strength, excellent deep hardenability and toughness properties, dimensional stability during heat treatment, high resistance to softening at elevated temperatures. The higher hardness of cryogenic treated samples in comparison with conventional quenched samples mean lower quantity of retained austenite as at samples quenched to room temperature and tempered in similar condition. In the microstructure of samples were observed that the primary carbide did not dissolve at 1070°C and their net structure have not been changed during to heat treatment. During to tempering at high temperature the primary carbides have become more and more rounded. After low tempering temperature in martensite were observed some small rounded carbides also, increasing the tempering temperature the quantity of finely dispersed carbides increased, which result higher hardness. The important issues in heat treatment of this steels are the reduction or elimination of retained austenite due to cryogenic treatment.

scholarly journals On the Spheroidized Carbide Dissolution and Elemental Partitioning in High Carbon Bearing Steel 100Cr6

2013 ◽  
Vol 45 (2) ◽  
pp. 595-606 ◽  
Author(s):  
Wenwen Song ◽  
Pyuck-Pa Choi ◽  
Gerhard Inden ◽  
Ulrich Prahl ◽  
Dierk Raabe ◽  
...  
Keyword(s):  
Bearing Steel ◽  
High Carbon ◽  
Carbide Dissolution

The Relationship Between Magnetism and Microstructure of Ethylene Pyrolysis Furnace Tubes after a Long-term Service

2018 ◽  
Vol 24 (5) ◽  
pp. 478-487 ◽  
Author(s):  
Jingfeng Guo ◽  
Tieshan Cao ◽  
Congqian Cheng ◽  
Xianming Meng ◽  
Jie Zhao
Keyword(s):  
Saturation Magnetization ◽  
Outer Region ◽  
Cr Content ◽  
Pyrolysis Furnace ◽  
The Matrix ◽  
Furnace Tube ◽  
Primary Carbides ◽  
The Relationship ◽  
Very High

AbstractThe magnetism and microstructure of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes after 5 years of service were investigated in this paper. The saturation magnetization of the Cr25Ni35Nb alloy tube in the thickness direction is more than 20 emu/g, and the tube becomes ferromagnetic. The inner and outer walls of Cr35Ni45Nb alloy tubes also become ferromagnetic. But the saturation magnetization of the Cr35Ni45Nb alloy tubes approaches to zero in the center zone. The primary carbides M7C3 and NbC are changed into M23C6 and G phase at the outer region of the furnace tube. However, the M23C6-type carbides were replaced by carbon-rich carbides M7C3 at the carburization zone. Cr-depleted zones are formed at the inner and outer walls of the furnace tubes owing to oxidation. Carburization and oxidation reduce the Cr content of the matrix. Accordingly, the saturation magnetization is very high at the carburization zone and Cr-depleted zone. The magnetism of Cr25Ni35Nb and Cr35Ni45Nb alloy tubes has a high correlation with the Cr content of the matrix. Carburization and oxidation are the main reasons that make the paramagnetic ethylene pyrolysis furnace tube change to ferromagnetic.

Mechanics of the Segmentation of an Embedded Fiber, Part I: Experimental Investigations

1995 ◽  
Vol 62 (1) ◽  
pp. 87-97 ◽  
Author(s):  
A. ten Busschen ◽  
A. P. S. Selvadurai
Keyword(s):  
Structural Parameters ◽  
Matrix Material ◽  
Micromechanical Modeling ◽  
Experimental Investigations ◽  
Shear Stresses ◽  
Research Attention ◽  
Fragmentation Test ◽  
The Matrix ◽  
Matrix Region ◽  
Interface Bond

Micromechanical modeling is an important aspect in the study of fiber-reinforced composites. In such studies, an important class of structural parameters is formed by the interaction between the matrix and the embedded fibers. These interactive processes can be investigated by an appeal to a test which involves the segmentation of an embedded fiber. This test is referred to as a “fragmentation test.” During a fragmentation test, two distinct fracture phenomena are observed. These phenomena are directly related to the integrity of bond between the embedded fiber and the matrix. The first phenomenon involves situations where the interface bond is weaker than the matrix material. In this case the fiber fragment ends will slip and in this region shear stresses are transmitted by friction and/or interlocking mechanical actions. In contrast, when the interface bond has stronger properties than the matrix material, cracking will occur in the matrix region. Here, a crack initiated in the fiber will propagate into the matrix region typically forming conoidal cracks, or combinations of conoidal and flat cracks. This paper describes the background of the fragmentation test and the associated experimental research. Attention is focused on the experimental evaluation of matrix fracture topographies encountered in the fragmentation test.

Comportement au revenu d'un acier du type Z80CDSV8.2.1.1 pour cylindres de laminoirs à chaud

1996 ◽  
Vol 84 ◽  
pp. 3-12
Author(s):  
H. Djebaïli
Keyword(s):  
Magnetic Measurements ◽  
Residual Austenite ◽  
Progressive Increase ◽  
Continuous Heating ◽  
Preliminary Treatment ◽  
Hardness Testing ◽  
Physical Methods ◽  
The Matrix ◽  
Primary Carbides ◽  
Hot Hardness

Transformations in Cr-Mo-Si steels with a specific addition of Vanadium have been characterized precisely as well as their effect on the hardness of the materials. A preliminary treatment in the austenitic field leads to a limited enrichment of the matrix as well as temperature is less than 1050°C : only M3C and M23C6 carbides may then be dissolved. On the contrary, the dissolution of M7C3 and MC carbides is observed over 1100°C but is only partial even after treatment at 1150°C. After quenching from three distinct temperatures (1050-1100 and 1150°C), the microstructure consists of martensite, residual austenite and primary carbides (mainly M7C3 and MC type) ; different tempering treatments have been performed (isochronal, isothermal or on continuous heating) using various physical methods (dilatometry, DTA and magnetic measurements, TEM observations and hot hardness testing). According to the maximum θR temperature reached, the following structural evolutions were observed :•ε carbide precipitates at θR < 250° C in the a’ matrix, then M3C carbide forms between 250 and 350°C which transforms in M7C3 carbide from 450 to 500°C. At the same time (300- 500°C) a secondary hardening occurs linked to the formation of very fine V4C3 carbides : a progressive increase in hot hardness is observed while holding isothermally at 300-450°C.•From 450 to 600°C, the residual austenite is destabilized owing to the precipitation of small carbides in α'/γ interfaces and may be transformed on cooling either in bainite or secondary martensite. On the other hand that impoverished austenite may be transformed in (α + carbides) between 600-700°C. Besides in the same temperature range, M6C and M23C6 may be formed at the expense of fine M7C3 carbides previously formed.

scholarly journals The Effect of Thickness on the Properties of Laser-Deposited NiBSi-WC Coating on a Cu-Cr-Zr Substrate

Photonics ◽  
2019 ◽  
Vol 6 (4) ◽  
pp. 127
Author(s):  
Yury Korobov ◽  
Yulia Khudorozhkova ◽  
Holger Hillig ◽  
Alexander Vopneruk ◽  
Aleksandr Kotelnikov ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Matrix Material ◽  
Copper Substrate ◽  
Thin Layers ◽  
Laser Deposition ◽  
The Matrix ◽  
High Level ◽  
Primary Carbides ◽  
Matrix Powder ◽  
Wear Tests

Ni/60WC coatings on copper substrate were placed via laser deposition (LD). A structural study was conducted using electron microscopy and a microhardness evaluation. Two body abrasive wear tests were conducted with a pin-on-plate reciprocating technique. A tool steel X12MF GOST 5960 (C-Cr-Mo-V 1.6-12-0.5-0.2) with a hardness of 63 HRC was used as a counterpart. The following results were obtained: Precipitation of the secondary carbides takes place in the thicker layers. Their hardness is lower than that of the primary carbides in the deposition (2425 HV vs. 2757 HV) because they mix with the matrix material. In the thin layers, precipitation is restricted due to a higher cooling rate. For both LD coatings, the carbide’s hardness increases compared to the initial mono-tungsten carbide (WC)-containing powder (2756 HV vs. 2200 HV). Such a high level of microhardness reflects the combined influence of a low level of thermal destruction of carbides during laser deposition and the formation of a boride-strengthening phase from the matrix powder. The thicker layer showed a higher wear resistance; weight loss was 20% lower. The changes in the thickness of the laser deposited Ni-WC coating altered its structure and wear resistance.

Shear Localization and Microstructure Evolution in AlMgMnEr Alloy during Dynamic Deformation

2014 ◽  
Vol 915-916 ◽  
pp. 638-642
Author(s):  
Jia Ming Yin ◽  
Bo Long Li ◽  
Zuo Ren Nie
Keyword(s):  
Strain Rate ◽  
Microstructure Evolution ◽  
Dynamic Deformation ◽  
Shear Bands ◽  
Rolling Direction ◽  
Boundary Spacing ◽  
The Matrix ◽  
Matrix Region ◽  
Localized Shear Deformation ◽  
Gleeble 3500

The dynamic mechanical property and microstructure evolution in localized shear deformation was investigated in the Al-5.6%Mg-0.75%M-0.25%Er alloy cold rolled to 80% reduction by using Gleeble 3500 compression at the strain rate of 0.01~500s-1. The results show that both a critical strain rate and strain were required for the formation of local shear band under high strain rate compression. The initial Lamellar Boundaries (LBs) in the matrix region are parallel to the rolling direction (RD), with average boundary spacing of 0.25μm; The LBs within the shear bands region have a angle of 20° with RD, whose boundary spacing is ranging from 0.1 to 0.2μm. The LBs gradually rotate to an angle of 20° with RD and finally become wavy shape during the dynamic deformation.

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