Investigation of Lath and Plate Martensite in a Carbon Steel

Martensite in carbon steels forms in different morphologies, often referred to as lath andplate martensite. The alloy composition has a strong effect on the morphology, for instance in car-bon steels there is a morphological change of the martensite microstructure from lath martensite atlow carbon contents to plate martensite at high carbon contents. In the present work a decarburizedhigh-carbon steel, enabling the isolation of carbons' influence alone, has been studied in order to in-vestigate the changes in morphology and hardness. From the results it is concluded that there is acontinuous change of hardness with increased carbon content. The increasing hardness slows down atabout 0.6 wt%C before decreasing at higher carbon contents. This is in accordance with the change inmorphology since it was found that lath martensite dominates below 0.6 wt%C and the first units ofgrain boundary martensite and plate martensite appear above 0.6 wt%C. At high carbon contents thedominating morphology is plate martensite, but retained austenite is also present.

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Morphology, Nature and Formation Mechanism of Packet Plate Martensite in Medium and High Carbon Steels

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.121-126.231 ◽

2011 ◽

Vol 121-126 ◽

pp. 231-238 ◽

Cited By ~ 1

Author(s):

Yue Xin Ma ◽

Yue Jun Liu ◽

Long Wang ◽

De Chang Zeng ◽

Yu Hua Tan

Keyword(s):

Twin Boundary ◽

Misorientation Angle ◽

Martensite Transformation ◽

Lath Martensite ◽

Carbon Steels ◽

Plate Martensite ◽

Low Carbon ◽

High Carbon ◽

Boundary Misorientation ◽

Carbon Martensite

The microstructures of 11 kinds of commercial steels quenched from high temperature were deeply studied by optical microscope and canning election microscope. It was proved that packet martensite in medium and high carbon steels is not lath martensite, but rather packet plate martensite. Through the analysis of crystallography，it was found that four change rules of crystal orientation may arise during the process of martensite transformation. Two inner interfaces spontaneously formed were only discovered in martensite transformation process: small-angel boundary (misorientation angle is 0 ~ 10º) and twin boundary (misorientation angle is 70º32’). The former mainly appeared in low carbon martensite, and the latter principally formed in medium and high carbon martensite. The twin boundary packet mechanism in medium and high carbon steels has made in detail in this paper.

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Mechanism of the Microstructural Evolution of 18Cr2Ni4WA Steel during Vacuum Low-Pressure Carburizing Heat Treatment and Its Effect on Case Hardness

Materials ◽

10.3390/ma13102352 ◽

2020 ◽

Vol 13 (10) ◽

pp. 2352

Author(s):

Bin Wang ◽

Yanping He ◽

Ye Liu ◽

Yong Tian ◽

Jinglin You ◽

...

Keyword(s):

Low Temperature ◽

Carbon Content ◽

Retained Austenite ◽

Mechanical Stability ◽

Lath Martensite ◽

Low Pressure ◽

Low Carbon ◽

High Carbon ◽

Carburized Layer ◽

Martensite Matrix

In this study, vacuum low-pressure carburizing heat treatments were carried out on 18Cr2Ni4WA case-carburized alloy steel. The evolution and phase transformation mechanism of the microstructure of the carburized layer during low-temperature tempering and its effect on the surface hardness were studied. The results showed that the carburized layer of the 18Cr2Ni4WA steel was composed of a large quantity of martensite and retained austenite. The type of martensite matrix changed from acicular martensite to lath martensite from the surface to the core. The hardness of the carburized layer gradually decreased as the carbon content decreased. A thermodynamic model was used to show that the low-carbon retained austenite was easier to transform into martensite at lower temperatures, since the high-carbon retained austenite was more thermally stable than the low-carbon retained austenite. The mechanical stability—not the thermal stability—of the retained austenite in the carburized layer dominated after carburizing and quenching, and cryogenic treatment had a limited effect on promoting the martensite formation. During low-temperature tempering, the solid-solution carbon content of the martensite decreased, the compressive stress on the retained austenite was reduced and the mechanical stability of the retained austenite decreased. Therefore, during cooling after low-temperature tempering, the low-carbon retained austenite transformed into martensite, whereas the high-carbon retained austenite still remained in the microstructure. The changes in the martensite matrix hardness had a far greater effect than the transformation of the retained austenite to martensite on the case hardness of the carburized layer.

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Morphology and Formation Mechanism of Martensite in Steels with Different Carbon Content

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.201-203.1612 ◽

2011 ◽

Vol 201-203 ◽

pp. 1612-1618 ◽

Cited By ~ 4

Author(s):

Yun Ping Ji ◽

Zong Chang Liu ◽

Hui Ping Ren

Keyword(s):

Electron Microscope ◽

Carbon Steel ◽

Carbon Content ◽

Formation Mechanism ◽

Lath Martensite ◽

High Carbon Steel ◽

Volumetric Strain ◽

Medium Carbon Steel ◽

Plate Martensite ◽

Low Carbon

0MnVTiNb, 12Cr1MoV, 20Cr2Ni4, 35CrMo, 40Cr, 42CrMo, 60Si2CrV and T8 steels and Fe-1.2C alloy were used to study the morphology and formation mechanism of martensite by metallographic microscope, QUANTA-400 environmental scanning electron microscope and JEM-2100 transmission electron microscope after they were austenized at different temperature and then quenched respectively. The results show that the martensite of low-carbon steel is lath martensite, the martensite of high-carbon steel is plate martensite, and the martensite of medium-carbon steel is the integrated microstructure of lath martensite and plate martensite. With the increase of carbon content, the morphology of martensite in steel evolves from lath shape to plate shape, the distribution of martensite slices changes from in parallel to with crossing angle, and the substructure evolves from high density dislocations and stacking faults to twin crystals. The martensite in steel can nucleate in the austenite crystal grain interior as well as along the austenite crystal grain boundary. It is proposed that the volumetric strain energy in martensite transformation is the essential reason of the different morphologies of martensite.

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Study of the influence of the increased carbon content in electrodes on structure and properties of the welding seam during welding of 110G13 steel

Technology audit and production reserves ◽

10.15587/2706-5448.2021.237358 ◽

2021 ◽

Vol 4 (3(60)) ◽

pp. 14-17

Author(s):

Volodymyr Pashynskyi ◽

Igor Boyko

Keyword(s):

Carbon Steel ◽

Weld Metal ◽

Carbon Content ◽

Weld Pool ◽

High Carbon Steel ◽

Carbon Steels ◽

Structure And Properties ◽

High Carbon ◽

Electrode Coating ◽

Effective Measure

The object of research is the effect of the carbon-forming component of coated electrodes for welding and surfacing of Gadfield steel (110G13L and analogs) on the structure and properties of the weld. One of the most problematic areas in the welding and surfacing of high-carbon steel is the high irregularity of the rod and coating melting rates. Therefore, the non-melted part of the coating is literally poured into the weld pool, which leads to significant chemical and structural inhomogeneity of the welded metal. The main hypothesis of the study is the assumption that it is possible to increase the homogeneity of the deposited metal by changing the conditions for the transition of carbon from the electrode to the weld pool by using an electrode rod made of carbon steel. In the course of the study, electrode rods with different carbon contents were used. With an increase in the carbon content in the composition of the electrode rod, the fluidity of the drops increased, which contributed to a decrease in the strength of the welding current without harm to the welding and technological characteristics. This allows to reduce the generation of heat in the base metal, that is an effective measure to prevent hot cracks in the weld metal and heat affected zone Studies of the composition of the electrode metal droplets and the weld material showed that with an increase in the carbon content in the electrode rod from 0.08 % to 0.8 %, the carbon content in the droplets increases from 0.3 % to 0.97 %. The carbon content in the weld metal is 1.1 %. The assimilation of manganese by a drop increases with an increasing of coating and the droplet interaction time. A significant increasing in the rate of coating melting was obtained. This is due to the fact that the concomitant decrease in the content of graphite in the coating contributes to a decrease in the refractoriness of the electrode coating. The use of high carbon steels for the manufacturing of electrode rods for welding and surfacing of Gadfield steel improves the properties of the welded metal and sanitary and hygienic parameters.

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Effect of Salt Bath Composition on the Chromium Diffusion on Plain Carbon Steels by TRD Process

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.326-328.377 ◽

2012 ◽

Vol 326-328 ◽

pp. 377-382 ◽

Cited By ~ 5

Author(s):

A. Ghadi ◽

Mansour Soltanieh ◽

H.R. Karimi Zarchi

Keyword(s):

Carbon Steel ◽

Carbon Content ◽

Salt Bath ◽

Plain Carbon Steel ◽

Carbon Steels ◽

Reactive Diffusion ◽

Cylindrical Shape ◽

Bath Composition ◽

High Carbon ◽

High Carbon Content

The thermo-reactive diffusion (TRD) process is used for diffusing an element to the metallic steel substrate. TRD is carried out by using either salt bath or fluidized bed methods. In this research, the molten salt bath method is used. Ferro chromium was dissolved in the molten borax as the source of chromium in the salt. Samples of cylindrical shape of plain carbon steel with 10 mm diameter and 20 mm height were treated at 1000°C for 14 hours in different baths including either low carbon ferro chromium (LCFC) or high carbon ferro chromium (HCFC) powder. The purpose of this research is to investigate the effect of the salt bath composition on the diffusion of chromium and formation of chromium compound layer on plain carbon steel by using the salt bath method. The coating thickness layers were measured by SEM. The different phases formed on the samples, due to different amounts of carbon in treating salt bath, were determined by X-ray diffraction. It was found that in molten borax salt with high carbon content (high carbon ferro chromium) very few amount of chromium diffused into the plain carbon steel. The thickness of the diffused chromium layer in low and high carbon content ferro chromium in molten borax, is around 32±8 µm and 6.8±1.2 µm, respectively. A number of tests were conducted to address this effect.

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ALGOMA AR225

Alloy Digest ◽

10.31399/asm.ad.cs0138 ◽

2003 ◽

Vol 52 (12) ◽

Keyword(s):

Carbon Steel ◽

Chemical Analysis ◽

Physical Properties ◽

Carbon Content ◽

Brinell Hardness ◽

Low Cost ◽

Heat Treating ◽

Rolled Plate ◽

High Carbon ◽

High Carbon Content

Abstract Algoma AR225 is a carbon steel developed primarily to supply a low-cost material for high-abrasion applications. It is furnished in the form of as-rolled plate with a relatively high carbon content (0.35-0.45%). AR-225 is sold on the basis of chemical analysis only; the number 225 signifies the approximate Brinell hardness. On thicknesses one-half inch and over, this Brinell value may be lower than 225 because of higher finishing temperatures. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, heat treating, machining, and joining. Filing Code: CS-138. Producer or source: Algoma Steel Corporation Ltd.

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Effect of Soaking Time on Paste Carburizing of Carburized Low Carbon Steel

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.740.93 ◽

2017 ◽

Vol 740 ◽

pp. 93-99

Author(s):

Muhammad Hafizuddin Jumadin ◽

Bulan Abdullah ◽

Muhammad Hussain Ismail ◽

Siti Khadijah Alias ◽

Samsiah Ahmad

Keyword(s):

Carbon Steel ◽

Carbon Content ◽

Low Carbon Steel ◽

Case Depth ◽

Carbon Steels ◽

Low Carbon ◽

Soaking Time ◽

Low Carbon Steels ◽

Carburized Steel ◽

Carburizing Process

Increase of soaking time contributed to the effectiveness of case depth formation, hardness properties and carbon content of carburized steel. This paper investigates the effect of different soaking time (7-9 hours) using powder and paste compound to the carburized steel. Low carbon steels were carburized using powder and paste compound for 7, 8 and 9 hours at temperature 1000°C. The transformation of microstructure and formation carbon rich layer was observed under microscope. The microhardness profiles were analyzed to investigate the length of case depth produced after the carburizing process. The increment of carbon content was considered to find the correlation between types of carburizing compound with time. Results shows that the longer carburized steel was soaked, the higher potential in formation of carbon rich layer, case depth and carbon content, which led to better hardness properties for carburized low carbon steel. Longer soaking time, 9 hours has a higher dispersion of carbon up to 41%-51% compare to 8 hours and 7 hours. By using paste carburizing, it has more potential of carbon atom to merge the microstructure to transform into cementite (1.53 wt% C) compare to powder (0.97 wt% C), which increases the hardness of carburized steel (13% higher).

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Pengaruh Teknik Tempa Lipat Terhadap Perubahan Sifat Mekanik Material AISI O1 Pada Pembuatan Pisau Tanto

Jurnal Rekayasa Energi dan Mekanika ◽

10.26760/jrem.v1i1.51 ◽

2021 ◽

Vol 1 (1) ◽

pp. 51

Author(s):

Alfan Ekajati Latief ◽

Syahril Sayuti ◽

Rakean Wide Windujati

Keyword(s):

Heat Treatment ◽

Carbon Steel ◽

Treatment Process ◽

Lath Martensite ◽

High Carbon Steel ◽

Medium Carbon Steel ◽

Raw Material ◽

High Carbon ◽

Micro Structure ◽

Medium Carbon

ABSTRAKTanto merupakan senjata tajam yang berasal dari Jepang dan merupakan senjata kedua bagi para Samurai di Jepang. Tanto biasa terbuat dari baja karbon menengah hingga baja karbon tinggi yang. Material baja yang digunakan untuk pembuatan Tanto dalam penelitian ini adalah baja AISI seri O1 karena memiliki karakteristik sifat mampu bentuk yang baik serat dapat dikuatkan melalui proses heat treatment. Material baja ini dibuat dengan proses tempa lipat dengan variasi tempa empat lipatan dan satu lipatan. Pembuatan Tanto dan spesimen uji dilakukan dengan proses tempa lipat secara konvensional menggunakan tungku arang, dengan temperatur tempa rata-rata yaitu ±1200oC, kemudian dilanjutkan dengan quenching pada temperatur ± 850oC, serta tempering pada temperatur ±250oC. Penelitian ditujukan untuk mengetahui pengaruh dari proses tempa empat lipatan dan tempa satu lipatan terhadap sifat mekanik, yaitu kekerasan dan kekuatan impak serta untuk melihat perubahan pada struktur mikro. Hasil pengujian menunjukkan bahwa nilai kekerasan paling tinggi sebesar41HRC yang dimiliki oleh pada raw material, ,sedangkan nilai impak paling tinggi sebesar 224,02 Joule/cm² ayng dicapai oleh material dengan proses tempa empat lipatan, Fasa akhir yang ditemukan pada baja tempa empat lipatan adalah bainit dan martensit, sementara perlit dan ferit ditemukan pada baja satu lipatan, dan lath martensit ditemukan pada pada raw material Kata kunci: Pisau Tanto, Tempa lipat ,Quenching, Tempering, Uji Impak ABSTRACT Tanto is a sharp weapon originating from Japan and is the second weapon for Samurai in Japan. Tanto is usually made of medium carbon steel to high carbon steel. The material which is used in this research is AISI O1 series steel because of its high ability to be formed and also can be made tough through a heat treatment process. This steel is made by folding forge process, with variation in number of folding, which is 4 folds and 1 fold. The making of Tanto and test specimens was carried out by conventional fold forging processes by using a charcoal furnace, with an average forging temperature at ± 1200oC, continue with quenching at ± 850oC, and tempering at ± 250oC. The research is carried out in order to determine the effect of the four-folds forging and one-fold forging to the mechanical behavior, which are hardness and impact strength, and also to see change in its micro structure. The test that have been carried out shows that the highest hardness value of 41 HRC owned by raw material, while the highest impact value of 224.02 Joules / cm² obtained by material with four layer forging process. Final phases that found in the four-fold forged steel are bainite and martensite, pearlite and ferrite found in one-fold forged steel. and lath martensite in found in the raw material. Keywords: Tanto Knife, Folding Forging, Quenching, Tempering, Testing, Impact Tests

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Characterization of Microstructure in High-Hardness Surface Layer of Low-Carbon Steel

Metals ◽

10.3390/met10080995 ◽

2020 ◽

Vol 10 (8) ◽

pp. 995

Author(s):

Haitao Xiao ◽

Shaobo Zheng ◽

Yan Xin ◽

Jiali Xu ◽

Ke Han ◽

...

Keyword(s):

Surface Layer ◽

Carbon Steel ◽

Yield Strength ◽

Carbon Content ◽

Acicular Ferrite ◽

Lath Martensite ◽

Low Carbon Steel ◽

Low Carbon ◽

Upper Bainite ◽

Mixed Microstructure

Surface hardening improves the strength of low-carbon steel without interfering with the toughness of its core. In this study, we focused on the microstructure in the surface layer (0–200 μm) of our low-carbon steel, where we discovered an unexpectedly high level of hardness. We confirmed the presence of not only upper bainite and acicular ferrite but also lath martensite in the hard surface layer. In area of 0–50 μm, a mixed microstructure of lath martensite and B1 upper bainite was formed as a result of high cooling rate (about 50–100 K/s). In area of 50–200 μm, a mixed microstructure of acicular ferrite and B2 upper bainite was formed. The average nanohardness of the martensite was as high as 9.87 ± 0.51 GPa, which was equivalent to the level reported for steel with twenty times the carbon content. The ultrafine laths with an average width of 128 nm was considered to be a key cause of high nanohardness. The average nanohardness of the ferrites was much lower than for martensite: 4.18 ± 0.39 GPa for upper bainite and 2.93 ± 0.30 GPa for acicular ferrite. Yield strength, likewise, was much higher for martensite (2378 ± 123 MPa) than for upper bainite (1007 ± 94 MPa) or acicular ferrite (706 ± 72 MPa). The high yield strength value of martensite gave the surface layer an exceptional resistance to abrasion to a degree that would be unachievable without additional heat treatment in other steels with similar carbon content.

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