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

2011 ◽  
Vol 201-203 ◽  
pp. 1612-1618 ◽  
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.

Investigation of Three-Dimensional Geometry of Butterfly Martensite and Analysis of Relationship between Hardness of Lath/Butterfly Two-Phase Martensite and its Grain Thickness in Medium-Carbon Steel

2021 ◽  
Vol 1016 ◽  
pp. 1039-1044
Author(s):  
Takayoshi Niho ◽  
Keisuke Nagato ◽  
Masayuki Nakao
Keyword(s):  
Carbon Steel ◽  
Ion Beam ◽  
Lath Martensite ◽  
High Carbon Steel ◽  
Three Dimensional ◽  
Medium Carbon Steel ◽  
Thin Plates ◽  
Low Carbon ◽  
Two Phase ◽  
Medium Carbon

Medium-carbon steel with approximately 0.6 wt% carbon is widely used for mechanical applications, because the martensite contained in it is harder than that of low-carbon and high-carbon steel. The microstructure of steel martensite varies depending on the carbon content, and the microstructure of medium-carbon steel martensite are a mixture of lath martensite (LM) and butterfly martensite (BM). The geometry of LM grains are thin plates having thicknesses of 0.2–0.5 μm. As for BM, some researches demonstrated that the region of martensite spreads in the depth direction of the observation surface. However, the three-dimensional geometry of BM grains remains unclear. Through cross-sectional observation using focused ion beam (FIB), the present study demonstrates that one BM grain is formed via collision of two plates. Previous research shows that the hardness of LM is inversely correlated with the thickness of the grains. The FIB observation result indicates that geometry of LM and BM grains are both plate-like. In the present study, whether the same relationship is valid for the mixture of LM and BM grains is investigated. The results show that the hardness of medium-carbon steel martensite increases according to the decrease in thickness of constituent grains of the two-phase structure of LM and BM.

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

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

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

Metals ◽  
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.

Application of Rietveld Refinement and Williamson Hall Analysis in Ultra-Low Carbon to High Carbon Steels

2019 ◽  
Vol 969 ◽  
pp. 3-8
Author(s):  
Soumya Sourav Sarangi ◽  
Avala Lavakumar
Keyword(s):  
Carbon Steel ◽  
Dislocation Density ◽  
Rietveld Refinement ◽  
Carbon Concentration ◽  
High Carbon Steel ◽  
Low Carbon Steel ◽  
Lattice Parameter ◽  
Medium Carbon Steel ◽  
Low Carbon ◽  
High Carbon

Current study deals with the microstructural characterization of five different plates of steel with carbon concentration ranging from ultra-low to moderately high. Phase analysis was carried out using XRD technique. The XRD results were analyzed through Rietveld refinement and Williamson Hall plots. Rietveld refinement was carried out to understand the effect of carbon concentration on the lattice parameters of the above steel samples in as-received condition and also after deformation under uni-axial tensile loading. Lattice parameters obtained from refinement showed the strong dependence on carbon concentration of the given steels. But the failed specimens showed somewhat complex results as Spheroidized high carbon steel, Low carbon steel and IF steel showed an increase in lattice parameter whereas Medium carbon steel and Microalloyed steel showed a contraction in lattice parameter. Williamson Hall plot gave the crystallite size, microstrain and dislocation density in the steels. For IF and Microalloyed steels the dislocation density in the material is found to be higher after deformation whereas dislocation density decreased in Spheroidized high carbon steel, Medium carbon steel and Low carbon steel.

Optimum Carbon Content for Tempered Martensitic Steels

1968 ◽  
Vol 90 (1) ◽  
pp. 1-7 ◽  
Author(s):  
J. D. Lubahn ◽  
H. P. Chu
Keyword(s):  
Carbon Steel ◽  
Carbon Content ◽  
High Carbon Steel ◽  
Low Carbon Steel ◽  
Tensile Tests ◽  
Notch Toughness ◽  
Low Carbon ◽  
Martensitic Steels ◽  
High Carbon ◽  
Engineering Concept

Notch-tensile tests were conducted on four quenched and tempered steels to study the effect of carbon content on notch toughness. The toughness was found to decrease when the carbon content was either above or below an optimum value of about 0.35 to 0.40 percent. The general engineering concept which prefers a low-carbon steel to a high-carbon steel for better toughness is briefly discussed in view of the present and previous experimental results.

Investigation of Lath and Plate Martensite in a Carbon Steel

2011 ◽  
Vol 172-174 ◽  
pp. 61-66 ◽  
Author(s):  
Albin Stormvinter ◽  
Annika Borgenstam ◽  
Peter Hedström
Keyword(s):  
Carbon Steel ◽  
Carbon Content ◽  
Morphological Change ◽  
Retained Austenite ◽  
Alloy Composition ◽  
Lath Martensite ◽  
Carbon Steels ◽  
Plate Martensite ◽  
High Carbon ◽  
Martensite Microstructure

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.

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

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).

scholarly journals Laser Welding Dissimilar High-Strength Steel Alloys with Complex Geometries

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 792 ◽  
Author(s):  
Panos Efthymiadis ◽  
Khalid Nor
Keyword(s):  
Carbon Steel ◽  
Laser Welding ◽  
Cross Sections ◽  
High Carbon Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
High Carbon ◽  
Material Chemistry ◽  
Metallurgical Defects

Laser welding of dissimilar high-strength steels was performed in this study for two different geometries, flat and circular samples with material thicknesses of 5 and 8 mm. The material combinations were a low carbon to a medium or high carbon steel. Three different welding systems were employed: a Nd:YAG, a CO2 and a fiber laser. The process stability was evaluated for all the experiments. The resulting full penetration welds were inspected for their surface quality at the top and bottom of the specimens. Cross sections were taken to investigate the resulting microstructures and the metallurgical defects of the welds, such as cracks and pores. Significant hardening occurred in the weld region and the highest hardness values occurred in the Heat Affected Zone (HAZ) of the high carbon steel. The occurrence of weld defects depends strongly on the component geometry. The resulting microstructures within the weld were also predicted using neural network-simulated Continuous Cooling Transformation (CCT) diagrams and predicted the occurrence of a mixture of microstructures, such as bainite, martensite and pearlite, depending on the material chemistry. The thermal fields were measured with thermocouples and revealed the strong influence of component geometry on the cooling rate which in term defines the microstructures forming in the weld and the occurring hardness.

scholarly journals Microstructure and Properties of Heat Affected Zone in High-Carbon Steel after Welding with Fast Cooling in Water

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5059
Author(s):  
Michail Nikolaevich Brykov ◽  
Ivan Petryshynets ◽  
Miroslav Džupon ◽  
Yuriy Anatolievich Kalinin ◽  
Vasily Georgievich Efremenko ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
High Carbon Steel ◽  
Low Carbon Steel ◽  
Tensile Tests ◽  
Low Carbon ◽  
High Carbon ◽  
Mechanical Wear ◽  
Fast Cooling

The purpose of the research was to obtain an arc welded joint of a preliminary quenched high-carbon wear resistant steel without losing the structure that is previously obtained by heat treatment. 120Mn3Si2 steel was chosen for experiments due to its good resistance to mechanical wear. The fast cooling of welding joints in water was carried out right after welding. The major conclusion is that the soft austenitic layer appears in the vicinity of the fusion line as a result of the fast cooling of the welding joint. The microstructure of the heat affected zone of quenched 120Mn3Si2 steel after welding with rapid cooling in water consists of several subzones. The first one is a purely austenitic subzone, followed by austenite + martensite microstructure, and finally, an almost fully martensitic subzone. The rest of the heat affected zone is tempered material that is heated during welding below A1 critical temperature. ISO 4136 tensile tests were carried out for the welded joints of 120Mn3Si2 steel and 09Mn2Si low carbon steel (ASTM A516, DIN13Mn6 equivalent) after welding with fast cooling in water. The tests showed that welded joints are stronger than the quenched 120Mn3Si2 steel itself. The results of work can be used in industries where the severe mechanical wear of machine parts is a challenge.

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