The significance of microstructural evolution on governing impact toughness of Fe-0.2C-6Mn-3Al medium-Mn TRIP steel studied by a novel heat treatment

Author(s):  
Zhichao Li ◽  
Xinjing Li ◽  
Yanjie Mou ◽  
Zhihui Cai ◽  
Devesh Misra ◽  
...  

Abstract We address here the continuing challenge and scientific gap in obtaining high impact toughness in medium-Mn steels. While addressing the challenge, the objective of the study described here is to obtain a fundamental understanding via critical experimental analysis of the reasons underlying high impact toughness that was successfully obtained in Fe-0.2C-6Mn-3Al medium-Mn TRIP steel. Electron microscopy and X-ray diffraction studies clearly underscored the absence of the TRIP effect in Fe-0.2C-6Mn-3Al medium manganese steel during impact and the volume fraction of austenite played a determining role in governing impact toughness. The highest impact toughness of 213.6 J · cm–2 was obtained when the steel was subjected to an intercritical hardening temperature of 700 °C and low tempering temperature of 200 °C. The presence of martensite in the microstructure reduced the impact toughness on quenching from 750 – 850 °C.

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 507 ◽  
Author(s):  
Luca Pezzato ◽  
Claudio Gennari ◽  
Dmitry Chukin ◽  
Michele Toldo ◽  
Federico Sella ◽  
...  

During the production of forged metal components, the sequence of heat treatments that are carried out, as well as hot working, remarkably influences mechanical properties of the product, in particular impact toughness. It is possible to tailor impact toughness by varying tempering temperature and soaking time after hardening treatment, widening the application range of structural steels. In this work, we consider the effects of a second tempering treatment on the microstructural properties and impact toughness of a structural steel EN 10025-6 S690 (DIN StE690, W. n: 1.8931). The steel was first forged and quenched in water after austenitization at 890 °C for 4 h. After quenching different tempering treatments were performed, at 590 °C in single or multiple steps. The effect of these treatments was evaluated both in microstructural terms, by means of optical microscopy, scanning and transmission electron microscopy and X-ray diffraction, and in terms of impact toughness. The mechanical behavior was correlated with the microstructure and a remarkable increase in impact toughness was found after the second tempering treatment due to carbide shape change.


2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Alfan Ekajati Latief ◽  
Nuha Desi Anggraeni ◽  
Dedy Hernady

ABSTRAK Serat alam yang berfungsi sebagai penguat memiliki sifat yang lebih ringan, mudah dibentuk, tahan korosi, harga murah dan memiliki kekuatan yang sama dengan material logam. Serat bahan alami yang memiliki kekuatan tarik, tekan dan impak yang baik diantaranya serat rami dan daun nanas. Untuk matriks Polipropilena high impact (PPHI) yang banyak digunakan dalam industri otomotif.. Pada penelitian ini dipelajari pengaruh fraksi volume serat alami terhadap sifat mekanik komposit PPHI berpenguat serat alami. Komposit PPHI dibuat dengan menggunakan metode Hand Lay Up pada temperatur 2500C dengan fraksi volume serat alami sebesar 10%, dimana serat dibuat digunting halus hingga memiliki ukuran mesh 120/170, 170/200 dan dibawah 200 mesh, Kekuatan tarik komposit diukur dengan mengacu pada standar ASTM 3039, kekuatan tekan diukur mengacu pada ASTM D 695. Harga Impak dari komposit diukur dengan mengacu pada ASTM D 6110-04. Pada penelitian ini dapat disimpulkan, fraksi volume 10 % serat alami yang baik ketika dicampur dengan matriks polipropilena high impact adalah serat nanas dengan meshing 170/200 dapat meningkatkan kekuatan tarik PPHI sebesar 40 % dan meningkatkan harga impak PPHI sebesar 50,8 % jika dilihat penelitan sebelumnya yakni menggunakan serat rami dibawah mesh 1200 dengan matriks PPHI. Kata Kunci: Rami, Daun Nanas, Polipropilena High Impact, Hand Lay Up. ABSTRACT Natural fibers that function as reinforcement have lighter properties, are easily formed, are corrosion resistant, are cheap and have the same strength as metal materials. Natural fiber which has good tensile, compressive and impact strength including Ramie and pineapple leaves. For high impact polypropylene matrix (PPHI) which is widely used in the automotive industry. In this study the effect of volume fraction of natural fibers on the mechanical properties of PPHI composites with natural fiber reinforced properties was studied. PPHI composites are made using the Hand Lay Up method at a temperature of 2500C with a volume fraction of natural fibers of 10%, where fibers are made finely shaved to have a mesh size of 120/170, 170/200 and below 200 mesh, the tensile strength of the composite is measured by reference to the standard ASTM 3039, compressive strength measured refers to ASTM D 695. The impact price of the composite is measured with reference to ASTM D 6110-04. In this study it can be concluded, a good volume fraction of 10% natural fiber when mixed with high impact polypropylene matrix is pineapple fiber with meshing 170/200 can increase the tensile strength of PPHI by 40% and increase the impact price of PPHI by 50.8% if seen by research previously that used hemp fiber under mesh 1200 with PPHI matrix. Keywords: Ramie Pineapple, High Impact Polypropylene, Hand Lay Up.


2017 ◽  
Vol 898 ◽  
pp. 1468-1477 ◽  
Author(s):  
Hong Wei Li ◽  
Guo Ping Li ◽  
Wen Chen ◽  
Li Hui Sun ◽  
Feng Hua Luo ◽  
...  

TiC base high manganese steel-bonded carbide was manufactured with conventional powder metallurgy method to service in wear and impact resistant condition. WC was added in the alloy in the form of (W,Ti)C carbides to improve the impact toughness and expand the applications of alloy, meanwhile, cobalt powder was also used to enhance the wettability of the metallic binder on the ceramic phase. Results showed that the impact toughness of the alloy was increased remarkably with the increase of WC content. The impact toughness reached 10.6 J/cm2 when WC content was 10.5 wt.%, while the hardness of the alloy did not decrease. It was indicated that the appropriate content of WC and cobalt can improve impact toughness and wear resistance of the alloy greatly with little increase in the production cost.


2020 ◽  
Vol 835 ◽  
pp. 163-170
Author(s):  
Hayam A. Aly ◽  
Adel Nofal ◽  
Abdel Hamid A. Hussein ◽  
Elsayed M. El-Banna

This study aimed at optimizing impact toughness and high wear resistant carbidic austempered ductile iron (CADI) by controlling the morphology, size and quantity of carbides. The effects of dynamic solidification, niobium addition, combined action of them and heat treatment have been investigated. Investigations were performed by means of the image analyzer, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and X-ray diffraction. Impact toughness, hardness and abrasion wear resistance tests were conducted. Fracture surfaces were studied. Results indicated that microstructural control during solidification is the most valuable tool to attain the optimum combination between impact toughness and wear resistance in CADI. Combined action of Nb addition and dynamic solidification improves impact toughness, hardness and wear resistance even more than the action of each individual factor. In the as-cast condition, impact toughness, hardness and abrasion resistance were improved after dynamic solidification compared to statically solidify one by 31.2%, 18.75% and 87.96% respectively. This enhancement was increased to 36.9%, 25.93% and 128. % by adding 1% Nb. Lower tempering temperature of 275°C exhibit best hardness and abrasion resistance better than higher tempering temperature of 375°C.


2019 ◽  
Vol 9 (20) ◽  
pp. 4231
Author(s):  
Oskari Haiko ◽  
Antti Kaijalainen ◽  
Sakari Pallaspuro ◽  
Jaakko Hannula ◽  
David Porter ◽  
...  

In this paper, the effects of different tempering temperatures on a recently developed ultrahigh-strength steel with 0.4 wt.% carbon content were studied. The steel is designed to be used in press-hardening for different wear applications, which require high surface hardness (650 HV/58 HRC). Hot-rolled steel sheet from a hot strip mill was austenitized, water quenched and subjected to 2-h tempering at different temperatures ranging from 150 °C to 400 °C. Mechanical properties, microstructure, dislocation densities, and fracture surfaces of the steels were characterized. Tensile strength greater than 2200 MPa and hardness above 650 HV/58 HRC were measured for the as-quenched variant. Tempering decreased the tensile strength and hardness, but yield strength increased with low-temperature tempering (150 °C and 200 °C). Charpy-V impact toughness improved with low-temperature tempering, but tempered martensite embrittlement at 300 °C and 400 °C decreased the impact toughness at −40 °C. Dislocation densities as estimated using X-ray diffraction showed a linear decrease with increasing tempering temperature. Retained austenite was present in the water quenched and low-temperature tempered samples, but no retained austenite was found in samples subjected to tempering at 300 °C or higher. The substantial changes in the microstructure of the steels caused by the tempering are discussed.


Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 45 ◽  
Author(s):  
Erding Wen ◽  
Renbo Song ◽  
Wenming Xiong

The microstructure and wear behavior of a 500 Brinell hardness (HB) grade wear-resistant steel tempered at different temperatures were investigated in this study. The tempering microstructures and wear surface morphologies were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The relationship between mechanical properties and wear resistance was analyzed. The microstructure of the steel mainly consisted of tempered martensite and ferrite. Tempered troosite was obtained when the tempering temperature was over 280 °C. The hardness decreased constantly with the increase of tempering temperature. The same hardness was obtained when tempered at 260 °C and 300 °C, due to the interaction of Fe3C carbides and dislocations. The impact toughness increased first and reached a peak value when tempered at 260 °C. As the tempering temperature was over 260 °C, carbide precipitation would occur along the grain boundaries, which led to temper embrittlement. The best wear resistance was obtained when tempered at 200 °C. At the initiation of the wear test, surface hardness was considered to be the dominant influencing factor on wear resistance. The effect of surface hardness improvement on wear resistance was far greater than the impact toughness. With the wear time extending, the crushed quartz sand particles and the cut-down burs would be new abrasive particles which would cause further wear. Otherwise, the increasing contact temperature would soften the matrix and the adhesive wear turned out to be the dominant wear mechanism, which would result in severe wear.


2013 ◽  
Vol 791-793 ◽  
pp. 440-443
Author(s):  
Hong Bo Li ◽  
Jing Wang ◽  
Han Chi Cheng ◽  
Chun Jie Li ◽  
Xing Jun Su

This paper mainly studied the high temperature quenching oil quenching, tempering temperature on the influence of high strength steel mechanical properties of wear resistant. The results show that high strength and toughness wear-resistant cast steel with 880°C× 30min after oil quenching, the hardness of 38.6HRC steel, the impact toughness value reaches 40.18J/cm2. After 200°C, 400°C and 600°C tempering, with the increase of the tempering temperature, the hardness decreased linearly, as by 600°C tempering, the hardness has been reduced to 22.3HRC. Impact toughness with the tempering temperature, the overall upward trend, the impact toughness of some reduced at 400°C, the highest impact toughness value reaches 113.34J/cm2. From the fracture morphology can be seen, with the increase of tempering temperature, ductile fracture increased, by 600°C tempering is dimple fracture, obviously can not see the traces of brittle fracture.


2010 ◽  
Vol 150-151 ◽  
pp. 779-782
Author(s):  
Qing Xin Zhao ◽  
Zhao Yang Liu ◽  
Jin Rui Zhang ◽  
Ran Ran Zhao

By means of the three-point bending impact equipment, with the measurement of ultrasonic velocity, the impact behavior and damage evolution of reactive powder concrete (RPC) with 0, 1%, 2% and 3% volume fraction of steel fiber were tested. The results showed that steel fiber significantly improved the compressive strength, flexural strength, flexural toughness and impact toughness of RPC matrix. The compressive strength, flexural strength, flexural toughness of RPC with 3% steel fiber increased by 40.1%, 102.1%, and 37.4 times than that of plain concrete, respectively, and simultaneously, the impact toughness of RPC with 3% steel fiber was 93.2 times higher than that with 1% steel fiber. RPC with 2% and 3% steel fiber dosage both had relatively high compressive strength, flexural strength and flexural toughness; however, compared with the sample with 2% steel fiber dosage, the impact toughness of RPC with 3% steel fiber dosage increased by more than 10 times. Therefore, taking economy and applicability into consideration, if we mainly emphasis on the compressive strength, flexural strength and flexural toughness, RPC with 2% steel fiber is optimal. While if impact toughness is critical, RPC with 3% steel fiber would be the best choice.


2012 ◽  
Vol 48 (10) ◽  
pp. 1186 ◽  
Author(s):  
Jundan CHEN ◽  
Wenlin MO ◽  
Pei WANG ◽  
Shanping LU

2011 ◽  
Vol 291-294 ◽  
pp. 1389-1392
Author(s):  
Yan Pei Song ◽  
Hui Gai Wang ◽  
Zhi Ming Feng ◽  
Zhen Kai Zhao

The scrap WCP/Fe-C composites were re-melted in a 50 kg medium frequency induction furnace. A regenerated composites ring was manufactured by centrifugal casting process. The microstructure and properties of the composites before and after re-melting were investigated by SEM with energy dispersive spectroscopy and X-ray diffraction. The results showed that the microstructure of the composites after re-melting was composed of un-dissolved WCP, bainite, bone-like crystallites and graphite. The un-dissolved WCPwere uniformly distributed in the outer region of the regenerated composites ring, their volume fraction attained to about 65 vol. %, and size of the un-dissolved WCPwas obviously smaller than that of the WCPbefore re-melting. The impact toughness of the regenerated composites was below those of the composites before re-melting, the hardness and wear resistance of the regenerated composites were almost same as those of the composites before re-melting under the same test conditions.


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