Wear Resistance under Non-Lubricated Condition of Nb-Containing TWIP Steel

MRS Advances ◽  
2017 ◽  
Vol 2 (61) ◽  
pp. 3765-3771
Author(s):  
V.H. Mercado ◽  
I. Mejía ◽  
Y. Salinas-Escutia ◽  
A. Bedolla-Jacuinde

ABSTRACTTwinning induced plasticity (TWIP) steels are one of the most attractive advanced high-strength steels for structural applications due to their unique combination of strength and ductility, which is associated with so-called “mechanical twinning”, where twins act as strong obstacles to the dislocation motion. In this context, Nb addition to TWIP steel increases the strength and refines grain size by nanoscale NbC precipitates. Nowadays, high-manganese TWIP steels are extensively studied. However, information in the specialized literature about their tribological properties is limited. This research work studies the wear behavior of high-manganese austenitic Fe–20Mn–1.5Si–1.5Al–0.4C TWIP steel microalloyed with Nb. The wear behavior was evaluated under non-lubricated sliding condition using the “pin-on-ring” technique. As-solution heat treated samples were worn under loads of 53, 104 and 154 N, and at sliding speeds of 0.22, 0.60 and 0.87 m/s. The wear resistance was evaluated in terms of the loss weight. Wear debris and worn surfaces were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). In general, results show that the wear resistance significantly improves as the sliding speed increases. On the other hand, Nb addition to present TWIP steel produces a slight increase of the wear resistance. Also, it was found that the oxide layer plays a significant role in the wear resistance behavior of this kind of steel.

2015 ◽  
Vol 1765 ◽  
pp. 59-64 ◽  
Author(s):  
V.H. Mercado ◽  
I. Mejía ◽  
A. Bedolla-Jacuinde

ABSTRACTHigh-Mn austenitic twinning induced plasticity (TWIP) steels are the object of intense worldwide scientific study due to the promising combination of strength and ductility of these alloys. Mechanical behavior of this family of new generation steels has been extensively studied recently. However, limited information regarding their tribological properties is available in the literature. The aim of this research work is to study the wear behavior of a high-Mn austenitic Fe–20Mn–1.5Si–1.5Al–0.4C TWIP steel microalloyed with Ti. The wear behavior was evaluated under dry sliding condition by the ‘‘pin-on-ring’’ method. For this purpose, solution-treated samples were worn for 10 km against a counterface disc made of hardened AISI M2 steel, under loads of 52, 103 and 154 N, and at speeds of 0.20, 0.60 and 0.86 m/s. The wear resistance was evaluated from the average wear rate. Wear debris and worn surfaces were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (SEM-EDS). The Ti addition to TWIP steel slightly improved the wear resistance particularly at a speed of 0.86 m/s and at loads of 52 and 103 N. Results show that the wear resistance increases with increasing sliding speed. This is attributed to the formation of an oxide layer acting as a protective layer against wear, which suggests that the main wear mechanism for the studied TWIP steel under these conditions is oxidative.


2016 ◽  
Vol 1812 ◽  
pp. 35-40 ◽  
Author(s):  
Humberto Hernández-Belmontes ◽  
Ignacio Mejía ◽  
Cuauhtémoc Maldonado

ABSTRACTHigh-Mn Twinning-Induced Plasticity (TWIP) steels are advanced high-strength steels (AHSS) currently under development; they are fully austenitic and characterized by twinning as the predominant strengthening mechanism. TWIP steels have high strength and formability with an elongation up to 80%, which allows reduction in automotive components weight and fuel consumption. Since the targeted application field of TWIP steels is the automotive industry, steels need high mechanical performance with good weldability and excellent corrosion resistance. However, there is lack of information about the weldability behavior of these advanced steels. This research work aims to study the weldability of a new generation of high-Mn austenitic TWIP steels microalloyed with B. Weldability was examined using spot welds produced by Gas Tungsten Arc Welding. Microstructural changes were examined using light optical metallography. Segregation of elements in the weld joint was evaluated using point and elemental mapping chemical analysis by Scanning Electron Microscopy and Electron-Dispersive Spectroscopy; while the hardness properties were examined with Vickers microhardness testing (HV25). Experimental results show that the welded joint microstructure consists of austenitic dendritic grains in the fusion zone, and equiaxed grains in the heat affected zone. Notably, the boron microalloyed TWIP steel exhibited poor weldability, showing hot cracking. Additionally, the studied TWIP steels showed a high degree of segregation in the fusion zone; Mn and Si segregated into the interdendritic regions, while Al and C preferentially segregated in dendritic areas. Finally, the welded joints of the TWIP steels showed microhardness values lower than the base material. In general, the present TWIP steels have problems of weldability, which are corroborated with microstructural changes, elements segregation and microhardness loss.


MRS Advances ◽  
2018 ◽  
Vol 3 (64) ◽  
pp. 3949-3956
Author(s):  
H. Hernández-Belmontes ◽  
I. Mejía ◽  
V. García-García ◽  
C. Maldonado

ABSTRACTHigh-Mn Twinning Induced Plasticity (TWIP) steels are an excellent alternative in the design of structural components for the automotive industry. The TWIP steels application allows weight reduction, maintaining the performance of vehicles. Nowadays the research works focused on TWIP steel weldability are relative scarce. It is well-known that weldability is one of the main limitations for industrial application of TWIP steel. The main goal of this research work was studied the effect of heat input on the microstructural changes generated in a TWIP steel microalloyed with Ti. A pair of welds were performed through Gas Tungsten Arc Welding (GTAW) process. The GTAW process was carried out without filler material, using Direc Current Electrode Negative (DCEN), tungsten electrode EWTh-2 and Ar as shielding gas. The microstructure and average grain size in the fusion (FZ) and heat affected zone (HAZ) were determined by light optical metallography (LOM). Elements segregation in the FZ was evaluated using point and elemental mapping chemical analysis (EPMA) by Scanning Electron Microscopy and Electron Dispersive Spectroscopy (SEM-EDS). Phase transformations were evaluated using X-ray diffraction (XRD). Finally, the hardness were measured by means of Vickers microhardness testing (HV500). The results show that the FZ is characterized by a dendritic solidification pattern. Meanwhile, the HAZ presented equiaxed grains in both weld joints. On the other hand, the TWIP-Ti steel weldments did not present austenite phase transformations. Nevertheless, the FZ exhibited variations in the chemical elements distribution (Mn, Al, Si and C), which were higher as the heat input increases. Finally, the heat input reduced the microhardness of TWIP-Ti steel weld joints. Although post-welding hardness recovery was detected, which is associated with precipitation of Ti second-phase particles.


2016 ◽  
Vol 850 ◽  
pp. 197-201
Author(s):  
Chao Zhi ◽  
Yi Fei Gong ◽  
Ai Min Zhao ◽  
Jian Guo He ◽  
Ran Ding

The wear performance and wear mechanism under two-body abrasion of five advanced high strength steels, i.e. Nanobainite (NB) steel, Tempered Martensitic (TM) steel, Dual Phase (DP) steel, Transformation Induced Plasticity (TRIP) Steel and Twining Induced Plasticity (TWIP) steel were studied. By using the scanning electron microscopy (SEM), we investigated the wearing surface. Phase transformation strengthening behavior was also be discussed by analyzing the surface and sub-surface after abrasion. The results showed that micro-cutting was the major role of wear mode in the condition of two-body abrasion. In the circumstance of two-body abrasion, hardness was an important factor, the property of wear resistance enhanced while the hardness increased except for TM steel. NB steel possessed the best wear resistance which was 1.71 times higher than that of TWIP steel. The retained austenite transformed into martensite which can improve the hardness so that it enhanced the wear resistance of NB steel.


2015 ◽  
Vol 651-653 ◽  
pp. 539-544 ◽  
Author(s):  
Andrea Erhart ◽  
André Haufe ◽  
Alexander Butz ◽  
Maksim Zapara ◽  
Dirk Helm

High manganese content TWinning Induced Plasticity (TWIP) steels are promising for the production of lightweight components due to their high strength combined with extreme ductility, see [1]. This paper deals with the implementation of a constitutive model for the macroscopic deformation behavior of TWIP steels under mechanical loading with the aim of simulating metal forming processes and representing the behavior of TWIP-steel components – for example under crash loading - with the Finite Element code LS-DYNA®and refers to our recently published papers: [2],[4],[5]. Within the present paper we focus on the implementation of the model formulated in [2] and its extension to stress dependent twinning effects.


2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Jian Wang ◽  
Qingliang Wang ◽  
Xiao Zhang ◽  
Dekun Zhang

The coupled impact and rolling wear behavior of the medium-manganese austenitic steel (Mn8) were studied by comparison with the traditional Hadfield (Mn13) steel. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), and transmission electron microscope (TEM) were used to analyze the wear and hardening mechanisms. The experimental results show that the impact and rolling wear resistance of hot-rolled medium-manganese steel (Mn8) is better than that of high-manganese steel (Mn13) under conditions of low-impact load. The better work hardening sensitivity effectively improves the wear resistance of medium-manganese steel. Not only the coefficient of friction is low, but the mass loss and wear rate of the wear are lower than that of high-manganese steel. After impact and rolling wear, a hardened layer with a thickness of about 600 μm is formed on the wear surface. The highest microhardness of the subsurface layer for Mn8 is about 594 HV and the corresponding Rockwell hardness is about 55 HRC, showing the remarkable work hardening effect. The wear-resistant strengthening mechanism of medium-manganese steel is compound strengthening, including the deformation-induced martensitic transformation, dislocation strengthening, and twin strengthening. In initial stages of impact and rolling abrasion, dislocation strengthening plays a major role. When the deformation reaches a certain extent, the deformation-induced martensitic transformation and twinning strengthening begin to play a leading role.


2011 ◽  
Vol 148-149 ◽  
pp. 1085-1088
Author(s):  
Gholam Reza Razavi

TWIP steels are high manganese steel (Mn: 17% - 35%) which are used for shaping car bodies. The structure of this kind of steels remains austenite even in room temperature. Due to low SFE (Stacking Fault Energy) twinning of grains is governing reformation mechanism in this kind of steels which strengthen TWIP steel. Regarding heat treatment influences on mechanical properties of TWIP steels, in this paper we discuss twinning phenomenon resulting from this kind of treatment. For this, following casting and hot rolling processes, we anneal the steel at 1100°C and different time cycles and study its microstructure using light microscope. The results showed that with decreasing grain size the number of twin annealing added And four types of annealing twin in the microstructure, in the end they all become one twin and then turn into grain.


2016 ◽  
Vol 1812 ◽  
pp. 123-128 ◽  
Author(s):  
Antonio E. Salas-Reyes ◽  
Ignacio Mejía ◽  
José M. Cabrera

ABSTRACTIt is well-known that metal and alloys develop internal cavities when subjected to uniaxial or multiaxial tensile strains at elevated temperature. In most cases, cavitation may lead to premature failure during forming. Therefore, damage and fracture behavior imposes significant limitations in hot metal-forming processes. Although high-Mn austenitic TWIP steels exhibit a unique combination of strength and ductility, cavitation during hot working is one issue that must be tackled. The aim of this research work is to determine the effect of Ti microaddition on cavity mechanisms of Fe-22Mn-1.5Al-1.3Si-0.5C TWIP steel under uniaxial hot-tensile condition at 800 °C and constant true strain rate of 10-3 s-1. For this purpose, light optical (LOM) and scanning electron (SEM) microscopies and image analysis were applied to quantify cavities formation along longitudinal section of deformed samples near to the fracture surface. The number of cavities greater than 10 µm (critical length) in non-microalloyed and Ti microalloyed TWIP steels were 2.75 and 3.75 cavities/mm2, respectively. On the other hand, average cavity area was 125 and 152 µm2, respectively. Both TWIP steels showed cavities type “r”, “l” and “A”. Finally, Ti microaddition to TWIP steel resulted in a predominant brittle fracture behavior due to finer grain-boundary precipitation, which weakens grains cohesion and accelerates crack growth by grain-boundary sliding. In this case, crack growth behavior is explained in terms of a void interconnection mechanism.


2006 ◽  
Vol 15-17 ◽  
pp. 852-857 ◽  
Author(s):  
Mathieu Iker ◽  
D. Gaude-Fugarolas ◽  
Pascal J. Jacques ◽  
Francis Delannay

Twinning-Induced Plasticity steels (TWIP steels) are extensively studied due to their ultra-high strain-hardening rate, that brings about a remarkable combination of ductility and strength. Twinning can be observed in high manganese-carbon steels. This paper considers hardening by combination of mechanical twinning with carbide precipitation. The kinetics of precipitation and the morphological evolution of carbides with annealing time were studied for two different TWIP steels with high manganese and carbon contents. The steels are first cold-rolled and then annealed at 800°C for recrystallization and carbide precipitation. Depending on the steel composition, the kinetics of precipitation and the morphology of the carbides are quite different. The influence of the annealing cycle on the mechanical properties has also been assessed. The results are used to discuss the influence of composition, stacking fault energy (SFE) and carbide precipitation on twinning. We show that the usual criteria based on the SFE only are not sufficient to characterize the twinning ability of a steel.


MRS Advances ◽  
2017 ◽  
Vol 2 (61) ◽  
pp. 3797-3803
Author(s):  
A.E. Salas-Reyes ◽  
I. Mejía ◽  
J.M. Cabrera

ABSTRACTAdvanced high-strength steels as Twinning Induced Plasticity (TWIP) steels have been developed using microalloying elements and subsequent thermo-mechanical processing techniques. Moreover, under hot-working conditions, these steels undergo significant microstructural changes as a result of preferred crystallographic orientation (texture) of grains. In order to evaluate this behavior, one non-microalloyed and other single Nb-microalloyed TWIP steels were melted in an induction furnace and cast into metal and sand molds. Samples with austenitic grain sizes between 400 and 2000 µm were deformed at 800 °C and strained at a constant strain rate of 10-3 s-1, and deformation state was examined by means of electron backscatter diffraction (EBSD) technique near to the fracture tip. It was found that non-microalloyed TWIP steel solidified in both metal and sand mold exhibits dynamically recrystallized grains. On the other hand, Nb microaddition has a strong influence in TWIP steel retarding the onset of recrystallization kinetics, showing low angle sub-structured grains. Furthermore, it was possible identifying the crystallographic orientation of grains using the inverse pole figures (IPF) and the orientation distribution function (ODF). Weak cube {001}<100> recrystallization and E{111}<110> γ-fiber deformation textures components were detected.


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