scholarly journals Microstructure and Mechanical Properties of an Austenitic CrMnNiMoN Spring Steel Strip with a Reduced Ni Content

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 392
Author(s):  
Christina Schröder ◽  
Marco Wendler ◽  
Olena Volkova ◽  
Andreas Weiß

The article presents the mechanical properties of the austenitic stainless steel X5CrMnNiMoN16-4-4 after deformation by cold rolling and subsequent short-term tempering (deformation and partitioning (D&P) treatment). Tensile strengths of 1700–900 MPa and beyond were achieved both after work hardening and in the D&P-treated strip. The initial state of austenite in terms of grain size and pre-strengthening, as well as the selected cold rolling temperature significantly influenced the deformation-induced formation of α’ martensite and thus the flow and hardening behavior of the steel. The usage of two different rolling temperature regimes showed that the strength properties in the cold strip can be specifically adjusted. Lower deformation-induced martensite fractions enabled a larger thickness reduction of the strip without increasing the rolling force, while high deformation-induced martensite fractions led to strong hardening at low deformation levels. The D&P-treatment permits the strength of the cold-rolled strip with a predominantly austenitic microstructure to be increased to the required level. The total elongation of such a D&P strip was well over 2%. The D&P treatment of the spring steel strip is a cost-effective alternative to conventional tempering treatment.

2011 ◽  
Vol 176 ◽  
pp. 21-28 ◽  
Author(s):  
Kinga Rodak ◽  
Krzysztof Radwański ◽  
Rafal M. Molak

. In this study, commercial Al was subjected to plastic deformation by multi-axial compression. The microstructure and mechanical properties in dependence on effective strain were studied. Aluminum was processed to effective strain f = 9.6. The misorientation distribution and subgrain/grain size were analyzed by using a scanning electron microscopy (SEM) equipment with electron back scattered diffraction (EBSD) facility. The dislocation microstructure was investigated by a scanning transmission electron microscope (STEM). The mechanical properties as: yield strength (YS), ultimate tensile strength (UTS), uniform and total elongation were performed on MTS QTest/10 machine equipped with digital image correlation method (DIC). Deformation of Al by the multi-axial compression leads to grain refinement to ultra-fine grains (UFGs) and improvement in strength properties. Material exhibits the following strength parameters: UTS: 129 MPa, YS: 124 MPa after deformation at f = 9.6. These values are about two times higher compared with initial state.


2018 ◽  
Vol 275 ◽  
pp. 134-146
Author(s):  
Stanislav Rusz ◽  
Ondřej Hilšer ◽  
Stanislav Tylšar ◽  
Lubomír Čížek ◽  
Tomasz Tański ◽  
...  

The technology of structure refinement in materials with the aim of achieving substantial mechanical properties and maintaining the required plasticity level is becoming increasingly useful in industrial practice. Magnesium alloys are very progressive materials for utilization in practice thanks to their high strength-to-weight ratios (tensile strength/density). The presented paper analyses the effect of the input heat treatment of the AZ31 alloy on the change of structure and strength properties through the process of severe plastic deformation (SPD), which finds an increasing utilization, especially in the automotive and aviation industry. For the study of the influence of the SPD process (ECAP method) on the properties of the AZ31 alloy, two types of thermal treatment of the initial state of the structure were selected. The analysis of the structure of the AZ31 alloy was performed in the initial state without heat treatment and subsequently after heat treatment. In the next part, the influence of the number of passes on the strengthening curves was evaluated. Mechanical properties of the AZ31 alloy after ECAP were evaluated by hardness measurement and completed by structure analysis.


2020 ◽  
pp. 93-101
Author(s):  
Serhii Bondarenko ◽  
Olexandr Grydin ◽  
Yaroslav Frolov ◽  
Olga Kuzmina ◽  
Oleksandr Bobukh

Specialists of metallurgy and mechanical engineering are intensively working at materials with controlled properties. In fact, at this stage we are already talking about the design of new materials for the specific tasks of the industry. One of the ways to achieve the regulated mechanical properties of metal products is to use the influence of plastic deformation with its different parameters in individual sections of the deformable material. In this study, we studied the effect of cold rolling on the properties of a strip of aluminum alloy EN AW-1050 with artificially created differences in the deformation parameters in different parts of the cross section of the profile. For this, a pre-shaped sample was prepared by conducting joint cold rolling of a strip of the specified material 420 mm long, 180 mm wide and 2.9 mm thick with a steel profiling tape 80 mm wide and 2 mm thick superimposed on it (length of an aluminum strip and steel profiling tape are the same). As a result of joint deformation, the steel strip rolled into the base metal and changed the geometry of the cross section and the properties of the obtained strip. Next, the obtained strip was subjected to heat treatment and rolled in a duo mill. After rolling, thin samples were made from fabricated flat strips to assess mechanical properties, in particular tensile tests were performed according to ISO 6892-1: 2009 and Brinell hardness tests were performed according to ISO 6506-1: 2014. Experimental studies of cold rolling of strips with profiled cross section of aluminum alloy EN AW-1050 were carried out. The possibility of forming heterogeneous properties in a flat aluminum strip by cold plastic deformation is shown and the maximum average values of the increase in the main indicators of mechanical properties on individual elements of the strip are determined. The maximum difference between the mechanical properties of the thick and thin elements of the profiled strip is observed in the hardness index and reaches 37.5%. The maximum obtained average value of the increase in yield strength and tensile strength is 26% and 18%, which is achieved with true deformation of the thick element of the profiled strip 0.165 and 0.234.


2014 ◽  
Vol 794-796 ◽  
pp. 431-436 ◽  
Author(s):  
Alexander Bardelcik ◽  
Alexandre Bouhier ◽  
Michael J. Worswick

To overcome the low room temperature formability of AA7075-T6 aluminum sheet, without sacrificing the high strength properties of this alloy, a hat section beam member was formed and quenched within a cold die immediately after a 20 minute solutionizing treatment. Natural aging for 24 hours followed the forming process which was then followed by various heat treatments that included a typical precipitation hardening (PH) and industrial paint bake (PB) temperature-time treatment. Tensile specimens were extracted from the beams to evaluate their mechanical properties. When compared to the as-received AA7075-T6 mechanical properties, the beams heat treated with the PH, PHPB and PB treatment resulted in a 5%, 13% and 20% reduction in ultimate tensile strength respectively. A similar trend was shown for the yield strength measurements. There was little effect of the heat treatments on the total elongation, with the PH condition showing a slight improvement. A backing plate was riveted to the beams and a quasi-static 3 point bend test was conducted to evaluate the crush performance. The peak load for the PH, PHPB and PB beams was 9.2, 8.5 and 7.3 kN respectively, but the calculated energy-displacement (or energy absorption) curves were similar for the PH and PHPB parts due to a more ductile fracture behavior for the PHPB material condition.


2010 ◽  
Vol 638-642 ◽  
pp. 1952-1958 ◽  
Author(s):  
Rustam Kaibyshev ◽  
Elena Avtokratova ◽  
O.S. Sitdikov

Effect of intense plastic straining on rollability and service properties of an Al-6%Mg-0.3%Sc alloy was examined. Ultrafine-grained structure (UFG) was produced by equal-channel angular pressing (ECAP) to a strain of 8 at a temperature of 325oC. The formation of UFG structure resulted in increase in the yield stress from 223 MPa to 285 MPa and ultimate stress from 350 MPa to 389 MPa in comparison with initial hot extruded condition. Total elongation slightly decreased from 33% to 29%. After ECAP, the material was subjected to cold and isothermal warm rolling. The formation of UFG structure resulted in enhanced rollability of the present alloy at room temperature. Cold rolling with high reduction provides the development of heavily deformed microstructure with high dislocation density, while the isothermal warm rolling does not remarkably affect the microstructure produced by ECAP. The mechanical properties after ECAP and ECAP with subsequent isothermal rolling were roughly similar. In contrast, cold rolling to the same strain resulted in significant increase of yield stress (495 MPa) and ultimate stress (536 MPa). Total elongation attained was 13%.


2010 ◽  
Vol 667-669 ◽  
pp. 851-856 ◽  
Author(s):  
Alexey Reshetov ◽  
Alexander Korshunov ◽  
A. Smolyakov ◽  
Yan Beygelzimer ◽  
Viktor Varyukhin ◽  
...  

The influence of multipass processing by Twist Extrusion (TE) on distribution of mechanical properties by volume in commercially pure (CP) titanium billets is investigated. Experiments show that the mechanical properties are almost homogeneous in the billet cross-section already after the second pass of TE. This can be explained by mixing effect and saturation of properties as well. Warm TE leads to the formation of high strength properties in combination with high plasticity. Ultimate and yield stresses of the billet processed by two cycles of TE increased, in comparison with initial state, by 30% and 60% respectively. The value of the reduction in area remained at the initial value. This fact is indicating a high technological plasticity of the material, i.e. its ability for further shaping by metal forming methods.


2016 ◽  
Vol 838-839 ◽  
pp. 392-397 ◽  
Author(s):  
Pavel Kusakin ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev ◽  
Dmitri Molodov

The influence of thermo-mechanical treatment consisting of cold rolling followed by recrystallization annealing on the grain size and mechanical properties of a high-Mn TWIP steel was studied. An Fe-23Mn-0.3C-1.5Al TWIP steel (wt. %) was subjected to extensive cold rolling with a reduction of 80% (true strain of ∼1.6) and then annealed in the temperature interval ranging from 400 to 900 °C during 20 minutes. Recovery processes took place below 500 °C, partial recrystallization was evident at ~550°C and fully recrystallized structure evolved after annealing at 600 °C and higher. The static recovery resulted in a slight decrease in the yield strength from 1400 MPa to 1250 MPa and the ultimate tensile strength from 1540 MPa to 1400 MPa whereas the total elongation of 4% did not changed. The recrystallization development led to a drastic drop of strength and an increase in ductility. The yield strength of 225 MPa, the ultimate tensile strength of 700 MPa and the total elongation of 79% was obtained after annealing at 900 °C. Correspondingly, the grain size increased from 0.2 μm to 6.2 μm with increase in anneal temperature from 550 to 900°C.


2021 ◽  
Vol 63 (1) ◽  
pp. 48-54
Author(s):  
Ömer Faruk Murathan ◽  
Kemal Davut ◽  
Volkan Kilicli

Abstract In this study, the effect of austenitizing temperatures and low-temperature isothermal heat treatment (below martensite start temperature) on the microstructure and mechanical properties of AISI 9254 high silicon spring steel has been investigated. Experimental studies show that ultra-fine carbide-free bainite, tempered martensite and carbon enriched retained austenite could be observed in isothermally heat-treated samples where the as-received sample consisted of fine pearlite. A high tensile strength of ~2060 MPa, a total elongation of ~8 %, and absorbed energy of 105 J were achieved in a commercial high-Si steel by austempering below the Ms temperature. A good combination of strength and ductility has been obtained in prolonged austempering below the martensite start temperature (225 °C) from an austenitizing temperature of 870 °C.


Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 776 ◽  
Author(s):  
Vladimir Torganchuk ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev

The microstructures and mechanical properties of Fe-0.4C-18Mn and Fe-0.6C-18Mn steels subjected to large strain cold rolling followed by annealing were studied. Cold rolling with a total reduction of 86% resulted in substantial strengthening at expense of plasticity. The yield strength and the ultimate tensile strength of above 1400 MPa and 1600 MPa, respectively, were achieved in both steels, whereas total elongation decreased below 30%. Subsequent annealing at temperatures above 600 °C was accompanied with the development of recrystallization leading to fine-grained microstructures with an average grain size of about 1 μm in both steels. The fine-grained steels exhibited remarkable improved mechanical properties with a product of ultimate tensile strength by total elongation in the range of 50 to 70 GPa %. The fine-grained steel with relatively high carbon content of 0.6%C was characterized by ultimate tensile strength well above 1400 MPa that was remarkably higher than that of about 1200 MPa in the steel with 0.4%C.


2011 ◽  
Vol 674 ◽  
pp. 129-134 ◽  
Author(s):  
Kinga Rodak ◽  
Jacek Pawlicki ◽  
Krzysztof Radwański ◽  
Rafal M. Molak

In this study, commercial Cu was subjected to plastic deformation by compression with oscillatory torsion. Different deformation parameters were adopted to study their effects on the microstructure and mechanical properties of Cu. The deformed microstructure was characterized by using scanning electron microscopy (SEM) equipment with electron backscattered diffraction (EBSD) facility and scanning transmission electron microscopy (STEM). The mechanical properties were determined on an MTS QTest/10 machine equipped with digital image correlation. Can be found, that process performed at high compression rate and high torsion frequency is recommended for the refining grain size. The size of structure elements: average grain size (D) and subgrain size (d) reached 0.42 m and 0.30 m respectively, and the fraction of high angle boundaries was 35%, when the sample was deformed at a torsion frequency f= 1.6 Hz and compression rate v=0.04 mm/s. Deformation at these parameters leads to an improvement in strength properties. The strength properties are about two times greater than the initial state.


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