Heat Treatment and Thermo-Mechanical Treatment to Modify Carbide Banding in AISI 440C Steel: A Case Study

2016 ◽  
Vol 5 (2) ◽  
pp. 108-115 ◽  
Author(s):  
S. Chenna Krishna ◽  
K. Thomas Tharian ◽  
K. V. A. Chakravarthi ◽  
Abhay Kumar Jha ◽  
Bhanu Pant
Author(s):  
Antoni Świć ◽  
Arkadiusz Gola ◽  
Łukasz Sobaszek ◽  
Natalia Šmidová

AbstractThe article presents a new thermo-mechanical machining method for the manufacture of long low-rigidity shafts which combines straightening and heat treatment operations. A fixture for thermo-mechanical treatment of long low-rigidity shafts was designed and used in tests which involved axial straightening of shafts combined with a quenching operation (performed to increase the corrosion resistance of the steel used as stock material). The study showed that an analysis of the initial deflections of semi-finished shafts of different dimensions and determination of the maximum corrective deflection in the device could be used as a basis for performing axial straightening of shaft workpieces with simultaneous heat treatment and correction of the initial deflection of the workpiece. The deflection is corrected by stretching the fibers of the stock material, at any cross-section of the shaft, up to the yield point and generating residual stresses symmetrical to the axis of the workpiece. These processes allow to increase the accuracy and stability of the geometric shape of the shaft.


2014 ◽  
Vol 1760 ◽  
Author(s):  
Akira Umise ◽  
Masaki Tahara ◽  
Kenji Goto ◽  
Tomonari Inamura ◽  
Hideki Hosoda

ABSTRACTIn order to improve shape memory properties of Au-Cu-Al based shape memory alloys, the possibility to utilize thermo-mechanical treatment was investigated in this study, and effects of heat-treatment temperature on microstructure, martensitic transformation and mechanical properties of cold-rolled Au-30Cu-18Al-2Fe (AuCuAlFe) alloy were clarified by X-ray diffraction analysis (XRD, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and tensile tests at room temperature (RT). Here, Fe addition to AuCuAl improves ductility. Cold rolling with the thickness reduction of 30% was successfully carried out in AuCuAlFe at RT. An exothermic heat was observed in DSC at temperature from 402K, suggesting that recovery started at 402K. Besides, the transformation temperature hysteresis increased by the cold-rolling. The alloy was completely recrystallized after the heat treatment at 573K for 3.6ks. Tensile tests revealed that the yield stress was raised by cold rolling and largely by the subsequent heat treatment at 433K, which corresponded to the recovery start temperature by DSC. The yield stress decreased with increasing heat treatment temperature over 453K, probably due to recrystallization. AuCuAlFe cold-rolled and subsequent heat-treated at 573K exhibited the lowest yield stress as well as stress-plateau region, indicating that the thermo-mechanical treatment is effective to improve shape memory properties of Au-Cu-Al based alloys.


2010 ◽  
Vol 659 ◽  
pp. 349-354
Author(s):  
Péter János Szabó

The relative fraction of the special grain boundaries can be increased by thermo-mechanical treatments. During this work, AISI 304-type austenitic stainless steels were plastically deformed and heat treated under different conditions, and then the grain boundary network, which developed during the treatments was investigated. Results showed that cyclic application of large cold rolling (30% reduction of thickness) and quick heat treatment at high temperature (800 °C, 2 minutes) gave the best grain boundary network. A possible reason of this behaviour is that grains which did not recrystallize after the first cycle, stored a high elastic energy, which helped the grain boundary motions in the next cycles. To characterize the developed grain boundary network, different parameters are also suggested in this paper.


2011 ◽  
Vol 284-286 ◽  
pp. 1621-1625 ◽  
Author(s):  
Bai Ping Mao ◽  
Jun Peng Li ◽  
Jian Shen

Effects of thermo-mechanical treatment on the mechanical properties and microstructure of 2197 alloy were studied through analyses of the mechanical properties by tensile tests and TEM observation of thermo-mechanical heat treated 2197 alloy plates of various states. Results show that the dominating precipitated phase of peak-aged 2197 alloy during thermo-mechanical heat treatment is T1 phase of which the size is 50~150nm. The precipitation and growth of T1 phase are accelerated due to the existed nucleation sites for heterogeneous nucleation of T1 phase offered by thermo-mechanical treatment, therefore, the time for 2197 alloy to reach the peak-aged state is shorten. The strength of 2197 alloy for peak-aged state is increased through thermo-mechanical treatment because the strengthening effect of T1 phase with higher aspect ratio is bigger than that of δ′ and θ′ phases.


Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1034 ◽  
Author(s):  
Andrey Medvedev ◽  
Alexander Arutyunyan ◽  
Ivan Lomakin ◽  
Anton Bondarenko ◽  
Vil Kazykhanov ◽  
...  

This paper focuses on the mechanical properties, electrical conductivity and fatigue performance of ultra-fine-grained (UFG) Al-Mg-Si wires processed by a complex severe plastic deformation route. It is shown that the nanostructural design via equal channel angular pressing (ECAP) Conform followed by heat treatment and cold drawing leads to the combination of enhanced tensile strength, sufficient ductility, enhanced electrical conductivity, and improved fatigue strength compared to the wires after traditional T81 thermo-mechanical treatment used in wire manufacturing. The Processing-microstructure-properties relationship in the studied material is discussed.


2013 ◽  
Vol 376 ◽  
pp. 163-172 ◽  
Author(s):  
Mahmoud M. Tash ◽  
S. Alkahtani

The present study was undertaken to investigate the effect of Thermo-mechanical Treatment (TMT) on aging and hardness of Al-Mg-Si (6082) alloys. The effect of cold work after solution treatment, aging time and temperature on the microstructure and hardness were studied. Hardness measurements were carried out on specimens prepared from 6082 alloys in the as solution treated specimens and heat-treated conditions, using different cold work percentage before aging treatment. Aging treatments were carried out for the as solution treated specimens (after quenching in water) as well as for the as cold worked specimens (after solution treatment and quenching in water). The specimens were aged at different conditions; Natural aging was carried out at room temperature for different periods of time. Artificial aging was performed at 100 °C, 150 °C, and 200 °C for various times. It is noticed that cold work, following solution treatment, accelerates the precipitation rate leading to a rise in strength.A statistical design of experiments (DOE) approach using fractional factorial design was applied to determine the influence of controlling variables of cold work and heat treatment parameters and any interactions between them on the hardness of 6082 alloys. A mathematical model is developed to relate the alloy hardness with the different metallurgical parameters i.e. Cold work prior solution heat treatment (CWBSHT), Cold work after solution heat treatment (CWASHT), Pre-aging Temperature (PA T0C), Pre-aging time (PA t h), Aging temperature (AT0C), Aging time (At h), Cold work after aging treatment (CWAAT), Annealing temperature (An.T0C) and Annealing time (An.t min) to acquire an understanding of the effects of these variables and their interactions on the hardness of Al-Mg-Si 6082 alloys.


2010 ◽  
Vol 638-642 ◽  
pp. 2610-2615 ◽  
Author(s):  
Henryk Dyja ◽  
Bartosz Koczurkiewicz ◽  
Marcin Knapiński

In the present work, low-carbon ultra grained constructional low-alloyed steel were subjected to thermo-mechanical treatment for modification of microstructure. It shows that microstructure after thermo-mechanical treatment is quite dependent on the alloy composition, conditions of hot deformation, grain size of austenite and cooling rate. The research was provide by using the computer program for thermo and thermo – mechanical treatment. The most optimal variant of heat treatment and thermo – mechanical deformation were obtained. The verifications were provided by the dilatometer with possibility of deformation DIL 805A/D.


2015 ◽  
Vol 1101 ◽  
pp. 212-216
Author(s):  
Mahmoud M. Tash ◽  
Saleh A. Alkahtani ◽  
Khaled A. Abuhasel

The present study was undertaken to investigate the effect of thermo-mechanical treatment (TMT) on the mechanical behaviour of different grades of low alloy steels. The effect of hot forming (rolling) with different reduction ratios on the hardness and impact toughness properties will be studied. Correlations between different thermo-mechanical treatment parameters, hardness and impact toughness for different grades of low alloy steels were carried out. Different grades of Low alloy steels were selected for the present study. An extensive study will be carried out to investigate the effect of alloying additions and TMT parameters on the hardness and impact toughness of heat-treated low alloy steels. An understanding of the combined effect of TMT and heat treatment on the mechanical properties of the low alloy steels would help in selecting conditions required to achieve optimum mechanical properties and alloy high strength to weight ratio. The scope of the present work is therefore to study the effects of hot rolling reduction ratios on microstructure and mechanical properties of such alloys. By measuring hardness, impact toughness, strength and ductility resulting from different heat treatment following TMT, it is possible to determine which conditions yielded optimum mechanical properties and high strength to weight ratio.


2011 ◽  
Vol 264-265 ◽  
pp. 1725-1730 ◽  
Author(s):  
Jan Džugan ◽  
Z. Nový ◽  
Martina Sosnová

The investigated 34CrNiMo steel is traditionally used for highly loaded components with very high hardenability, fatigue strength and toughness. There were obtained very good experiences with this material, therefore there is no demand for change of the material, but for the material full potential utilization. This goal could be attained by application of thermo-mechanical treatment to the material of interest. There are compared several materials states obtained by conventional thermal treatment with new thermo-mechanically processed states in the current study. Conventionally treated materials exhibit about half tensile strength of the material after the thermomechanical treatment. The material fatigue life is related to tensile strength of the material. Therefore for representative comparison it is useful to compare materials with similar tensile properties, if the advantage of thermomechanical over heat treatment is to be evaluated. Samples of material of similar tensile strength to thermomechanically treated state were prepared by heat treatment. Fatigue tests were performed for traditionally treated samples with thermomechanically treated state and heat treated state. Thermo-mechanically treated state exhibits superior strength and fatigue life in comparison to all other states investigated. There was also performed metallographical investigation of microstructures of compared states providing information on what sort of microstructures were obtained by which treatment, that could be related to mechanical properties. The study presented here shows potential of thermo-mechanical treatment of traditionally used steels.


Author(s):  
L.E. Murr

Ledges in grain boundaries can be identified by their characteristic contrast features (straight, black-white lines) distinct from those of lattice dislocations, for example1,2 [see Fig. 1(a) and (b)]. Simple contrast rules as pointed out by Murr and Venkatesh2, can be established so that ledges may be recognized with come confidence, and the number of ledges per unit length of grain boundary (referred to as the ledge density, m) measured by direct observations in the transmission electron microscope. Such measurements can then give rise to quantitative data which can be used to provide evidence for the influence of ledges on the physical and mechanical properties of materials.It has been shown that ledge density can be systematically altered in some metals by thermo-mechanical treatment3,4.


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