scholarly journals Investigation of Thermomechanical Processing of Nb Microalloyed Steel Produced by Powder Metallurgy

2021 ◽  
Author(s):  
Demet TAŞTEMÜR ◽  
Süleyman GÜNDÜZ
Keyword(s):  
Powder Metallurgy ◽  
Thermomechanical Processing ◽  
Microalloyed Steel ◽  
Nb Microalloyed Steel

Thermomechanical Processing of a Nb-Microalloyed Steel in a Controlled-Forging Treatment

2011 ◽  
Vol 409 ◽  
pp. 835-840 ◽  
Author(s):  
Davood Nakhaie ◽  
Pooya Hosseini Benhangi ◽  
Mohammad Mazinani ◽  
Fateh Fazeli ◽  
Mahmoud Reza Ghandehari Ferdowsi
Keyword(s):  
Grain Refinement ◽  
Hot Deformation ◽  
Thermomechanical Processing ◽  
Microalloyed Steel ◽  
Hot Forging ◽  
Constant Strain Rate ◽  
Microalloyed Steels ◽  
Strengthening Effect ◽  
Cooling Rates ◽  
Nb Microalloyed Steel

Ferrite grain size is one of the most important microstructural parameters in steels which can be appropriately adjusted to cause a significant strengthening effect. Thermomechanical processing is an effective method for ferrite grain refinement in microalloyed steels. Transformation of deformed austenite with a pancaked grain structure to a relatively fine ferrite phase is an important phenomenon occurring during the thermomechanical processing of microalloyed steels. The final microstructure of steels can be optimized by controlling three critical processing parameters, i.e. i) applied strain (constant strain rate), ii) deformation temperature, and iii) cooling rates following the hot deformation stage. In the present study, a new approach (called controlled-forging treatment) consisting of hot deformation of steel at the austenitic temperature range using an upset forging stage was developed for the ferrite grain refinement in a Nb-microalloyed steel. The investigated steel was subjected to a thermomechanical treatment including reheating, hot deformation for two different strain levels, namely 30 and 50% reductions of height, in a single pass hot-forging stage at temperatures below the TNR(no-recrystallization) and above the TR3(austenite to ferrite transformation) temperatures followed by cooling to room temperature using three different cooling rates. The experimental results obtained from this proposed treatment were more or less similar to those already obtained for the case of controlled-rolling process on Nb-microalloyed steel sheets.

Determination of Austenite Grain Coarsening Temperature of a Nb-Microalloyed Steel Sheet

2011 ◽  
Vol 213 ◽  
pp. 600-603
Author(s):  
Daavood Mirahmadi Khaki ◽  
Vahid Alizaadeh Otaaghvar ◽  
Masoud Mirahmadi Khaki
Keyword(s):  
Thermomechanical Processing ◽  
Microalloyed Steel ◽  
Controlled Rolling ◽  
Grain Structure ◽  
Grain Coarsening ◽  
Steel Rolling ◽  
Steel Sheets ◽  
Fine Grain ◽  
Nb Microalloyed Steel ◽  
Hot Rolled

Thermomechnical processing and controlled rolling of microalloyed steel sheets are affected by several factors according to the final properties of product. To create the high mechanical properties, a uniform and fine-grain structure is necessary in hot rolled final products. To produce such microstructures, every stage of the thermomechanical processing of the steel rolling has to be carefully controlled. Hence, first step is grain coarsening control that it usually occurs during reheating for slab. For this purpose, seven different reheating temperatures between 1000 to 1300 °C with 50 °C increments were chosen in this investigation for soaking treatment. By soaking the specimens in furnace, the grain coarsening temperature (Tgc) is obtained about 1250 °C. Moreover, it is observed that increasing the reheating temperatures causes more decreasing of the precipitates percentage. Hence, for these kinds of steels, the reheating temperature 1200 to 1250 °C is recommended.

Effect of Controlled Hot Rolling Parameters on Microstructure of a Nb-Microalloyed Steel Sheet

2011 ◽  
Author(s):  
Daavood Mirahmadi Khaki ◽  
Amir Abedi ◽  
Francisco Chinesta ◽  
Yvan Chastel ◽  
Mohamed El Mansori
Keyword(s):  
Hot Rolling ◽  
Steel Sheet ◽  
Microalloyed Steel ◽  
Nb Microalloyed Steel

Microstructure Characteristics in Continuous Cooling Transformation of an Nb Microalloyed Steel

2011 ◽  
Vol 228-229 ◽  
pp. 72-76
Author(s):  
J. H. Yang ◽  
Q. Y. Liu
Keyword(s):  
Microalloyed Steel ◽  
Controlled Rolling ◽  
Controlled Cooling ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Microstructure Characteristics ◽  
Continuous Cooling ◽  
Nb Content ◽  
Nb Microalloyed Steel ◽  
Two Stages

Deformation dilatometry has been used to simulate controlled hot rolling followed by controlled cooling of a Nb microalloyed pipeline steels, the microstructure and transformation characteristics in the steel and the effect of deformation on transformation are studied. According to the results of both dilatometry measurements and microstructure observations, the continuous cooling transformation curves (CCT) of the tested steels are constructed. The results show that Nb content and deformation enhance the formation of acicular ferrite; the microstructure of the steel range from PF, QF to AF with increasing of cooling rates from 0.5 to 50°C /s in a two stages controlled rolling and the microstructure revolution is sensitive to cooling rates when it is lower than 5°C /s, however, when the cooling rate increasing further, the microstructure didn’t change very much but M/A constituents in matrix is refined and dispersed.

Structural Effects of Thermomechanical Processing on the Static and Dynamic Responses of Powder Metallurgy Fe-Mn-Si Based Shape Memory Alloys

2016 ◽  
Vol 97 ◽  
pp. 153-158 ◽  
Author(s):  
Elena Mihalache ◽  
Bogdan Pricop ◽  
Radu Ioachim Comăneci ◽  
Marius Gabriel Suru ◽  
Nicoleta Monica Lohan ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Structural Changes ◽  
Thermomechanical Processing ◽  
Mechanical Analysis ◽  
Dynamic Responses ◽  
Surface Areas ◽  
Specimen Holder ◽  
Hot Rolled

Fe-14Mn-6Si-9Cr-5Ni (wt. %) shape memory alloys (SMAs) were produced by powder metallurgy (PM) combined with Mechanical Alloying (MA). The specimens were pressed and sintered under Ar atmosphere from as blended powders as well as from mixtures of as blended and 10, 20, 30 and 40 vol. % MA’ed powders, respectively. The five groups of sintered specimens were hot-rolled, spark-erosion cut and solution treated at five temperatures (923, 1023, …, 1373K/ 300 s/ water). Tensile loading-unloading tests were performed in order to obtain stress-induced martensite at different pre-straining degrees. The static responses of the twenty five types of specimens were evaluated by means of the surface areas under unloading curve (E2) and between loading and unloading curves (E1) which were used for determining static internal friction, Q-1. The dynamic responses of the undeformed specimens were determined by Dynamic Mechanical Analysis (DMA) performed at room temperature with a three-point-bending specimen holder in strain sweep mode. The structure of the twenty five specimens was analyzed X-ray diffraction. The effects of MA fraction were correlated with static and dynamic responses via structural changes.

TECHNOLOGICAL WAYS TO CREATE COMPOSITE MATERIALS BASED ON HEAT-RESISTANT REFRACTORY COMPOUNDS (review)

2021 ◽  
pp. 12-20
Author(s):  
A.V. Shestakov ◽  
◽  
M.M. Karashaev ◽  
N.S. Dmitriev ◽  
◽  
...  
Keyword(s):  
Composite Materials ◽  
Powder Metallurgy ◽  
Thermomechanical Processing ◽  
Technological Plasticity ◽  
Heat Resistant ◽  
System A ◽  
Refractory Compounds ◽  
Similar Materials ◽  
Powder Metallurgy Methods ◽  
Rocket Technology

The article discusses the main technological approaches to obtain heat-resistant and heat-resistant materials based on compounds in the Ni–Al system in order to use them in promising products of aviation and rocket technology. It is shown that when receiving materials based on compounds in the Ni-Al system, a phase of eutectic origin is formed based on the Ni3Al compound, which reduces the technological plasticity of the alloys of this system. The use of powder metallurgy methods eliminates such phases in the structure of alloys obtained using granule metallurgy technology, as well as with the use of special methods of powder metallurgy. Technological approaches are presented to obtain similar materials using powder metallurgy methods combined with thermomechanical processing.

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