Static Grain Growth in an Austenitic Stainless Steel Subjected to Intense Plastic Straining

2014 ◽  
Vol 783-786 ◽  
pp. 1021-1026
Author(s):  
Marina Tikhonova ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Dynamic Recrystallization ◽  
Early Stage ◽  
Structural Heterogeneity ◽  
Continuous Dynamic Recrystallization ◽  
Multidirectional Forging ◽  
Ultrafine Grained ◽  
Heterogeneous Microstructures ◽  
Continuous Dynamic

The post-dynamic recrystallization of an ultrafine grained 304-type austenitic stainless steel was studied during annealing at 800 and 1000°C for 7.5 to 480 minutes. The initial ultrafine grained microstructures have been developed by continuous dynamic recrystallization during isothermal multidirectional forging to a total strain of ∼4 at temperatures ranging from 500 to 800°C. The post-dynamic recrystallization involves a rapid softening at early stage of annealing followed by a sluggish decrease of hardness upon further annealing. A transient recrystallization at early annealing stage results in somewhat heterogeneous microstructures in the samples subjected to previous deformation at relatively low temperatures of 500-600°C. This structural heterogeneity disappears with increasing the annealing time. Commonly, the post-dynamic recrystallization behavior can be considered as a kind of continuous recrystallization.

Regularities of Grain Refinement in an Austenitic Stainless Steel during Multiple Warm Working

2013 ◽  
Vol 753 ◽  
pp. 411-416 ◽  
Author(s):  
Andrey Belyakov ◽  
Marina Tikhonova ◽  
Zhanna Yanushkevich ◽  
Rustam Kaibyshev
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Structural Changes ◽  
Continuous Dynamic Recrystallization ◽  
Warm Working ◽  
Fine Grain ◽  
Power Law Function ◽  
Continuous Dynamic

The structural changes that are related to the new fine grain development in a chromium-nickel austenitic stainless steel subjected to warm working by means of multiple forging and multiple rolling were studied. The multiple warm working to a total strain of 2 at temperatures of 500-900C resulted in the development of submicrocrystalline structures with mean grain sizes of 300-850 nm, depending on processing conditions. The new fine grains resulted mainly from a kind of continuous reactions, which can be referred to as continuous dynamic recrystallization. Namely, the new grains resulted from a progressive evolution of strain-induced grain boundaries, the number and misorientation of which gradually increased during deformation. In contrast to hot working accompanied by discontinuous dynamic recrystallization, when the dynamic grain size can be expressed by a power law function of temperature compensated strain rate as D ~ Z-0.4, much weaker temperature/strain rate dependence of D ~ Z-0.1was obtained for the warm working.

Continuous Dynamic Recrystallization of AISI 430 Ferritic Stainless Steel by Hot Torsion Deformation

2005 ◽  
Vol 475-479 ◽  
pp. 145-148 ◽  
Author(s):  
Jae-Young An ◽  
Suk Min Han ◽  
Young Jae Kwon ◽  
Yeon Chul Yoo
Keyword(s):  
Stainless Steel ◽  
Flow Stress ◽  
Dynamic Recrystallization ◽  
Ferritic Stainless Steel ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
High Angle ◽  
Continuous Dynamic Recrystallization ◽  
Continuous Dynamic ◽  
Aisi 430

The high temperature deformation behavior of AISI 430 ferritic stainless steel has been studied over a temperature range of 800 to 1000°C and strain rate of 0.05-5.0/sec. The evolution of flow stress and microstructures showed the characteristics of continuous dynamic recrystallization (CDRX). The flow stress curves gradually decreased with increasing strain over the peak stress until 500% of strain without any steady state shown in typical austenitic stainless steel. Sub-grains of low angle firstly formed along the original high angle grain boundary were propagated into the inside of original grain and transformed to high angle. The CDRX grain sizes of AISI 430 deformed at 1000 °C and 0.5/sec was about 30-35㎛.

Continuous Dynamic Recrystallization in Dual-Phase Titanium Alloy in Superplasticity

2018 ◽  
Vol 385 ◽  
pp. 126-130 ◽  
Author(s):  
Keita Sekiguchi ◽  
Hiroshi Masuda ◽  
Hirobumi Tobe ◽  
Eiichi Sato
Keyword(s):  
Titanium Alloy ◽  
Dynamic Recrystallization ◽  
Early Stage ◽  
Continuous Dynamic Recrystallization ◽  
New Class ◽  
Β Phase ◽  
Α Phase ◽  
Slip Planes ◽  
The Difference ◽  
Continuous Dynamic

A new class of superplastic titanium alloy, Ti–4.5Al–2.5Cr–1.2Fe–0.1C–0.3Cu–0.3Ni, was deformed at 1073 K with strain rates of 1×10−4–1×10−1 s−1, and microstructures in the condition between superplastic regions II and III (= 1×10−2 s−1) were observed using scanning electron microscope and electron back-scattered diffraction. Continuous dynamic recrystallization was observed, resulting in grain refinement both in α and β phases. The grain size decreased significantly in α phase at the early stage of the deformation and in β phase at the later stage. In the recrystallized microstructure, the major sub-boundaries formed perpendicularly to slip directions <11−20> in α phase and parallel to slip planes {110} in β phase, which might be caused by the difference in the symmetry of the crystal structures.

Grain Refinement in Austenitic Stainless Steel during Warm Screw Rolling

2012 ◽  
Vol 715-716 ◽  
pp. 889-894
Author(s):  
Anna Mogucheva ◽  
Nikolay Lopatin ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
Volume Fraction ◽  
Screw Rolling ◽  
Structural Mechanism ◽  
Continuous Dynamic Recrystallization ◽  
Area Reduction ◽  
The Difference

The development of dynamic recrystallization in a 304-type austenitic stainless steel during warm multi-pass screw rolling was studied. The fraction recrystallized depended significantly on the distance from the centre of rolled rods. The highly elongated original grains were mainly observed in the centre of processed samples, while the portions close to the sample edge were characterized by relatively fast development of dynamic recrystallization leading to formation of almost equiaxed fine grains with a size of about 1 μm. The volume fraction of fine grains in the edge areas increased with straining and exceeded 0.7 after rolling to 63% cross area reduction. The structural mechanism responsible for the grain refinement was considered as continuous dynamic recrystallization. The difference in the recrystallization kinetics across the sample is associated with the variation in strain intensity.

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