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The grain size was about 1㎛, and no more grain refining was found even after 14-pass of ECAR.
Generally, the average grain size increases as deformation temperature goes up.
The number of crack-like surface defects is reduced by warm temperature deformation.
However, heat treated only at 440℃ also shows a good grain structure.
The processing speed is also improved by reducing the repeating number of low speed ECAR

The grain boundary suffers severe corrosion, moreover, a number of grains peel off, i.e. the dark spots in Fig.2(a).
It is because the strength that makes grains interconnected decrease sharply after the grain boundary is eroded, leading to great separation of grains.
However, the number of IGC signals is much more than that in [3].
Therefore, it is very possible that different testing methods result in different number of AE signals.
Xu [3] did not explore the AE source due to the low AE activity and poor numbers of signals.

A large number of blocky ferrite formed due to the increase of chromium level in the matrix.
The bigger secondary particles were mainly present at grain boundaries, while the smaller ones mainly distributed in grain interiors.
A large number of blocky ferrite formed due to the increase of chromium level in the matrix which can expand ferrite phase region.
It can be seen that secondary particles precipitated along grain-boundary and formed into chains in the steel tempered at 600°C.
A large number of blocky ferrite formed due to the increase of chromium level in the matrix.

The alloyed steels displayed an increase in the number of grains containing shear bands and strengthening of the {111} component after warm rolling compared to an unmodified low carbon steel [7].
Discussion The recrystallisation process and the final recrystallisation texture depend on the stored energy and the number and configuration of dislocations present in the deformed material.
The stored energy level is sensitive to the number of interstitial atoms present in the plane.
The higher values of stored energy in the LC steel are related to the higher amount of carbon in solid solution and, in turn, to the lower number of grains containing shear bands.
As reported by Barnett [13], a small number of deformed grains containing shear bands promoted the formation of a weak {111} recrystallisation component in this steel since the γ fibre forms preferentially at shear band boundaries.

The grain size continues to increase significantly at 900ºC where the grain size is almost twice than the grain size observed at 800ºC.
The grains are now densely packed to each other with no uniformity in terms of the grain growth.
The grain growth attributed from these two factor would result in the increase in the number of domain walls in larger grains.
The impact of wall movement towards magnetization or demagnetization will be larger than that of domain rotation as the number of domain walls continues to increase.
The presence of greater numbers of domain walls as a result of grain growth leads to the increase in the magnetic saturation.

The abnormal grain growth is well known may be suppressed by a pre-straining treatment.
FSW resulted in drastic grain refinement in stir zone, as shown in Fig. 3a.
The evolved microstructure was characterized by nearly equiaxed grains with the mean grain size of 5.7 mm.
It is clear that the pre-strain suppressed the abnormal grain growth effectively.
Specifically, the pre-strain rolling along the WD was most effective for inhibition of the abnormal grain growth Acknowledgements This work is supported by the Ministry of Education and Science of the Russian Federation under the agreement №14.584.21.0023 (ID number RFMEFI58417X0023).

Grain Refinement Mechanism of Al-5Ti-1B Master Alloy by ab initio Calculations HanLong Zhanga, Yanfeng Hanb*, Jun Wangc, Yongbing Daid and Baode Sune State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Shanghai 200240, People’s Republic of China ahanccyy@sjtu.edu.cn, byfhan@sjtu.edu.cn, cjunwang@sjtu.edu.cn, dybdai@sjtu.edu.cn, ebdsun@sjtu.edu.cn Keywords: Grain Refinement; Al-Ti-B Master Alloy; Interface; Ab initio simulation Abstract.
Introduction Fine equiaxed grains are most preferable for alloys being used at room temperature.
Grain refinement by the inoculation of Al-5Ti-1B master alloy into the melt of aluminium alloys has become the most popular practice in industry [1].
However, their experimental conditions are quite different from the real grain refinement practice in industry.
It is defined as follows: , (2) where Axy is the area of interface, Δz is the increment along Z direction and is the time-averaged number of atoms between z-Δz/2 and z+Δz/2.

Volume percent of grains in wheel is about 54~58%.
So the number of grains on the working surface of the wheel per unit millimeter is N=1.66mm-1.
When the workpiece was ground by wheel with a speed of 1350rpm, the number of grains passes through the grinding zone per unit time can be gotten: .
Each grain has different exposed heights.
Then these active grains would produce “flash” impulses.

All these techniques resulted in pronounced grain refinement.
Currently, austenitic stainless steels are widely used for a number of structural applications [3].
This microstructure is composed of alternating nano-scale austenite and matrensite grains.
Only austenitic nano-scale grains with an average size of ~23 nm evolve during HPT (Fig. 1c).
Langdon, Twenty-five years of ultrafine-grained materials: Achieving exceptional properties through grain refinement.

In the absence of such a simple relationship we have therefore in the present work run a large number of simulations where we systematically, over a large range of values, have varied the stored energy, the nucleus size and the initial grain size.
First a microstructure is mapped onto a 3D lattice where each lattice site is assigned a number Si, which has a value between 1 and Q.
Si corresponds to the orientation of the grain, and Q is the total number of orientations.
In the following we have therefore carried out a large number of simulations where these parameters have been varied systematically.
The plot shows average initial grains with size 1, 3, 9 and 20 lattice sites together with a case where one large grain occupies the entire lattice.