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PF and FSP appeared only in a few grain boundaries and were small amounts.
Accounted for most of the field was still a large number of acicular ferrite.
Compared with primary structure, the grains of PF, FSP and AF coarsened in overheated zone.
Within the grain, there was uniform acicular ferrite, the maximum length of which was 15μm.
Compared with overheated zone, the grains of PF and AF were fined in normalized zone.

Introduction Austenitic stainless steels constitute the largest stainless steel family in terms of number of alloys and usage.
Palanichamy et al. [6] have reported the use of longitudinal and shear wave velocity measurements for average grain size estimation in austenitic stainless steel.
It was observed that equi-axed grain size was observed initially (Fig.1), which turned elongated after rolling operations (Fig.2-4).
If there is further no change in velocity it means the grains becomes constant and it has played a decisive role so, ultrasonic energy is not attenuated further.
Raj, Ultrasonic velocity measurements for estimation of grain size in austenitic stainless steel, NDT&E International, 28(3) 1995 179

Although a small number of studies have investigated the oxide scale formed by early-stage oxidation of Type 304 [5-7], that of Cr-Mn-Ni stainless steel has not been studied.
For example, consider the grain boundary.
The grain boundary produces a thin oxide film on the grain boundary by a large supply of Cr and Si, which form an oxidation-protective oxide film, from the metal to the interface of the metal and oxide scale, while the grain boundary produces intergranular oxidation or internal oxidation due to an increase in oxygen supplied from the atmosphere [10].
However, it is not considered that the uneven interface is formed by the grain boundary, in view of the fact that the uneven interval, which is a few 100nm, is much smaller than the common size of recrystallization grains in stainless steels.

The mechanical properties of new zirconium alloy tubes Number Ambient temperature 375℃ Rm [MPa] Rp0.2 [MPa] A [%] Rm [MPa] Rp0.2 [MPa] A [%] 1 495 360 34.5 260 161 46.0 2 490 355 34.0 260 162 41.5 3 495 355 33.5 260 164 47.0 Test Process A standard code GB/T 2039 and CCS-Type creep testing machine were used for the creep tests.
The dimples were small and dense in the low stress, because the role of the grain boundary sliding and the dislocation line climbing would reduce, and the fracture time was longer with the stress decreasing.
A double-grain boundary occurred in the axial creep fracture for the 210MPa loading condition.
The double-grain boundary was composed of two parallel lines.
A possible reason about the double-grain boundary was that the grain boundary not only sliding along the interface but also migrating in the direction of almost perpendicular to the interface during the creep process, so the grain boundary became wider.

The ZnO varistor is the most exhaustively studied class of these ceramic materials and is commercially used as voltage suppressors in a great number of powder systems and electronic circuits [1, 2].
The grain sizes were calculated by microstructure linear analysis.
This figure shows a uniform microstructure containing WO3 grains.
It can be seen that grain sizes increas with the increase of the concentration of Y2O3, meaning that the dopant could promote grain growth.
The dielectric constant of sample is determined by the width of the grain boundary [15].

From the micrographs in Fig. 3a and 3b, it can be noted that X element addition reduces the grain size and refines the secondary phases of alloy IMR41 obviously.
The new phase in IMR41 melting point, MgmXn phase would form earlier in the melt, and it could be the heterogeneous nulei of the α phase to reduce the grain size; and because of the low solubility of X element in magnesium, rapid enrichment of solute in the liquid ahead of the growing interface could interfere with the precipitation of secondary phases and make a more dispersive phase distribution.
There are a lot of fine and dispersive intermetallic rods or plates along grain boundary, and a large number of much finer particles in the grains.
The X element brings new phase, reduces grain size, and fines secondary phases along grain boundary.

Discussion The microstructure analysis shown, that after all modes of cooling by scheme 1 the globular structure of primary α - phase and the subgrain structure with thin layers of primary α – phase within original β - grain are observed (Fig. 1).
The changing of α - phase precipitation seats in the grain body to the accretion, with a decrease in the cooling rate, is shown in the presence of nonmonotonic dependence of α - phase volume fraction at a cooling rate of 17.6 °C/min (scheme 1) and 10.8; 16.3 °C/min (scheme 2).
And second, more low-temperature transformation, in which the secondary α – phase precipitation occurs in the body of β - grain.
The level of Vickers hardness values after treatment according to scheme 1 is lower than values for similar cooling rates after the scheme 2 (with heating in the β - region), which can be explained by the presence of more defect structure after processing by scheme 1, due to which increases the number of places for the nucleation of secondary precipitations, providing their higher dispersion during aging.
The treatment according to scheme 2 (with preheating in β - region) is undesirable, as in this case there is no significant gain in hardness, but the problems with plasticity can occur due to the enlargement of β - matrix grain.

The reservoirs are divided into a number of semi-connected or not connected flow units due to the presence of interlayer to control the movement of the fluids [1,5].
Muddy interlayer has low permeability, high packer ability, as well as high displacement pressure, which are likely developed in the depositional regions with more fine-grained sediments.
During lake transgression process, accommodate space increases and water become deeper, muddy interlayer can be formed by directly overlying sandstone and shale owing to sediment grain size tapering.
Physical interlayer belongs to a class of strata because clay content formations and sediment grain size changes, resulting in the lateral deterioration of the porosity and permeability, including fine-grained sandstone, siltstone and fine conglomerates contain more fine-grained material and poor sorting of sandstone (Fig.1B).
Thick and fine-grained sediments occur mixed deposition with physical changes in the lateral fast and prone to physical dissection.

Under heat treatment at 1500oC, a number of smaller mullite grains was observed in Fig. 3 (b), and ZrO2 was relatively evenly distributed among them.
It can be seen from the Fig. 3 (c), the heat treatment temperature rose to 1550oC, the edges and corners of mullite began to become clear with the small columnar mullite grains appearing.
Columnar mullite grains abnormal grew up significantly at heat treatment temperature of 1600oC, which is showed in Fig. 3 (d).
When the heat treatment temperature incresed to 1500 oC, the sample continued to melt, and the white isometric ZrO2 grain and gray irregular mass of Al2O3 grain dispersed, as shown in Fig. 4 (c).
When the temperature rose to 1600 oC, a part of t-ZrO2 transformed into m phase, and the grain grew up gradually.

The appropriated factors of deep rolling process for JIS SS400 MIG welding were rolling pressure 270 MPa, rolling speed 1,500 mm/min and number of passes 3 times.
The experimental design of the Taguchi method has been widely used as it can reduce the number of trials to a minimum, thus saving costs and time [8].
Factors that are expected to affect the surface residual stress after the deep rolling process are three factors: rolling pressure, rolling speed and the number of passes.
Parameters Unit Level Symbol Low (+1) High (+2) Rolling pressure Bar 100 270 A Rolling speed mm/min 500 1,500 B Number of passes time 1 3 C Table 5.
It could be concluded that the rolling pressure from the deep rolling process creates deep plastic deformations, the applied pressure creates work hardening and strain hardening by inducing dislocation pile-up due to stuck dislocations across a grain through a narrow transition zone or grain boundary as an effective slip barrier, which can create a compressive residual stress and also improve microhardness of the material.