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The steel shall be fully killed and made with fine grain structure with a grain size of ASTM 7 or finer as per ASTM E 112.
Table 4 Vicker hardness test result (HV10) Sample Location Vicker hardness test result (HV10) 1 2 3 4 5 6 7 8 9 Pipe body 229 226 222 238 237 237 241 226 227 Weld seam 182 186 207 184 195 202 175 183 204 Q/SY 1513.2 and Q/SY-TGRC 76-2014 requirement: ≤250HV10 Fig. 4 Microstructure close to surface of pipe body Fig. 5 Banded orientation of pipe body Table 5 HIC test result Sample number Section number Average Ⅰ Ⅱ Ⅲ CLR (%) CTR (%) CSR (%) CLR (%) CTR (%) CSR (%) CLR (%) CTR (%) CSR (%) CLR (%) CTR (%) CSR (%) pipe body, centred=90°from weld seam 1 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 The SSC test result shows that the tension surface of the specimen was examined under a low-power microscope at ×10 magnification.
According to the results of microstructure observation and hardness measurement, influence of cooling rates on the microstructure and hardness in coarse grain zone of the sour service pipeline steel was studied[14-15].
Fig. 6 SH-CCT of X65MS When the cooling rate is lower than 2 °C/s, PF+P was obtained in coarse grain zone.
When the cooling rate is higher than 12 °C/s, B was obtained in coarse grain zone.

In the sintering process because of the gas phase, only a very small number of SiC molecules, so vaporization is the participation in the SiO2 lattice decomposition of SiC, In each SiC grain have a layer of oxide thin layer SiO2 .The SiO2 layer will be volatile at elevated temperatures: SiO2 (s) →SiO(g) + 1/ 2O2 (g)
Program implementation A.the choice of slurry.To improve the product density, mud density is higher, the need for reasonable particle size distribution, more important is the grain size composition should satisfy R - SiC products sintering theory demands.
Sintering mechanism follows the "evaporation - condensation," the principle, fine particles of evaporation and condensation around in the aggregate, so the ideal raw material grain size distribution is bimodal distribution.
Calculation of particle size ratio.According to the production of abrasive technology, this particle size specification is divided into two parts: (a)63 um particle size than the abrasive called "coarse grains", in the range F4-F220, the production of multi-purpose screening.
The number accounted for the volume The proportion of total volume Total volume 1 times ball E 10 4186.66 16746.66667 93.83% 17513.09 1 times ball J 4.14 297.07 297.0772589 1.66% 17956.44 1 times ball K 2.25 47.69 190.755 1.07% 17827.57 1 times ball L 1.77 23.21 278.5925059 1.56% 17858.49 1 times ball M 1.16 6.53 0 … The final choice of actual particle : Take the average sphere radius of the 2 times ball, 3 times ball, 4 times ball, 5 times ball

After it is desiccated again, it becomes firm again, this kind of characteristic can be repeated numbers of times.
It can be seen in the photo that the structure of substrate is even, the grain shape mostly appears as polyhedron.
There is no abvious appearance that the grain grows unusually, the size of the grain is even, there is no big pore, the interface among the grains is continuous widespreadly.

The results exhibit that working surfaces of both valve seat and spool are covered by a layer of continuous, homogeneous diamond films on which well-faceted diamond grains with grain size of ~2-3 μm distribute.
Both of them present similar rugged surfaces covered by a layer of continuous, homogeneous diamond films on which well-faceted diamond grains with grain size of ~2-3 μm distribute.
The slight shift to 1337cm-1 from 1332cm-1 in wave number is owing to generation of either a compressive residual stress and/or a convolution of the microcrystalline domain size [6].
The broader peak near 1580 cm-1 (G bond) can be correlated to the graphite or amorphous carbon phase existed in the grain boundary area.
The surface morphology of the as-deposited diamond films investigated by SEM exhibits that both of them present similar rugged surfaces covered by a layer of continuous, homogeneous diamond films on which well-faceted diamond grains with grain size of ~2-3 μm distribute.

Introduction In the last decade, the production of ultra-fine grained materials using the processes of severe plastic deformation (SPD) was widely established.
These techniques are capable of refining the grains to the submicrometer and nanometer scales which leads to superior properties such as high strength, good ductitlity and high superplasticity [1].
Nevertheless, processing by HPT usually produces finer grains compared to ECAP [4-6].
The total number of microhardness measurements covering the surface of each disk was 227 datum points.
It is more reasonable to specify the strain imposed during the processing by HPT in terms of the numbers of turns.

Pfeil, "Improvements in Heat Resistant Alloys," Patent Number 459,848 (1937). 2.
Rothman, "Cation grain boundary diffusion in Cr 2o3 and Cr 2o3 doped with Y 2o3," J.
Yurek, "Grain boundary segregation of yttrium in chromia scales," J.
Park, "Anion grain boundary diffusion in Cr 2o3 and Cr 2o3 doped with Y 2o3 ," presented at Materials Research Society, Reno, Nevada, 1988.

The number and chemical composition of all the 5 specimen(steel ingots)in which one is no Ce were shown in table 1.The ingots were forged into Ф26mm+2mm×700+5mm cylinder billets, experienced a 780˚C×4h annealing after the forge and made intoФ24mm×Ф12.5mm×10mm circular ring wear-resistant specimen shown in figure 1.In above forge process, the average forging ratio is 3,the begin-and final-forge temperature was 1150˚C and 870˚C respectively.
The 5# specimen contained 0.35% Ce had the biggest grain size of 6.5grade.
The 1# (without Ce)specimen and 2# (0.10%ce)specimen had the same grain size of 7grade,but the 3# (0.20%ce)and4# (0.25%ce)specimen had an obviously fined grade, but the 3# (0.02%ce)and 4# (0.25%ce)specimen had an obviously fined grain size of 8 and 7.5 grade respectively.
The 3#and 4#specimen also had a batter microstructure uniformity than 1#,2#and5#.so it could be arrived that the more Ce content is and the finer grain size is in the condition that the rare-earths addition belonged to a reasonable range, and the rare-earth element reduces the grain boundary energy and grain growth driving power, hinders the further growth of austenite grain, also makes the grain fined obviously and the microstructure more uniform.
In addition, Ce can prevent the grain boundary segregation of harmful elements so that makes the austenite grain fined sufficiently at high temperature and the fining effects of microstructure, grain more apparent at room-temperature .However, when the rare-earths addition is too lot, the rare-earth inclusions will form core granules which are taking the high melting point oxides (or sulfides)to be cores, then aggregate and grow, so that forming bigger size rare-earth inclusion in the steel.

The size of the spheroidized/recrystallized grains increased with a decreasing strain rate (Table 2).
The weak effect of deformation temperature on grain size was most likely associated with a constraint effect from the β phase (volume fraction ~ 3%), which existed in the a+b phase field in the form of thin interlayers between the α grains.
Stable fine grain size is attributed to the presence of B and Gd – rich particles (Fig. 1).
The combination of a number of factors (high deformation temperatures, small grain size, the existence of soft β phase laths limiting the α grains/particles coarsening and contributing to faster diffusion) promotes SP flow of the alloy at high strain rates.
Salishchev, Mechanical behavior of fine grained TiAl intermetallic compound-I.

Fracture strength Testing Method Fracture strength of the freestanding diamond film samples have been tested by a number of different techniques, including the hardness indentation method [9], the burst test method [9,10], the ball-on-ring method [11], and the three point bending [9-12].
However, due to nature of the columnar growth of the CVD diamond films, the grain size in the nucleation surface is much smaller than the grain size in the growth surface, and both of which are closely related to the sample thickness.
However, the reason can also be attributed to the grain size, since the grain size of the optical grade diamond films is much larger than the mechanical grade [8, 15].
However, beside the effect on grain size (or thickness), the published data is rather limited.
This is because that there is large amount of defects in the diamond films with sizes comparable to the grain size.

The grain size of powders was in the ranges from 150 meshes to 320 meshes.
They may mix unlimitedly with each other and form a solid solution named vanadium carbonitride appearing grains.
Cr3C2 and Cr3B2 mixed partly each other and posed big and round grains phase.
On account of the rapidly melting and rapidly cooling features in laser cladding, a number of carbonitrides without growing up formed fine grains uniformly distributed in the composite coatings.
However, wear mechanism of the laser cladding was obvious milling grain abrasion.