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In recent years, X-ray microtomography has been developed to obtain 3D image of crack and other internal defects, such as micropore and grain boundaries, in the bulk of metal materials [5-8].
The main crack can be seen to separate into two segments in a number of regions, such as A, B and C.
Propagation of a crack may become twist from its nominal mode I growth direction due to its interaction with microstructure inhomogeneity, such as grain boundary and different grain orientation.
(a) to (b) show images corresponding to region A in Fig. 3; (c) to (d) show images corresponding to region B in Fig. 3 or grain boundaries.
By contrast, local fatigue crack growth resistance along a crack front can be evaluated by using the direct CTOD measurement method Summary Based on the investigation on 3D crack evolution process and crack opening, the following conclusions have been obtained: 1) Crack propagation retardation always occurred at a number of regions where the main crack separates into two segments.

The cold deformation elongates the grain, ruptures the grain and increases the density of crystalline defects whereas during peak aging condition, lattice coherency between matrix and precipitates records excellent property enhancement while quenching to room temperature.
Totally 25 numbers of such specimens each are prepared from the respective composite category.
Several transitional unstable secondary phases evolve along the grain boundary as well as within the grains at preferential (nucleation) sites to form stable aggregates (intermetallics) during aging [6] and critical size of that precipitate is coherent with the matrix at the interface.
A large number of changeover zones are witnessed with tremendous amount of strain field due to the spontaneous change in crystal structures during the attainment of critical size.

They identified that the network-like structure of Al12Mg17 available in base metal is converted into Al12Mg17 particles at grain boundaries.
YR=β0+l=1nβlXl+l=1nβllXl2+l=1n-1m=2nβlmXlXm+ε (2) Where YR is response, n is number of input parameters, β0, βll (l=1, 2, 3 ..
Higher the better, Di0, yj≤ymin(yj-yminymax-ymin)r, 1,yj≥ymin ymin≤yj≤ymax,r≥0 If the numbers of responses are more than one then finds the global desirability DG i.e., all individual desirability index Di are combined to form single value using the formula DG=i=1nDiri1ri, where ri is importance given to responses.
This may happen due to the change in grain size, dissolution of strengthening solutes, textural variation and presence of residual stresses [8, 16].
With increase in heat input rate, initially TS increases because it improves proper distribution of strengthening solute and grain refinement but after a certain interval it starts decreasing due to dissolution of strengthening solute as well as initiation of grain growth.

The practice shows that the ball material ratio variation has a distinct effect on the grinding energy consumption and the grain size composition.
Because of the less study on the ball material ratio in the current, the change rule of the ball material ratio on the grinding energy consumption and the grain size composition is not clear enough, the adjustment[1] of the ball material ratio is based on the production experience of the worker in the factory.
The number of different specifications steel ball is 370, the ball’s volume is 1440ml and the balls weight 11225g.
Regardless of increasing the grinding time or increasing the ball material ratio, we can extend the collision time between the ores and the mediums, so that the number of the fine fractions are increasing.
The bigger the ball material ratio is, the more the amount of fine grains is, the bigger ball material ratio is good for the grinding effect, but the ball material ratio is too big, the corresponding loading amount is too small, which result in no engineering significance in the production.

It can be noted that the grains of as-extruded Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloy are coarser with a large amount of second-phase particles observed in the grain boundary and no recrystallization occurred during or after hot extrusion.
Solution and aging treatment leads to significantly fine grains and regular distribution of second-phase particles around the grain boundary.
All tests were run to the final separation of specimen, and the corresponding cycling number was defined as the low-cycle fatigue life.
(1) Where ef¢ is the fatigue ductility coefficient, c is the fatigue ductility exponent, and 2Nf is the number of reversals to failure.

In the subsequent SR process, these alloy carbides dispersal freezing out, reinforcing the intragranular strength, and creep deformation with stress relaxation is concentrated in the HAZ coarse grain boundary.
At the same time, the sheet strips of carbides, boron, and an impurity element segregation and grain boundary, all accelerate the steel cracking along the grain boundary in the occasions of larger binding force, and it generates reheat crack in the process of heat treatment after welding. 3) Stress corrosio: The so-called stress corrosion of the metal material in some media is a delayed rupture due to the tensile stress, whose formation must contain the combinations with certain metallic structure, stress, and the medium under certain conditions.
Because of the presence of coarse grains and the inevitable impact of the residual stress due to welding joints, welded joints and adjacent base metal still have a high probability of stress corrosion crack.
Defects of TOFD test Defect Number Length (mm) Depth (mm) Height (mm) Defect category Rating S1 5 16 1.0 Slag Ⅰ S2 5.0 33.6 2.0 Slag Ⅰ S3 40 24.8 3.4 Slag Ⅰ S4 13.2 41.1 0.8 Slag Ⅰ S5 Ten (Quantity) 34.1 - Stoma Ⅰ S6 Eleven (Quantity) 19.8 - Stoma Ⅰ S7 62 18.0 1.8 Slag Ⅱ S8 22.4 21.4 3.3 Slag Ⅰ S9 19 26.2 1.9 Slag Ⅰ S1 slag S2 slag S3 slag S4 slag S5 porosities S6 porosities S7 slag S8 slag S9 slag Fig. 3.
The fluorescence method magnetic particle testing results assessment Weld Number Defect location defect magnetic marks size (mm) Rating Remark A Weld L=2 , L=3 Crack grade Ⅳ Eliminate after polishing1.5mm deep and recheck B Fusion line L=7 Crack grade Ⅳ Eliminate after polishing 0.5mm deep and recheck C Fusion line L=10 Crack grade Ⅳ Eliminate after polishing 0.5mm deep and recheck D Weld L=6 Crack grade Ⅳ Eliminate after polishing 1.0mm deep and recheck E Weld L=7 Crack grade Ⅳ Eliminate after polishing 1.0mm deep and recheck RBI of propylene spherical tank A / B The tank C inspection meets RBI inspection requirements, and test results are basically in agreement with RBI evaluation results, which validate the reliability of the conclusion risk assessment report.

For this computer model of the hot rolling process, the following technical characteristics of the QUARTO 2800 industrial rolling mill have been used and the rolling modes on it: - diameter of working rolls 725 mm; - length of body working roll 2800 mm; - diameter of rolls of edger stand 1000 mm; - speed of rolling 0.2 m/sin the first passages, further to 3 m/s; - dimensions of the initial ingot 280×1460×1700 mm, small faces are made with an angle 110°; - roll material in the model – absolutely rigid; - technological pauses between the passages from 10 to 30 seconds; - the number of final elements on which the initial ingot is divided was 100 thousand pieces and as the height of the rolled stock decreases and the length is increased, the number is brought up to 180 thousand pieces.
In the hot deformed semi-finished products near the grain boundaries, the regions free from precipitates of secondary intermetallides are observed, which are formed as a result of technological heating during annealing of ingots and subsequent hot rolling (Fig. 4, b).
Shooting in polarized light showed that the microstructure of the metal after hot rolling is characterized by a fine-grained structure (Fig. 5).
[8] Zhemchuzhnikova D., Kaibyshev R., Effect of Grain Size on Cryogenic Mechanical Properties of an Al-Mg-Sc Alloy, Advanced Materials Research. 922 (2014) 862-867
Langdon, Influence of grain size on the flow properties of an Al-Mg-Sc alloy over seven orders of magnitude of strain rate, Materials Science & Engineering.

Put forward a more complete topic heat assessment methods that take into account the number of fans of the Micro-Bo users, the number of forwarding Micro-Bo text, comments, and time factors.
Blog-text’s heat is determined by the user’s fans’ number, Blog-text’s forwarding and comments number.
At each hop forwarding number add one.
The number of forwarding can be explained the degree of concern of a blog to some extent.
Based on the number of fans, forward, and comments’ actual heat contribution rate on the Blog-text, proposed a Blog-text heat formula: (1) Where, is the heat of the i-th Blog-text, represents the number of fans of the i-th Bowen publisher, represents the i-th Blog-text forwarding number, represents the number of comments of the i-th Blog-text.

Grain size selection is based on the “friability value” and “maximum entropy” for granules in a static state.
The grain is sized and formed based on friability data and a maximum-entropy model of a static mass of granular material [4].
· After the prescribed number of revolutions, the material is cleaned from the tumbler, weighed and recorded.
Operation Manual, Document Number: VP-2017-144-U101-0077

Recent studies have shown that Severe Plastic Deformation (SPD) processes improve the mechanical properties of the parts processed, through a reduction in the grain size.
Introduction SPD processes allow us to reduce starting materials grain size down to a micrometric level or even nanometric [1].
Finally, an analysis of the accumulated damage in each ECAE passage is made with the aim of predicting the number of times the material can be processed until fracturing occurs.
The number of elements employed varies between 40000 and 70000, depending on the model.
With the number of ECAE passages, cracks will mainly appear at these zones where, in the end, this will lead the billet to fracture.