Search results

It was found that the grain becomes coarse suddenly when the temperature exceeds 623 K.
The grain diameters of FD materials were smaller than those of NR materials and their difference became larger at high temperature because of the grain growth being restricted by the chip interface.
Numbers in the sample names mean the rolling temperature. 330 340 350 360 370500 550 600 650 700 Rolling temperature (K) Tensile strength (MPa). 14 17 20 23 26 Elongation (%).
NR(10%DSR) FD(10%DSR) 6 8 10 12 20 25 30 35 40 Grain diameter (mm) Weight loss (%) .
The weight reduction rates determined in the immersion corrosion test versus the grain diameters.

Recent studies show that Sr addition in magnesium alloy has very good grain refinement effect, moreover, compounds of Al-Sr and Mg-Sr precipitating in matrix, which has high melting points and therefore do not decompose, can impede grain boundary slipping and consequently improve mechanical properties at high temperature [6,7].
Table1 Chemical composition of alloys Alloy Number Analyzed component （wt%） Designed component (wt%) Al Sr Mg Al Sr Mg 1# 6.023 0 Bal. 6.0 0 Bal. 2# 6.006 1.896 Bal. 6.0 2.0 Bal. 3# 5.994 3.743 Bal. 6.0 4.0 Bal. 4# 5.934 5.560 Bal. 6.0 6.0 Bal.
When the content of strontium was zero, 1# alloy was composed of mainly island-shaped α-Mg matrix ( including the primary α-Mg and eutectic α-Mg ) and β-Mg17Al12 phases of divorced eutectic precipitation.β-Mg17Al12 phases were mainly distributed in grain boundary, with a small amount in the grains.
Clearly, in this experimental condition, with increasing Sr addition the number of free-state Sr in magnesium alloy melt increased so that grains of magnesium alloy became smaller.
Strontium element brought about grain refinement and increased grain boundaries, which was helpful to hinder dislocation moving during deformation.

The cost-affordable HDH Ti powder has been used for commercial production of a number of PM Ti parts.
A small addition of Si has been used in a number of commercial Ti alloys by the ingot metallurgy approach to improve their resistance to creep and oxidation.
An effective way of refining the β grains is to introduce stable β grain growth inhibitors at the sintering temperature.
As a result, TiB has the potential to first nucleate β grains and then inhibit β grain growth.
Alloying with iron and silicon has shown some good potential but it is necessary to control the grain size through the use of both grain nucleants (for both β and a) and grain growth inhibitors (for β grains).

It describes how the severity of the corrosion was the result of interaction of a number of factors, and outlines the measures taken to alleviate the problems.
The Fig. 2a shows that the grains have clean grain boundaries, without intermetallic phases.
But no enough grain growth has occurred to suspect overheating.
Here too, discrete precipitates have formed along the grain boundaries.
In the first case, the grains had clean grain boundaries, without intermetallic phases, indicating that the temperature has been above the maximum temperature stated by the customer (900°C).

In addition, the ratio between fatigue limit and hardness number becomes considerably smaller than that of conventional structural steels.
The tensile strength is decided by the average strength of the grains; on the other hand, the fatigue limit depends on the microscopic strength of the weakest grains.
With the increase of the number of cycles, the specimen reaches to catastrophically fracture.
Although the in average hardness numbers are different, the hardness numbers of the weakest part of the two materials (ferrite part) are almost the same.
The tensile strength is decided by the average strength of the grains; on the other hand, the fatigue limit depends on the microscopic strength of the weakest grains

Viewing it in one scale level it can be considered as a set of grains on the surface of failure.
The grains can be of a random shape.
Every coherent destruction of each grain will have its emission of corresponding AE impulse.
Each impulse will have individual properties reflecting grain’s individual shape and size.
It still used by small number of people and wide sphere for scientific researches.

With the recrystallization and grain growth of deformed samples, PTF decreased to be about 30%.
The ingot was forged and heat-treated to improve grain uniformity before rolling.
A large number of dislocations and internal stress generated, at the same time distortion energy increased during this process [12].
While the annealing time was extended to 120 minutes, as shown in Fig. 4 (e), new grains without distortion form and recrystallization completed.
Additionally, the annealing time continued to increase to 180 minutes, recrystallized grains grew up.

The present work deals with APS deposited Inconel 625 structures consisting of huge number of individual splats formed by impacting molten droplets on substrates during spraying process.
The grain growth occurs in the direction of heat transfer into the previous splats.
Some equiaxed grains also can be recognized inside the splats.
Few numbers of splats in the size ranges from 45-110 µm were collected onto the stainless steel substrates with shiny surface to evaluate the morphology distribution of splats.
The grain growth occurs in the direction of heat transfer; both equiaxed and columnar grains are visible in the microstructure. 2.

In order to preserve charge neutrality, the dominant Cu2+ will increase the number of Mn4+ (0.53 Å) ions which has the smallest ionic radius compared to other B-site ions [13].
Therefore, it is expected that the increase in Mn4+ number which is caused by the copper substitution will decrease the unit cell volume of the sample.
This suggests that each grain observed from micrographical approach consists of several smaller crystallized grains [12].
This suggests that copper substitution affects the transport properties at grain boundary.
Thus, one can conclude that ρ0 also has a correlation with the grain size of the material.

The study has established that grain refinement is observed with increasing nitrogen content in steel.
Introduction of boron, in absence of titanium, does not change the size of the austenite grain in the entire range of the investigated temperatures.
Boron tends to segregate along the boundaries of austenite grains [9, 10], reducing their energy.
Influence of microalloying on actual austenite grain of 40GF-VI (vacuum-induction) Heat No.
It has been established that grain refinement is observed with increasing nitrogen content in steel.