The influence of Ti on hydrogen diffusion in low carbon steel was studied by Davanathan's electrochemical method. The experimental results show that the strong trapping of hydrogen is appeared in the steel in which the Ti precipitated as dispersed TiC during aging after solution treatment. The trapping energies of the precipitation of dispered TiC are evaluated as 27.88±0.18 and about 21 kJ/mol respectively before and after the α→γ phase transformation of the steel. However, these do not coincide with the value of 94.55 kJ/mol reported by Pressouyre. The lowest apparent diffusion coefficient of hydrogen in the steel Fe-0.2Ti-0.1C is found after solution-treated at 1200℃ and aged at 550℃. It seems to be caused by the low temperature precipitate TiC with non-cubic structure and by many lattice vacancies which distort the local periodical potential fields around it.

The effect of hydrogen on the Young's modulus for β-titanium alloy Ti-15Mo was investigated by both acoustic resonance and static methods. Results show that the Young's modulus is continuously reduced by hydrogen. It seems to be not the result of hydride formation and damage caused by hydrogen charging, and the decrease of modulus induced by hydrogen and its recovery are reversible entirely. The difference of cohesive energy iamong the specimens charged with various hydrogen contents was measured by ion microprobe mass analyzer. The cohesive energy is found to be significantly lowered by dissolved hydrogen. An explanation of the experimental results may be given by the decohesion theory of hydrogen embrittlement. The Young's modulus decrease of the alloy induced by hydrogen may be attributed at least partly to the lowering of cohesive energy of the lattice, and this study may be considered as a verification of the decohesion theory.

The environmentally assisted fatigue crack growth for annealed Ti-6Al-4V alloy plates in distilled water has been studied by using fracture mechanics method. Fatigue crack growth rates da/dN were determined as a function of stress intensity factor range AK from 20 to 45 MPam~(1/2), temperature from 273 to 353K and frequency from 0.1 to 75 Hz at a load ratio of 0.11. Reference data were obtained in laboratory air at room temperature and a frequency of 10 Hz. Futhermore, SEM fractographic studies have been carried out to observe the fatigue fracture morphologies. The experimental results showed that fatigue crack growth in water is enhanced as compared with that in air. The relationship between da/dN and △K follows the Paris equation. Fatigue crack growth rates were found to decrease with increasing temperature and to increase with decreasing frequency. The temperature dependence of crack growth rate at a frequency of 10 Hz can be described as:da/dN=Ae~(Q/RT)(△K)~(2.7), where Q=6.2 kJ/mol. Fatigue fracture surface is composed of relatively flat regions and irregular fracture regions. The flat regions are covered with three kinds of fatiguestriations: ductile striations, fissure striations and brittle striations. The irregular fracture regions are heavy plastic deformation areas, combined sometimes with small areas of striations. The ductile and fissure striations show an approximate one to one correspondence with the load cycles, whereas the spacing of the brittle striations is several times larger than the corresponding macroscopic growth rate. Enhancement of fatigue crack growth by water is believed to result from embrittlement by hydrogen that is produced by the reaction of water with the crack surface of Ti alloy. The observed temperature and frequency effects on fatigue crack growth rate can be explained in terms of a strain-induced hydride mechanism. Formation of strain-induced hydride is considered to be the rate-controlling process for crack growth.

The yield strength of the pure Ti plate may be decreased at 540—650℃ for specimen containing H within the range of 60 to 80 ppm, but it is decreased no more in increasing H. The sharp upper-lower yield point is occurred on the stressstrain curve as H content less than 50 ppm at room temperature and 540℃, and disappeared as H over 50 ppm or at 650℃. Thus, the maximum interaction energy between H atom and dislocation in pure Ti was calculated to be 0.47—0.53 eV. The morphology of hydride in pure Ti was observed in the plate or needle shape. The hydride TiH_2 was found to be the structure of BCT or fcc as H content less or more than 80 ppm respectively. It is also observed under HVEM that the hydride in specimen containing 15 ppm H is of BCT structure.

The low frequency internal friction of the cold-worked Ta wire with high purity was measured before and after hydrogen charging. It showed that a precipitation peak appears at higher temperature than that of H-SK peak, and at same time the latter is decreased in its height after charging. An additional twist shows remarkable influence on the precipitation peak. Aging at the temperature in which O atoms are able to migrate to the dislocations might completely eliminate the enhancement effect. The results indicate that the hydrides might preferentially precipitate on the dislocations. The precipitation peak is considered to be associated with the interaction between the dislocations and the hydrides.

The long-range diffusion (Gorsky effect) of hydrogen in Ta has been studied as a function of temperature by means of the dynamical internal friction in the temperature range from 100—400 K. It is shown that the hydrogen diffusion coefficient, D, in 180 K>T and T>250K obeys the Arrhenius relation. The preexponential factor, D_0, and activation energy, U, have been calculated. The effects of hydrogen concentration and other impurities on the hydrogen diffusion coefficient were also discussed.

The process of tensile flake formation in super strength steel 30CrMnSiNi2A under tensile elongation at low strain rate was studied by SEM and IMMA. It is shown that the formation of tensile flake is from the dislocation transportation deduced hydrogen damage but not from the diffusion of hydrogen. The critical deformation, ε_o~c, forming tensile flake of tempered martensite or lower bainite of the steel is about 4.0 or 5.0% respectively under the same hydrogen content 5.0 cm~3/100g and same strain rate 3×10~(-5)/s. The microfeature of tensile flake is a fracture mode of quasi-cleavage with hydrogen tearing trace. A higher hydrogen content on the fracture surface of tensile flake than that of the matrix is indicated by IMMA.

SEM and optical microscope in situ examinations under tensile loading were performed on the effect of hydrogen upon the microprocess of deformation and fracture behaviour in cathodic charged pure Nb. The Nb hydrides are found to precipitate on the {100} plane of matrix. Most dendritic hydrides in orthorhombic needleshape are of the Widmanstatten structure. The slip lines and grain boundary hunches are obviously observed in the α-solid solution matrix with hydrogen dissolved under tensile deformation. The microcracks initiated themself along the slip lines predominately and the deformation bands as well as the grain boundary oriented normal to the stress axis. The main crack propagation is the coalescence of micro-craks in the vicinity of the crack tip and through the transgranular path. The α-solid solution matrix with β-hydride is extremely brittle and of transgranular cleavage fracture under tension. The micro-patterns featuring all brittle fractures and two β-hydrides are appeared on the cleavage facets. The mierocrack growth are presented at the hydride/matrix interface. The crystal orientation of hydrogen embrittlement cleavage facets in pure Nb, the stress induced β-hydride and two typical hydrogen embrittlement mechanisms of pure Nb have been also discussed.

A study on the crystallography of martensitic transformation in a Cu-26Zn-4Al alloy by means of the phenomenological crystallographic theory is presented. The habit plane of the martensite calculated by computer from W-L-R theory is found to be (17.71,9.32), through the model of B_2→modified 9R monoclinic structure, which is consistent with that of the experimental result (1,7,8) quite well.

From group theory, the irreducible representation and the 24 variants associated with the martensitic transformation of a Cu-26Zn-4Al alloy are obtained. The self-accommodating group is found to be D_(2h) and the symmetry in one and the set of self-accommodating group are analyzed.

The influence of aging at 175℃ between tension and compression upon the Bauschinger effect and variation of coercivity of dual phase steels has been investigated. The results show that the aging after tension may increase the yield strength of dual phase steel in reversal compression to the value of flow stress for strain in the original tension and occur the Lüders strain as well as dispel the prior Bauschinger effect. But it does not change the variation of coercivity with tension and compression. This implies that the aging at 175℃ after tension does not change the value of the back stress due to original tension. A measuring method of back stress was suggested and the practical importance of mentioned results has been discussed.

The permanent magnets of the nominal composition Nd_xB_yFe(100-x-y) with x=15 or 16 and y=4-10 were investigated by means of Mossbauer effect. The Mossbauer spectra may be resolved into the subspectra corresponding to the different phases. Mossbauer measurements show that the constituent phases of the alloy are varied with its B content. The α-Fe and Nd_2Fe_(17) are observed in the alloy without B; the tetragonal Nd_2Fe_(14)B occurs and Nd_2Fe_(17) disappears in that containing 4 at.-%B; the Nd-rich and B-rich phases in addition to Nd_2Fe_(14)B exist and α-Fe vanishes in that up to 7 at.-%B and the B-rich phase tends to increase predominantly while further increasing the B content. Six subspectra of the tetragonal phase correspond to the six non-equivalent Fe sites. It is pointed Out that j_2 site posseses maximum hyperfine field and also maximum quadruple splitting. The preferential occupation of j_2 site by Fe atoms is critical for establishing the high anisotropy and remanence.

With a view to evaluating the activity of CaO in the liquid system CaO-SiO_2-Al_2O_3, Sn was chosen as solvent for studying the slag-metal eqilibria. The results for 1600℃ thus obtained are believed to be more reasonable and trustworthy than previous investigations. An attempt has also been made to develop a graphical method for the analysis of data. By this means, some relatively accurate iso-activity curves of CaO have been obtained, and values of CaO activities in a wide range of composition in this melt can easily be obtained from the figures derived from experimental data by the authors. Inaddition, the amphoteric behaviour of Al_2O_3 has been determined quantitatively, and the results are believed to have practical significance in blast furnace smelting using high alumina slags.

A study has been made of the distribution of an individual trace element, namely, P, As, Ga, Ge, In, Al, Mg, Zn, Cu, Ag, Cd, Pb, Sb, Tl or Bi, between the surface film and bulk Sn metal by means of analyzing the skimmed oxide from the pure molten metal tinwhich 0.005 at.-% each of the mentioned elements was added under 310℃. The results indicated that Ga, P, Ge, Mg, Zn, Al, In or As is enriched in the surface film, and its enrichment appears to be concerned with the higher heat of formation of relative oxide. The surface oxide film was detected by X-ray diffraction as complex oxy-acid salts of SnO and oxid eof enriched element. Because of an irreversible reaction, the surface structure could be remained till solidification. The XPS research on the solidified samples revealed that the only elements, e.g. Ga, Ge, As, Al and Zn are enriched within a very thin outer layer, about 2—3 nm thick, of the surface film, as a result of the modification and stabilization of its constitution and structure. Thus the liquid Sn may be protected free from further oxidation.

The effect of the surface active elements S and Mn on the surface tension of liquid Fe was investigated by the sessile drop method and their adsorptivity on the liquid Fe surface was calculated by the Gibb's equation. In order to compare the calculated with directly measured adsorption values, the distribution of S and Mn along different depth from the surface of liquid Fe-Mn and Fe-S binary system was analysed layer by layer by AES and/or glow discharge emission spectroscopy. Results indicated that a Mndepleted zone appeared along the depth of surface layer of alloy, and it is the same to S. The higher surface active element S is found to have a greater segregation coefficient about two orders of magnitude of that of Mn. This is analogous to the previous works on calculation of adsorption values from surface tension for the Fe-Mn and Fe-S binary systems.

The corrosion fatigue (CF) and stress corrosion cracking (SCC)behaviour of steels 34CrNi3Mo and 40CrNiMo with different strength grades dealt with various tempering treatments has been investigated in artificial seawater using the fracture mechanics and electrochemical methods. Experimental results showed that the SCC susceptibility of the steel in seawater is increased and the CF crack propagation rate, da/dN, is sharply raised with the increase of its YS. For the steels of YS over 890 MPa, tempered less than 650℃, the da/dN vs △K plot appeared a plateau, in which the(dN/da)_(11) kept almost constant and its fracture surface was similar in shape to that of SCC. It is believed that the CF behaviour is close related to the SCC and the SCC Susceptibility of the steel is promoted under the CF condition.

The remelted characteristics of a 410 mm diameter consumable electrode and the Mn distribution in various regions at the electrode tip during VAR process of alloy A-286 in a 506 mm diameter water cooled crucible were studied. It was found that the Mn evaporized mainly in the forming period of droplets at the electrode tip. The Mn distributed rather homogeneously in the liquid metal film. As the remelted rate of electrodes was quite small at the end of VAR process, the Mn content of the liquid metal film seemed to be nearly that under the equilibrium conditions for the Mn evaporation reaction. The Mn content increased linearly from the liquid metal film/liquid-solid two phase region interface to the original electrode. It was suggested that the Mn evaporation is controlled by the migration rate of Mn atoms in the two phase region. The Mn content of remelted ingot, [Mn]_i, can be calculated in terms of the following equation: [Mn]_i=[Mn]_e exp (-K_1n_dγW(-1))+[Mn]_f {1-exp(-K_1n_dγ W(-1))} Obviously, [Mn]_i can be controlled by controlling the Mn content of consumable electrode, [Mn]_e, or the remelted rate, W. In addition, the composition of the condensate layer on the crucible wall has been analysed. The results indicated that the condensate layer consisted of the evaporation species Mn, Cr, Fe and Ni and it contained more than 40% of Mn. The. Mn and.Cr contents in the condensate layer were higher than those in the remelted ingot and the Fe and Ni contents in the condensate layer lower, but the Cr, Fe and Ni contents in the remelted ingots were the same as those in the consumable electrodes.

Copper K edge EXAFS spectrum of the metallic glass Cu_(70)Ti_(30) has been measured using RU-1000 rotating anode X-ray system with goniometer. Data analysis has processed based on the EXAFS analysis program package written in the authors' laboratory. The distances, coordination numbers and Debye-Waller factors between Cu atoms and neighbouring atoms are determined by fitting the experimental data with theoretical phase and backscattering amplitude. The chemical short range order and the atomic neighbouring structure feature of metallic glass Cu_(70)Ti_(30) have been discussed.

The fracture behaviour of the fused quartz particulate composites was investigated. It showed that the volume fraction of particles dispersed in the matrix leads to direct dependencies of the elastic modulus and fracture surface energy; inverse changes in bending strength as well as increasing in art exponential relation with work of fracture and thermal shock damage resistance parameter. The decohesion of the weak interface between particle and matrix may be considered as the origin of toughening.

The ratio of tube diameter to wall thickness and the relative drawing stress were believed to be the factors in wall thickness change of sinking tubes. The critical coefficient, about 3.6—7.6, obtained in both consideration of mentioned factors together is wider than that, about 5—6, conventionally used in the production practice. The effect of the process conditions, such as: properties of material, reduction in each pass, total elongating passes, lubricating conditions, drawing speed, geometric parameters of die, etc. on the wall thickness change of sinking tubes has also been investigated theoretically and experimentally. It was shown that they attributes their functions to the variation of value of relative drawing stress from which the accurate caleulational formula and plot in estimation of wall thickness change are given for industrial production.

A study was made of the kinetics of the process of catalytic carbonitriding of a steel 20 surface activated by the various additions of rare earth under different temperatures by means of thermogravimetric analysis! It showed that the co-filtration of steel surface carbonitride together with rare earth, as an active element, leads to result microalloying . The carbonitriding rate may be accelerated up to 20—25% with improved quality of concentrated case.

The difficulties of the conventional method of resolution of the physical broadening into broadening components m and n caused by the mosaic size and lattice microdistortion respectively have been discussed. With the aid of an invariable parameter K~*, the invariability of M and N related to parameters r and s respectively was found as function of K~*, thus, the invariable parameter method for calculating the mosaic size and microdistortion was proposed. This method may be not only simplified the calculation by the conventional Rezak method but also overcome the complexity of not yet solved Cauchy square and other five methods. The diagram and formula of M_1 and N_1 given as a function of K~* would ease tc resolve the physical broadening into m and n. It seems to be quite available for on-line or off-line calculation.