The study has demonstrated that the improvement of yield strength of iron-nickel-base superalloys was markedly performed by adjusting the cooling rate in the course of aging, e.g. the increase of yield strength of IA alloy uprises to 13-17 kgf/mm~2, or the relative increment of 20-25%, provided by furnace cooling instead of air cooling. Its grain boundaries are changed and the notch sensitivity is remedied. The results showed that this improvement is mainly due to full precipitation of γ＇-phase. Thus, it seems to be confirmed that an adoption of the logarithm furnace cooling may both increase the vield strength and shorten the time of heat treatment, hence, the consumption of energy and manpower can be saved as well.

Partial transformation of quenched martensite into austenite during aging in a newly developed maraging steel has been investigated by means of TEM, X-ray diffraction technique, dilatometer and high temperature microscope, etc. The mechanism of the transformation, the rule of formation, the morphology and distribution of reverted austenite and their effect on mechanical properties have been discussed.

The effect of texture on the hydrogen embrittlement directivity of cold-rolled sheets of EB26-1 high purity ferrite stainless steel and 300M super high strength steel was studied. The embrittlement was evaluated by the impact tests. The directional properties of texture in specimens were examined by inverse-pole-figure method. And the morphology of surface and fracture of impact specimens was observed by SEM. It was found that the hydrogen embrittlement of cold-rolled sheet is markedly directional. The susceptibility in charged parallel to the rolled direction of sheet is the highest, while in perpendicular, is the lowest. The directivity of hydrogen embrittlement may be satisfactorily interpreted by the model of dislocation short-circuiting-diffusion paths of hydrogen. Let the texture parameter, [P]_E=P_(110) +P_(211)+1/2(P_(110)+P_(321)), denote the distributive probability of dislocation lines normal to the surface. [P]_E seems to be closely related to the susceptibility of hydrogen embrittlement under condition of equal dislocation density. It has been confirmed by the experimental results of 300M steel sheet. Thus, the value [P]_E is one of the controlling factrs for hydrogen embrittlement.

The evaporating rates of alloy elements from melts of Nb, Nb-W or Nb-W-Zr alloy at 3000-3600℃ have been examined by“melting ingot block”method. The activation energy of evaporation of Nb from Nb-W-Zr melt was obtained to be 175.9 kcal/mol. The rate-controlling step of the evaporation of Nb from Nb-W or Nb-W-Zr alloy is the detachment of Nb atoms from the liquid alloy surface, whereas the evaporation of Zr from Nb-W-Zr alloy seems to be a complex process. The evaporating rate of W from both Nb-W and Nb-W-Zr alloys, however, is controlled mainly by diffusion. The distribution of the alloy elements in the surface diffusion layer of quenched alloy melts has been determined by EPMA. It is measured that the thickness of diffusion boundary layer of Zr in liquid Nb-W-Zr alloy is 5.5—13.5×10~(-4)cm at 3080℃, and the concentration of Zr at surface is about 20% of that in bulk; the thickness of W diffusiin boundary layer is about 7—10×10~(-4) and 4—10×10~(-4)cm at 3120 and 3080℃ respectively, and the Wconcentration at surface is only 10% of that in bulk. A tentative estimation has also been made on the activity of coefficient of Nb or Zr. At 3000—3280℃ the activity of Nb in the Nb-W alloy is roughly equal to l. However, in the case of Nb-W-Zr alloy the Nb activity is much smaller, being 0.24 at 3600℃ and 0.17 at 3350℃. The apparent activity coefficient of Zr in Nb-W-Zr alloy is 0.16—0.31 at 3350℃ and 0.16—0.22 at 3600℃.

A SEM investigation has been made of the occurrence of the dark facet fracture in Al deoxidized cast steel 30MnNiMoCu using dispersive spectrometers of X-ray wave and energy. It was found that the AIN precipitation in the interdendritic areas along the original as-casted columnar grain boundaries contributes mainly to this kind of fracture. The solution and precipitation behaviour of AIN as well as the dependence of AIN on the amounts of Al and Ti added have also been discussed quantitatively.

An attempt was made to understand the behaviour of Al and N, and to determine the mutual proper range of them contained in the grain oriented silicon steel. It has been shown that its magnetic properties is affected by the formation of AIN as effective inhibitor in which the N content seems to play an important role. The N both contained in solid solution and combined in AIN were determined by hydrogen extracting method. Finally, its technological feature influenced mainly by such AIN inhibitor has been discussed.

The division of stress on the yield locus in metal forming processes of plane stress is presented. The tendency of variation of three orthogonal size of workpiece is illustrated in Fig. l. It is assumed that. unrolling the Mises circular cylinder to a plane is a convenient method, and σ_m-θ stress plane is given first(σ_m-mean stress,θ—characterized strain angle). And the equations of interface between various regions are also given. Finally, the location of typical metal forming processes in stress plane has been illustrated in Fig.5 from which the tendency of variation of three orthogonal size may be judged and the resistance and plasticity of metal forming processes may also be compared.

A discussion has been made of the possible ordering structure in type A-15 compound Nb_3(Al_(0.75 Ge_(0.25))given previously by Kitchingman et al. The correct X-ray structure factors for several possible ordering structures of this compound are suggested and it is pointed out that the conclusion drawn by Kitchingman etal. seems to be doubtful.

The valence electron structure ofε-Fe_3C was studied on the basis of recently published Yu’s“empirical electron theory of solids and molecules”and corresponding known crystallographic data. It seems that the discussion about both the analysis of the bond length differences and the magnetic moment of atoms may warrant such conclusions:(1)The Fe and C atoms inε-Fe_3C are of step A-11 and 6 respectively;(2)There exist n_(A(Fe-C))bond and n_A=0.8440;(3)The space distribution of n_A bonds forms regularly a 3-dimension network structure. It is estimated that this is the structure of higher mechanical strength and low-temperature stability;(4)Although the mechanical strength and hardness ofε-Fe_3C may be inferior to that of cementite Fe_3C, yet the former will be not so brittle as the latter owing to their more regular space distribution of n_A bonds.

A polythermal phase diagram study has been made of the Al-rich part in the AI-Si-Ge system by the methods of thermal analysis and metallography. The system belongs in a eutectic type with continuous transition from one binary side to the another. The temperatures of the eutectic line gradually decrease from 577℃ on the Al-Si side to 423℃ on the Al-Ge side. The orthogonally projected eutectic line is slightly convex to the Al-corner from the connected line of two eutectics on the both binary sides. No evidence was found about any new compound and phase in the system.

The viscosity of 24 melts of different composition, containing not less than 60% CaF_2 and not more than 40%(CaO+La_2O_3), has been determined, and the phase characteristics of these melts under different solidification regimes has been investigated by petrography, EPMA and X-ray structural analysis. A model of the structure of these liquid melts may be suggested. A low viscosity region is obtained after the iso-viscosity diagrams at 1550,1530 and 1500℃ are constructed.

The flowsheet to float spodumene in alkaline medium without desliming has long since been borne out by its simplicity, low cost and easy supply of reagents. It was ensured in industrial practice that the spodumene concentrate with a grade of 6.0-6.1% Li_2O and recovery of 88-90% may be produced from ore containing 1.2-1.3% Li_2O. Several trials have been made to troubleshoot for separation of spodumene from the froth together with beryl such as:1050℃ decrepitating-sizing;600℃ roasting-flotation;85℃ digesting-flotation as well as flotation at room tem-perature. Among these the satisfactory results were obtained, and some of them were brought into operation in mills. Especially, the separation of beryl from spod-umene by flotation with“mixed reagent”(FeCl_3+Na_3SiO_3)add edto Na_2CO_3, Na_2S, oxidized paraffin soap at room temperature was a great success. Hence, the flowsheet of cleaning separation and bulk flotation of beryl-spodumene is developed providing a new way for recovery and separation of oughing froth containing these two minerals.

The forming conditions and characteristics of{100}etch figures appeared in the typical planes(h00),(hk0)and(hkl)of metals with cubic lattices were discussed in detail. Based on the discussed results, the criterions for the variety of etch pits with the same crystalline parameters were given, according to which the origin of variety of etch figures was shown as the natural results of their forming conditions, mainly, the ratio of attacked speeds between the sample and facets of etch pits C=v_0/v, where v_0 and v is the attacked speed of specimen surface and etch pit facets, respectively. The experiments showed that v_0=const. during etching process, but v decreases deceleratively. It has been found that for rectangular etch pits appeared in(hk0)plane, the critical values are C_1=(cosω-sinω)and C_2=(cosω+sinω), where ω-angle between(hk0)and(010). If v_0/vC_2, then there is no any pit can be formed on the specimen surface. For triangular etch pits appeared in(hkl)planes the critical values are: C_1=(1-l)(h+k+l)/(h~2+k~2+L~2)~(1/2), C_2=(1-k)(h+k+L)/(h~2+k~2+l~2)~(1/2), C_3=(1-h)(h+k+l)/(h~2+k~2+l~2)~(1/2) and C_4= (h+k+l)/(h~2+k~2+l~2)~(1/2), while v_0/vC_4, then there is no pit can be formed on the specimen surface. A graphical method for determining the referred cube and the variation of corresponding etch pits on given(hkl)plane was proposed.

The impact toughness, low frequency internal friction and TEM examination were tested for steels 40Mn2, 40Mn2Mo and 30CrMnSiNi2. Experimental results indicate that the appearance of high temperature temper brittleness in these steels seems to be always accompanied by the decrease of Koster peak heights. The mechanism of this phenomenon may be explained as the result of an aging process of α-α-solid solution with precipitation of Fe_3C(N)particles causing pinning of dislocations and thereby decreasing the impact toughness.

For the purpose of the residual stress determination of the materials with coarser grains such as most of Al alloys and Ni-base alloys using X-ray oscillation method, the formulae for the stress calculation have been proposed. It was resulted that the calculated values obtained are fairly consistent with those by conventional X-ray stress measuring methob of fixed ψ_0 angle.

A mathematical equation described the metal deformation zone in the piercing process on Mannesmann two rolls mill has been derived. It was evidenced that the rolling-pass of the Mannesmann rolls is non-linear and the non-linear barrel-shaped rolls are unfavourable for further increasing the production capacity with high effeciency and improving the tube quality. Therefore, they should be replaced by a roller configuration with cross or compound curve. The confirmation of the aforementioned results was achieved by industrial practice.

A study was conducted to obtain a better understanding of carbide precipitation occurring in a cold-rolled commercial 3%Si-Fe sheet after 900℃ 1 h solid solution treatment by TEM observation. It was shown that under different aging conditions two carbides, namely ε-carbide and cementite Fe_3C, may be precipitated by either intragranular or intergranular mode. While the orientation of the intergranular precipitation of Fe_3C under elevated temperature seems to be a Bagaryatskii’s relatioship between itself and one of the matrix grains.

A formula for calculation of the possible wt-% content of γ＇-phase, G(γ＇), formed in the precipitation hardening nickel-base superalloys was derived as: G(γ＇)=6.662C_(al)+4.256C(Ti)+2.896C_(Nb)+2.153C_V+1.973C_(Ta) +0.905C_W+0.393C_(Mo)+0.121C_(Cr)+0.001C_(Co) where C with sub-symbol of an alloying element is its own wt-% contained in such superalloy. The calculation for 25 commercial nickel-base superalloys was made by this formula with satisfactory results.

For a charged type Ⅲ cracked or notched specimens of ultra-high strength steels, the hydrogen induced delayed cracking(HIDC)could occur along the planes inclined 3π/4 to a plane normal to the torsion axis. No delayed cracking and failure occurred in a uncharged or outgased type Ⅲ specimen and a flat shear fracture would be obtained on the plane normal to the torsion axis. The calculation shows that the interaction energy between shear stress field of tye type Ⅲ crack and the strain field of an interstitial hydrogen atom has a minimum value on the planes inclined 3π/4 to the plane normal to the torsion axis. Hence, atomic hydrogen will diffuse to and be enriched in these planes and HIDC will occur along these planes.