~~

~~

The solubility of Ti and C in Fe-Ti-C and Fe-Si-Ti-C melts has been determined byequilibrating the molten metal with a graphite container under CO atmosphere in thetemperature range 1400℃ to 1600℃.It has been found from the experimental datathat linear relationships exist between log N_(Ti),log N_C~(Ti)or log N_C~(Ti,Si)and 1/T,and thatN_(Ti)is not appreciably affected by the presence of 1% Si,where the N's represent thecorresponding mole fractions in C-and TiC-saturated melts.On the basis of our solu-bility data,the activity coefficient of Ti in C-free and C-and TiC-saturated iron is cal-culated and a brief discussion is made with regard to the reduction of TiO_2 in thesmelting of Ti-containing iron ore.

A new method,based on the carbothermic reduction of lime,has been devised forthe direct determination of the activity of lime in liquid blast-furnace-type slags.Thesuccess of the method depends upon the proper choice of the solvent metal to lower thechemical potential of calcium in the melt.Owing to the expected very small activity co-efficient of calcium in dilute solutions in tin,the reactionCaO(in slags)+C=Ca(in tin)+CO.has been studied with a view to evaluating activities of lime in liquid CaO-SiO_2 andCaO-Al_2O_3-SiO_2 slags.The activity values in the CaO-SiO_2 system have been used toderive silica activities through the Gibbs-Duhem relationship.The shape of the activitycurves is briefly discussed on the basis of a statistical mechanical model.It has been found from the results on the ternary system that the activity of lime isincreased by the presence of 10% alumina in the slags for the entire basicity range underinvestigation.An explanation based on the ionic constitution of slags is offered for thisbehaviour of alumina.

Homogeneous compression tests were carried out in a cam plastometer on mild steel,13% chromium steel,aluminium and lead.Aluminium and lead were tested at roomtemperatures;while mild steel and 13% chromium steel were tested at 1000,1100 and1200℃.Altogether five different rates of strain were used,ranging from 12.2 sec.~(-1)to 183 sec.~(-1),the rate of strain being kept constant during the test.With the exceptionof lead,which reached a reduction of 76%,the maximum reduction in height was 56%.During the tests,the testing temperatures were controlled accurately.The friction be-tween the specimen and the compression platens was successfully eliminated,so that testswere carried out under homogeneous compression conditions,and the true stress-straincurves corresponding to the above testing conditions were thus obtained.The experimental results show that under the above testing conditions the relation-ship between the rate of strain and the resistance to deformation for mild steel,13%chromium steel and lead obeys the following law(?)while the stress-strain curves for aluminium is practically unaffected by the change in theabove rates of strain.These experimental results have been discussed and compared withprevious work found in literature.

The optical and chemical properties as well as crystal structure of the various in-clusions in pure iron deoxidized with rare earth metals have been examined by means ofmetallographic methods and X-ray diffraction analysis.The inclusions are chiefly:CeO_2,Ce_2O_3,La_2O_3,Ce_2O_2S,La_2O_2S,CeS,LaFeO_3,FeO·La_2O_3.The process of their formation isdiscussed.

~~

The effect of thickness of specimen on the recrystallization texture of cold-rolledcopper strips under different percentage of reduction and with or without the surfacelayer has been investigated.The recrystallization texture of specimens of 0.84—0.02mmin thickness corresponding to a reduction of 88.7—99.7%,was found to have a nearlyperfect cubic texture.No concentrated cubic texture was observed in the specimens of0.01mm in thickness under a reduction of 99.8%.However,for specimens with cubi-cally aligned grains,cold-rolled to 0.01 mm in thickness(under a reduction of 98.6%),a rather concentrated cubic texture was developed after annealing at 900℃.The effect of strip thickness on the recrystallization texture has been found to bedifferent for different percentage of reduction.Under a smaller reduction of 88.7%,the specimens,less than 0.04mm in thickness,did not give a concentrated cubic texture.Whereas,for specimens under larger reduction(96—99.7%),no significant effect of stripthickness on the development of recrystallization texture was observed.The decreasing in thickness of specimens suppresses the occurrence of second re-crystallization but no pronounced effect on the grain orientation of the second recrystal-lization texture has been noticed.