摘要:

Experiments into the swelling and foaming of synthetic iron oxide gangue melts prove that two basic prerequisites have to be met for the occurrence of these phenomena. Firstly there must be present within the specimens relatively large volume fractions of a liquid FeO‐containing phase which come into contact with carbon. This leads to heavy gas formation. Secondly, slags of this type must exhibit a certain gas retention capability. In this respect, a precipitated iron support skeleton can be helpful. Medium‐basic slags swell very well and over a relatively long period. Highly basic slag melts, following a brief period of swelling, are quickly resolidified by 2CaO‐SiO2precipitation. In the case of acidic specimens, only a small or no volume increase is observed. Pure iron oxide melts undergo virtually no swelling whatsoever.

ISSN:0003-8962    

DOI:10.1002/srin.199301559

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The reduction rate of Mo oxide in slag by iron‐carbon melt under different stirring conditions, reaction temperatures and slag composition has been investigated. Results indicate that the reduction of Mo oxide is a fast reaction; both stirring and temperature have evident influence upon the reaction; while the initial concentration of Mo oxide and content of fluoride in slag have also some influence upon the reaction. The reduction of Mo oxide is an apparent first order reaction. At 1440–1500°C, the reduction rate of Mo oxide is mainly controlled by Mo transfer in slag, with its diffusion activation energy of 223 kJ/mol. At 1500–1590°C, the transfer of Mo in metal turns to be the main limiting step, with its diffusion activation energy of 81.5 kJ/mol.

ISSN:0003-8962    

DOI:10.1002/srin.199301560

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The measuring method proposed by Keene and Quinn has been further developed to investigate 3‐component slags of the system CaO‐SiO2‐Al2O3at temperatures of 800–1600°C in the wavelength range of 550 to 850 nm. The results are presented with the aid of the complex refraction index, which embodies all information on the optical properties of the slags investigated, including photon conductivity and thermal emissivity. Comparison of the photon conductivities determined shows good agreement with the corresponding values of various types of glass cited in literature. The discontinuous pattern of the phonon conductivity curve in the melting range of 40% CaO‐40% SiO2‐20% Al2O3slag, as already found by Gammal and Li, is also evident from the data of the present investigation.

ISSN:0003-8962    

DOI:10.1002/srin.199301558

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The redundant shear strains of the three‐roll combined piercing‐elongating seamless tubemaking process are qualitatively analysed by two kinds of simulative workpieces made of pure lead. The distribution of the three redundant strains along deformation zone and relationship between total redundant factor and feed angle are obtained under the condition of different process parameters, which provide the reliable basis for reasonable design of deforming tool and optimization of process parameters.

ISSN:0003-8962    

DOI:10.1002/srin.199301561

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

It is known that austenite strength determines the morphology of the new phase during martensitic transformation. As the strength of austenite influences the growth of a martensite crystal, i.e. the movement of the austenite/martensite interface, a correlation between strength of the parent phase andMshas to exist.Msdepends on thermodynamical and mechanical properties of the alloys. To distinguish the individual variables, austenite strength was changed by different hardening mechanisms: solid solution hardening, plastic deformation or both.

ISSN:0003-8962    

DOI:10.1002/srin.199301562

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The tempering behaviour of a dual phase steel of 0.08% C, 1.21% Mn, 1.00% Si, 0.42% Cr, and 0.41% Mo composition with two different martensite contents of 30 and 52%. (obtained by intercritical treatments at 820 and 860°C, respectively) has been studied. The ultimate tensile strength decreased and percentage elongation increased continuously with increasing tempering temperature up to 600°C for both intercritical treatments. The yield strength has, however, increased up to 300°C, beyond which it decreased for the steel with 30% martensite. In contrast it remained almost constant for 52% martensite up to 300°C, beyond which it decreased. The martensite of dual‐phase steel for both the intercritical treatments has undergone microstructural changes on tempering that are akin to those of fully martensitic low carbon steels. The SEM fractographs from the as‐quenched specimens indicate that the tensile specimens failed by microvoid coalescence with the martensite areas appearing facetted and featureless while those for 600°C tempered condition by the formation of equiaxed dimples.

ISSN:0003-8962    

DOI:10.1002/srin.199301563

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

The effects of additions of 0.6 to 2.0% Cr on the temper embrittlement behaviour of 0.25 C–1.0 Si–1.3 Mn cast steel under several hardening conditions were studied. The susceptibility to temper embrittlement, transgranular and intergranular fracture were increased as the chromium content increased when the steels were tempered at 350°C and slowly cooled from 550°C. The impact toughness and abrasion resistance of the steels were found to depend to a great extent on the Cr‐content and tempering temperature.

ISSN:0003-8962    

DOI:10.1002/srin.199301564

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

High‐strength tensile bolts of class 8.8 were produced without final heat treatment. Shank‐threaded bolts with shanks larger than 65 mm showed inadmissibly large elongations after being tested in proof‐load tensile tests according to DIN‐ISO 898‐1. The reason could be plastic compression applied during fabrication in combination with tensile stresses during testing (Bauschinger effect). For a better understanding of this phenomenon different types of steel were tested in combined compression‐tension tests. It was discovered that plastic compression of 1–1.5 % can lead to a maximum decrease in yield strength of 50%. The mathematical relation between decrease and compression rate can be described by a simple power law. As a consequence bolts of this size need an additional heat treatment. In case of being integrated in some other part of production no additional costs occur. Wholly threaded bolts and shank‐threaded bolts with shanks smaller than 65 mm can be used without final heat treatment.

ISSN:0003-8962    

DOI:10.1002/srin.199301565

出版商:Wiley    

年代:2016

数据来源: WILEY

摘要:

Unexpected failures of 18/10 CrNi and 17/12/2 CrNiMo steels in indoor swimming pool atmospheres made it necessary to reinvestigate chloride stress corrosion cracking of stainless steels with respect to their use in arcitecture. A preceding paper presented inwestigations into stress corrosion cracking (SCC) in the active state of corrosion; the present paper deals with SCC In the passive state. The investigations showed that – in contrast to general opinion – stress corrosion cracking in the passive state can occur at temperatures well below 50°C in 18/10 CrNi and 17/12/2 CrNiMo steels, provided the corrosive medium has an extremely high chloride concentration. Other factors such as stress level, pH value or type of kation only exert a subordinate influence. Especially the high alloy austenitic steels 1.4439 and 1.4539 proved SCC‐resistant under such conditions at ambient temperatures.Electrolytes with critical chloride concentrations may develop when deposits containing chlorides of sufficiently high solubility (e.g. MgCI2, CaCl2) are exposed to an atmoshere with critical, i.e. comparatively low humidity. Such conditions are evidently met only under very specific circumstances such as may occur in indoor swimming pools. In other structures where stainless steels have been used for decades without such damage having occurred to date, these critical conditions appear generally not to be reached.

ISSN:0003-8962    

DOI:10.1002/srin.199301566

出版商:Wiley    

年代:2016

数据来源: WILEY

ISSN:0003-8962    

DOI:10.1002/srin.199301567

出版商:Wiley    

年代:2016

数据来源: WILEY