Interrelation of CCM (Steel Billet Continuous Casting Machine) Tube Steel Casting Parameters and Hot-Rolled Plate Quality

The quality of the hot-rolled plate up to 36 mm thick was estimated by the percentage of rolled products, sorted due to the presence of a surface defect "Non-metallic inclusions", and internal defects, detected by ultrasonic plate control. The analysis of the data on the total sorting of hot-rolled plates demonstrated that the amount of sorting differs significantly on the melting from which each series of tubular metal casting commenced, compared to all the other melting in the series. The sorting of the sheets rolled from the metal of the first in a series of melting proved to be 1.9 times higher than that of the metal of all other melts. The main reason (in 68% of cases) of sorting is the presence of non-metallic inclusions on the surface of the plates. The effect of sorting of hot-rolled plates on non-metallic inclusions of various parameters has been studied: the duration of the intermediate ladle-heating; the length of time from the end of the heating of the intermediate ladle, prior to the beginning of the casting; lining temperatures of the intermediate ladle before the beginning of casting; duration of filling the intermediate ladle; the filling rate of the intermediate ladle with metal; mass of metal in the intermediate ladle before the beginning of casting into the crystallizer; chemical composition of metal; overheating of the metal over the liquidus point at the beginning, middle and end of the casting. On the sorting of flat products for non-metallic inclusions, of all the parameters considered, a statistically significant effect is due only to the overheating of the metal above the liquidus point, which varies in the range from 19 to 35 ° C. In order to obtain an acceptable quality of both the surface of slabs and the surface of hot-rolled plates for non-metallic inclusions, the first in a series of melts recommends overheating of the metal in the intermediate ladle above the liquidus temperature of 30-35 ° C.

An inter-comparison of isotopic composition of neon via chemical assays and thermal analyses (IUPAC Technical Report)

In 2003–2014, a study on the effect of isotopic composition on the triple point temperature of neon was conducted under the framework of a Project involving laboratories from 11 countries. Natural neon from commercial sources of different isotopic composition, high-purity 20Ne and 22Ne isotopes, and certified artificial isotopic mixtures were used. The thermometric studies comprised: a) a total of 131 analytical assays from 3 laboratories on the isotopic composition of samples taken from 31 different bottles of neon with chemical gas purity 99.99 mol % to 99.9995+ mol %, including chemical impurities for some samples, with up to 12 assays per sample; b) multi-laboratory thermal analyses, with accuracies ranging up to better than 50 μK (k≈2), on 39 samples, almost all permanently sealed in metal cells, for the determination of the liquidus-point temperature of the triple point as a function of isotopic composition. The thermometric studies also constitute an international inter-comparison of thermal and analytical assays on the isotopic composition—and occasionally of the chemical impurities—of neon. These tests are critically needed for top-accuracy thermometry. The main results of the inter-comparison of the various chemical assays, and of the comparisons between the assays and the results of thermal analyses, are reported. They show discrepancies in x(20,21,22Ne), especially for x(22Ne), in ‘natural’ neon, for the same gas bottle, equivalent to an uncertainty of up to 165 μK (k = 1) in the triple point temperature, as measured by all testing laboratories, and of about 100 μK (k = 1) as measured from a single testing laboratory. This is an unsatisfactory situation for thermometry, since it is difficult to obtain a reliable and accurate isotopic assay for neon, thus limiting the accuracy of the realisation of the neon triple point temperature as a ITS-90 reference point to well above 50 μK. However, it also discloses a strong limitation in the relevant analytical chemistry.

The freezing points of high-purity metals as precision temperature standards. VIIIb. Sb: Liquidus points and alloy melting ranges of seven samples of high-purity antimony; temperature-scale realization and reliability in the range 0–631 °C

An investigation was made of the freezing and melting temperatures of seven samples of high-purity antimony, five with analyzed impurity contents ranging from <0.3 to <0.7 p.p.m. (wt.) and two with impurity contents of ~10 and ~100 p.p.m. (wt.) respectively. The Sb melts had to be deoxidized in situ to eliminate the effect of dissolved oxygen (gaseous or oxide form), which was found to cause large depressions and instabilities in the liquidus-point temperatures. A variation of 0.0026 °C in liquidus point was found among the five purest samples, but the standard deviation for a single determination of the liquidus point realized on outside-nucleated slow induced freezes (ONSIF) of any given sample was [Formula: see text]. The best Sb samples had nonequilibrium alloy melting ranges of a few centidegrees which are distinctly inferior to melting ranges of only a few millidegrees found on samples of Sn, Zn, and Pb with similar analyzed impurity contents: the inferiority is attributed to residual impurity effects in the Sb samples and not to either lag in detector response or anomalous molecular effects in the melting Sb. A value of 630.553 (°C Int./60) was determined for the liquidus point at standard pressure of the purest NRC Sb sample.After establishing the Sb point, eight silica-sheathed standard resistance thermometers were intercompared at the ice, Sn, Cd, Zn, and Sb points to provide information at the highest precision on stabilities of fixed-point realizations and resistance thermometers, inter-thermometer variations, advantages of particular quadratic resistance–temperature interpolation relations, preferred calibrating procedures and thermometer handling techniques, and temperature-scale stability and reliability over the full range 0–631 °C.

The freezing points of high-purity metals as precision temperature standards. VIIIa. Sb: Apparatus, freezing techniques, and ingot morphology

This paper describes the apparatus and the freezing techniques that have been developed to determine the liquidus points (630.55 °C) of samples of high-purity antimony to a reproducible precision of ± < 0.0005 °C. Freezing plateaux steady to ± 0.0001 °C for long (hours) durations are readily obtained on freezing curves of high-purity antimony using an outside-nucleated slow induced freezing (ONSIF) technique in a balanced three-winding inconel block furnace. The pressure effect on the freezing temperature of antimony was determined as + 0.000 85 °C for 1 atm, which corresponds to a contraction on Sb solidification of 0.98%; a contraction on freezing is supported by volumetric measurements on the shrinkage pipes in Sb ingots and by observations on decanted and quenched (during freezing) ingots that Sb dendritic solid is more dense than Sb liquid.Metallurgical studies using decanting, quenching, and tracer techniques determined the ingot morphology during freezing and melting to verify that a satisfactory control of the transforming ingot had been attained for liquidus point realizations and to provide auxiliary information on the nature of solute segregation and segregate remelting for the interpretation of alloy melting-range comparisons on several samples of high-purity antimony described in Part VIIIb of this series of papers. Abundant evidence of the fragmentation of masses of large rod dendrites and the surface recontouring of dendrite spines by recalescent remelting was found in both decanted and quenched Sb ingots: the pileup of dendritic solid in the bottom of the crucible does not preclude precise temperature determinations on ONSIF freezes.

THE FREEZING POINTS OF HIGH-PURITY METALS AS PRECISION TEMPERATURE STANDARDS: VII. THERMAL ANALYSES ON SEVEN SAMPLES OF BISMUTH WITH PURITIES GREATER THAN 99.999 + %

An investigation has been made of the freezing and melting temperatures of seven samples of high-purity bismuth (analyzed impurity contents <0.5 to 7 ppm) including zone-refined metal. Using a controlled outside nucleation technique, freezing curves having plateaux of essentially constant (< ±0.0001 °C) temperature with long durations are readily obtained. A standard deviation in plateau temperature (liquidus point) of ±0.00025 °C was obtained from a series of 34 freezes on a particular sample. The pressure effect on the freezing temperature of bismuth was determined as −0.0035 °C for 1 atmosphere. A value of 271.375 °C (Int. 1948) was determined for the standard liquidus point of pure bismuth.The liquidus points of the samples were intercompared with a precision of about 0.0002 °C and their alloy melting ranges were measured for selection of the purest samples. Ingot morphologies and solute redistributions during melting and freezing were investigated using decanting, quenching, and tracer techniques.Appendix I gives the results of the latest intercomparison of temperatures realized in a grid of water triple-point cells that is maintained by this laboratory for use in the precision temperature measurements. Appendix II lists the values and pressure–temperature dependencies of the liquidus points of the purest samples of Zn, Pb, Cd, Bi, Sn, and In that have been determined at this laboratory.

THE FREEZING POINTS OF HIGH PURITY METALS AS PRECISION TEMPERATURE STANDARDS: VI. THERMAL ANALYSES ON FIVE SAMPLES OF LEAD WITH PURITIES GREATER THAN 99.999+%

An investigation has been made of the freezing and melting temperatures of five samples of high purity lead (supplier's analyzed impurity contents < 0.7 to < 4 p.p.m.) including zone refined metal. Using the induced freezing technique, plateaux of essentially constant (< ±0.0001 °C) temperature with durations of over 1 hour are readily obtained on the cooling curves of these samples. A standard deviation in plateau temperature (liquidus point) of ±0.0001 °C was obtained from a series of 30 induced freezes on a particular sample. The pressure effect on the freezing temperature of lead was found to be 0.0080 °C for 1 atmosphere. A value of 327.426 °C (Int. 1948) was determined for the standard liquidus point of pure lead.The liquidus points of the samples were intercompared with a precision of about 0.0002 °C, and alloy melting ranges were examined following different types of freezing with and without overnight anneals near the solidus temperature. Alloy melting range parameters were found to be useful in the selection of the samples of highest purity and at the same time showed that an uncertainty of 0.002 °C in the above value of the liquidus point of pure lead may exist because of residual impurity contents in the purest samples that were examined.

THE FREEZING POINTS OF HIGH PURITY METALS AS PRECISION TEMPERATURE STANDARDS:V. THERMAL ANALYSES ON 10 SAMPLES OF TIN WITH PURITIES GREATER THAN 99.99+%

Extensive thermal analyses have been made on 10 samples (suppliers' analyzed impurity contents <0.2 to <100 p.p.m.) of high purity tin, including zone-refined metal; liquidus points have been intercompared with a precision of about 0.0002 °C and alloy melting ranges have been examined following different types of freezing with and without overnight anneals near the solidus temperature. Samples of nominal 99.9999% purity tin were found to have such narrow alloy melting ranges that any ambiguity, arising from unknown impurity concentrations, in specifying the liquidus point of pure tin is well inside 0.001 °C; a value of 231.913 °C (Int. 1948) was found for the standard liquidus point of pure tin. An account is given of the supercooling that was observed on the bulk samples and of anomalous structures that were found on melting curves. An appendix gives the results of long-term intercomparisons of the temperatures realized in four water triple point cells.

INTERCOMPARISON OF 11 RESISTANCE THERMOMETERS AT THE ICE, STEAM, TIN, CADMIUM, AND ZINC POINTS

Eleven standard platinum resistance thermometers, including thermometers having three different types of construction, have been intercompared at the triple point of water, boiling point of water, and the liquidus points of high purity tin, cadmium, and zinc. Temperature coefficients determined from measurements at the triple and boiling points of water and the zinc point were used to calibrate the thermometers for the temperature calculations on measurements at the tin and cadmium points. The results show that, although the measurements were made at a precision of about 0.0002 °C at each fixed point, distinctive deviations from quadratic resistance–temperature relations were not found for the 11 thermometers. This verification of the quadratic form for the resistance–temperature relationship realized with these thermometers gives strong support for the use of the liquidus point of high purity indium, tin, or cadmium as a precision alternative to the steam point on the International Temperature Scale.

THE FREEZING POINTS OF HIGH PURITY METALS AS PRECISION TEMPERATURE STANDARDS: IV. INDIUM: THERMAL ANALYSES ON THREE GRADES OF CADMIUM

An investigation of the freezing and melting temperatures of a sample of high purity indium (Cominco 99.999+ %) has been made. Plateaux of essentially constant (< ± 0.0001 °C) temperature with durations for over 1 hour are readily obtained on the cooling curves of induced freezes on this metal. The standard deviation of the plateau temperature (liquidus point) from a series of 24 induced freezes was ±0.0001 °C. The pressure effect on the freezing temperature of indium was found to be 0.0049 °C for 1 atm. Alloy melting ranges were measured following different types of freezing.An extensive intercomparison of liquidus points and alloy melting ranges has been made on a sample of 99.99% cadmium and two samples of 99.999+ % cadmium from different suppliers. The liquidus points of the high purity samples were indistinguishable using precision resistance thermometry but one sample melted over a slightly smaller range of temperature than the other. Both these samples showed minor arrests on melting curves after induced freezing and detailed analyses of the melting contours after various types of freezing indicated some evidence of characteristic structure inside a range of 0.002 °C.