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The paper presents results of the possibility of adapting the Althoff-Radtke test for High Chromium Cast Iron. The Althoff-Radtke test is a clump attempt used for steel. The Althoff-Radtke test has four different lengths of clamp which qualifies it as a test to quantitatively take into account different kinds of shrinkage ΔL. The length of the slot of the cracked corner and the length of each staple (50 - 350 mm) are the parameters tendency to cast cracks. Castings of white cast iron have a high tendency to hot cracking due to the large range of solidification temperatures, unfavorable kinetics parameters of shrinkage, and especially a lack of expansion before shrinkage. Shrinkage of high chromium white cast iron is similar to the shrinkage of cast steel, and is approximately 2%. Therefore it is important to test susceptibility to hot cracks. Research was carried out under industrial conditions. Four melts were performed, one of the initial chemical composition and the other three modified by different amounts of Fe-Ti, respectively, 0.25%, 0.5% and 0.75% Fe-Ti. The propensity for hot cracking was based on the observation of the dark surface in the corner of the sample. The study shows that the Althoff-Radtke test can be adapted to determine the tendency for hot cracking of high chromium cast iron. It should however be noted that the test results cannot be compared with those for other alloys.

In order to modify in-situ synthesized Mg2Si particles in Mg2Si/Mg-4Si composite, the modification effect of calcium-magnesia phosphate fertilizer on primary Mg2Si phase in Mg2Si/Mg-4Si composite was investigated by means of X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. The results indicate that the morphology of the primary Mg2Si phase apparently changes from coarse dendrites to fine dispersive polygonal particles, and the mean size is decreased from 277 μm to 17 μm. With the addition of 4.0wt.% calcium-magnesia phosphate fertilizer as a modifier, the ultimate tensile strength and elongation of the Mg2Si/Mg-4Si composite are increased from 78.7 MPa and 2.1% to 105.2 MPa and 2.6%, as compared to those of the base composite, which is probably attributed to the formation of the phosphorous compound and the cluster of Ca compounds that acted as the heterogeneous nucleation substrates of the primary Mg2Si particles, resulting in a refined distribution of these precipitates.

In order to modify in-situ synthesized Mg2Si particles in Mg2Si/Mg-4Si composite, the modification effect of calcium-magnesia phosphate fertilizer on primary Mg2Si phase in Mg2Si/Mg-4Si composite was investigated by means of X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis. The results indicate that the morphology of the primary Mg2Si phase apparently changes from coarse dendrites to fine dispersive polygonal particles, and the mean size is decreased from 277 µm to 17 µm. With the addition of 4.0wt.% calcium-magnesia phosphate fertilizer as a modifier, the ultimate tensile strength and elongation of the Mg2Si/Mg-4Si composite are increased from 78.7 MPa and 2.1% to 105.2 MPa and 2.6%, as compared to those of the base composite, which is probably attributed to the formation of the phosphorous compound and the cluster of Ca compounds that acted as the heterogeneous nucleation substrates of the primary Mg2Si particles, resulting in a refined distribution of these precipitates. [ABSTRACT FROM AUTHOR]