Fracture Statistics Dominated by Hot-Cutting Defect and Deviation from Weibull Distribution

This paper characterizes the rarely noticeable hot-cutting defect and statistically models the fracture governed by this new type defect. The morphology of the defect on fired ceramic is examined and quantitatively featured through comparing the fracture strength governed by intrinsic defect and hot-cutting defect. Weibull distribution is utilized to fit the observed strength data and chi-square goodness-of-fit test is conducted to analyze the deviation. Kernel density estimation is introduced to explore the underlying strength distribution dominated by hot-cutting defect. Based on the shape information from kernel density estimating,gamma and lognormal distribution are compared and the hot-cutting defect governing fracture statistics is finally confirmed by chisquare test. Results show that the newly-defined hot-cutting defect is more dangerous than the intrinsic defect and the priori Weibull distribution fails to describe the fracture statistic governed by the edge defect while the lognormal with a slightly right skewed shape fits it very well.

Thermal analysis control of in-mould and ladle inoculated grey cast irons

The effect of addition of 0.05wt.% to 0.25 wt.% Ca,Zr,Al-FeSi alloy on in-ladle and in-mould inoculation of grey cast irons was investigated.In the present paper,the conclusions drawn are based on thermal analysis.For the solidification pattern,some specific cooling curves characteristics,such as the degree of undercooling at the beginning of eutectic solidif ication and at the end of solidifi cation,as well as the recalescence level,are identif ied to be more influenced by the inoculation technique.The degree of eutectic undercooling of the electrically melted base iron having 0.025% S,0.003% Al and 3.5% Ce is excessively high(39-40℃),generating a relatively high need for inoculation.Under these conditions,the in-mould inoculation has a more signif icant effect compared to ladle inoculation,especially at lower inoculant usage(less than 0.20 wt.%).Generally,the eff iciency of 0.05wt.% -0.15wt.% of alloy for in-mould inoculation is comparable to,or better than,that of 0.15wt.% -0.25wt.% addition in ladle inoculation procedures.In order to secure stable and controlled processes,representative thermal analysis parameters could be used,especially in thin wall grey iron castings production.