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When do you add grain refiner compared to other treatments (degassing/fluxing)? A near equal split was seen in responses with regard to


grain refiner addition before, during, or after degassing and fluxing. 31% of respondents said they add before, 27% during, and 24% after, with the remainder either adding continuously throughout production or they do not degas or flux (14%). While this survey does not necessarily define best practices, it would be interesting to know what sort of yield or effect is seen among these metalcasting facilities based on these differ- ences in process.


Why do you add grain refiner? Te primary reason stated for adding grain refiner is to reduce


grain size, leading to an increase in mechanical properties (70%). Improved flowability and better heat-treatability each were cited as primary reasons for 10% of respondents, with only 2% citing a customer requirement for refiner additions. Interestingly, 5% of respondents said they did not know why they added the refiner, but it resulted in better castings.


Approximately how long before pouring is the grain refiner added?


Most metalcasters are in agreement when it comes to the timing of additions relative to pouring, saying refiners should


be added between 0 and 15 minutes prior to casting (70%) and no earlier than 30 minutes before casting (92%). When asked to provide one tip about grain refining,


some respondents answered as follows: “Te most important thing about grain refining is the amount of lapsed time between the addition made and time of pour; about 45 minutes beginning to end.” “Do not over grain refine. Keep Ti levels below 0.12% in


A356 alloy but above 0.10%.” “All manufacturers are not equal; you get what you pay for.” Additionally, respondents indicated it is best to make sure


the part being cast needs the addition; simple, non-structural components may not require refiner additions. Small addi- tions at the proper time and in the proper location (ladle vs melting furnace) would help deter any particle buildup and avoid “over refining” the microstructure with larger additions at one time. Finally, know your source of refiner regardless of the method in which it’s introduced.


AFS Eutectic Modification Survey A similar distribution of alloys being cast was seen from


respondents to this survey as in the grain refiner surve. Which eutectic modifier do you use most often? Of the response options to this question (Sr, Na, Sb, CuP,


November 2016 MODERN CASTING | 45


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