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In this research , inter-pass rolling was applied with a load of 50 kN to a tantalum linear structure to assess rolling ’ s effectiveness in changing the grain structure from columnar to equiaxed , as well as in refining the grain size .
 research, rolling, tantalum, structure, rolling, s, effectiveness, grain structure, as, as, grain size
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 research, rolling, tantalum, structure, rolling, s, effectiveness, grain structure, as, as, grain size