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However , post-process technologies have their own limitations , for instance , peening and ultrasonic impact treatment only improve material property and reduce defects near the part surface , while extended heat treatment of certain materials promotes grain growth rather than grain refinement .
 concept or principle: post-process; manufacturing process: peening; process characterization: ultrasonic impact treatment; concept or principle: material property; concept or principle: defects; concept or principle: surface; manufacturing process: heat treatment; concept or principle: materials; concept or principle: grain growth; process characterization: grain refinement
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: 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:
 concept or principle: post-process; manufacturing process: peening; process characterization: ultrasonic impact treatment; concept or principle: material property; concept or principle: defects; concept or principle: surface; manufacturing process: heat treatment; concept or principle: materials; concept or principle: grain growth; process characterization: grain refinement