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The results show that pre-heating effect from previously built layers can be effectively used to reduce residual stresses ; cooling rate firstly decreased rapidly and then kept stable in the 15th–25th layers .
 material: be; machanical property: residual stresses; process parameter: cooling rate
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:
 material: be; machanical property: residual stresses; process parameter: cooling rate