2574
In the present study , 18Ni maraging steel samples were built by selective laser melting , homogenized at 820 °C and then subjected to different isothermal tempering cycles aiming for martensite-to-austenite reversion .
 maraging steel, selective laser melting, homogenized, isothermal
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:
 maraging steel, selective laser melting, homogenized, isothermal