4619
While the HIP treatment resulted in drop in hardness , HIP + HT led to ‘ recovery ’ of the hardness to values exceeding those exhibited by the aB-built material .
 HIP, hardness, HIP, led, hardness, material
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:
 HIP, hardness, HIP, led, hardness, material