2172
Initially , during the pre-sintering at 1150 °C , evidences of neck formation between the 420 stainless steel particles were observed .
 pre-sintering, 420 stainless steel
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:
 pre-sintering, 420 stainless steel