682
For HT1 , due to the B2 → O transformation , the microstructure of heat affected zone was B2 + α2 + O , B2 + residual α2 + O , and B2 + O as the distance from the base metal increased .
 material: O; concept or principle: microstructure; concept or principle: heat affected zone; material: O; concept or principle: residual; material: O; material: O; material: as; material: base metal
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: O; concept or principle: microstructure; concept or principle: heat affected zone; material: O; concept or principle: residual; material: O; material: O; material: as; material: base metal