1991
Although major strides have been made towards understanding the effect of hot isostatic pressure ( HIP ) on the mechanical properties of Ti-6Al-4V produced by AM , its effect on corrosion performance remains relatively unexplored .
 concept or principle: pressure; manufacturing process: HIP; concept or principle: mechanical properties; material: Ti-6Al-4V; manufacturing process: AM; concept or principle: corrosion
Given options, please tell me the categories of all the listed entity words.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} 
 Entities: pressure, HIP, mechanical properties, Ti-6Al-4V, AM, corrosion 
Answer:
 concept or principle: pressure; manufacturing process: HIP; concept or principle: mechanical properties; material: Ti-6Al-4V; manufacturing process: AM; concept or principle: corrosion