9391
Using tungsten inert gas welding , a simple technique to additively construct single-channel multilayer Ti alloy ( Ti-6Al-4V ) was developed .
 tungsten inert gas welding, simple, Ti alloy, Ti-6Al-4V
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:
 tungsten inert gas welding, simple, Ti alloy, Ti-6Al-4V