1790
The maximum hardness is found to reach 462 ± 7 HV with a ∼ 460 μm hardened layer , and the surface stress state transforms from tensile to compressive after LSP .
 hardness, hardened, surface, stress, tensile
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:
 hardness, hardened, surface, stress, tensile