autofrettage
/ˈɔːtə(ʊ)ˌfrɛtɪdʒ/ /ˌɔːtə(ʊ)frɛˈtɑːʒ/noun
The process of strengthening a tube, especially a gun barrel, by subjecting it to internal pressure high enough to enlarge the bore and push the inner metal (but not the outer metal) beyond its elastic limit.
Origin
Early 20th century. From auto- + frettage, after French autofrettage.