SUMITOMO 347AP is similar to what could be called Type 347LN and was developed to prevent polythionic acid cracking in chromium depleted grain boundary areas. The columbium (niobium) content is maintained at a ratio of greater than 15 times the carbon in addition to maintaining very low carbon levels. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on forming, heat treating, and joining. Filing Code: SS-548. Producer or source: Sumitomo Metal USA Corporation.