Fastening part e.g. bolt, for fastening e.g. rock, has intermediate zone formed of ferritic steel arranged between core and edge zones, where hardness of intermediate zone is smaller than carbon-containing steel of core zone

摘要

The part has a core zone (14) made of carbon-containing steel with a hardness of 30-662 Rockwell C Hardness (HRC). An edge zone (17) of low carbon austenitic steel is blended with an alloy metal, where the edge zone lies outside relative to core zone. An intermediate zone (15b) formed of ferritic steel is arranged between the core zone and the edge zone, where hardness of the intermediate zone is smaller than the carbon-containing steel of the core zone. A thickness of the intermediate zone perpendicular to a surface of the core zone is ranges from 0.001 millimeters and 1.0 millimeters.