The application of components often depends to a large extent on the properties of the surface layer.A novel process chain for the production of components with a hardened surface layer from metastable austenitic stee...The application of components often depends to a large extent on the properties of the surface layer.A novel process chain for the production of components with a hardened surface layer from metastable austenitic steel was presented.The investigated metastable austenitic AISI 347 steel was cold-drawn in solution annealed condition at cryogenic temperatures for pre-hardening,followed by post-hardening via cryogenic turning.The increase in hardness in both processes was due to strain hardening and deformation-induced phase transformation from y-austenite to^-martensite.Cryogenic turning experiments were carried out with solution annealed AISI 347 steel as well as with solution annealed and subsequently cold-drawn AISI 347 steel.The thermomechanical load of the workpiece surface layer during the turning process as well as the resulting surface morphology was characterized.The forces and temperatures were higher in turning the cold-drawn AISI 347 steel than turning the solution annealed AISI 347 steel.After cryogenic turning of the solution annealed material,deformation-induced phase transformation and a significant increase in hardness were detected in the near-surface layer.In contrast,no additional phase transformation was observed after cryogenic turning of the cold-drawn AISI 347 steel.The maximum hardness in the surface layer was similar,whereas the hardness in the core of the cold-drawn AISI 347 steel was higher compared to that in the solution annealed AISI 347 steel.展开更多
文摘The application of components often depends to a large extent on the properties of the surface layer.A novel process chain for the production of components with a hardened surface layer from metastable austenitic steel was presented.The investigated metastable austenitic AISI 347 steel was cold-drawn in solution annealed condition at cryogenic temperatures for pre-hardening,followed by post-hardening via cryogenic turning.The increase in hardness in both processes was due to strain hardening and deformation-induced phase transformation from y-austenite to^-martensite.Cryogenic turning experiments were carried out with solution annealed AISI 347 steel as well as with solution annealed and subsequently cold-drawn AISI 347 steel.The thermomechanical load of the workpiece surface layer during the turning process as well as the resulting surface morphology was characterized.The forces and temperatures were higher in turning the cold-drawn AISI 347 steel than turning the solution annealed AISI 347 steel.After cryogenic turning of the solution annealed material,deformation-induced phase transformation and a significant increase in hardness were detected in the near-surface layer.In contrast,no additional phase transformation was observed after cryogenic turning of the cold-drawn AISI 347 steel.The maximum hardness in the surface layer was similar,whereas the hardness in the core of the cold-drawn AISI 347 steel was higher compared to that in the solution annealed AISI 347 steel.
