Investigation on Heat Treatment of Cold-rolled Stell 15 Under High Pressure
The martensitic steel 15 was heat treated under high pressure in the CS-IB type hexahedron anvils press.The Vickers hardness of the sample was measured.The morphology and the crystal structure were analyzed by TEM and X-ray diffraction.The results show that recovery and recrystallization occurr at 350℃ and 450~650℃ at 6GPa,respectively.Martensitic transformation takes place when heated to 750℃ and 850℃ at 6GPa.The product has two microstructures,one is acicular martensite(bcc) and the other is latticework martensite(hcp).The sample hardness changes due to the changes of the microstructure.