HU Zheng-fei
,
WANG Chun-xu
钢铁研究学报(英文版)
The effects of spinning deformation and subsequent heat treatments on the mechanical properties and microstructure of 18Ni Co-free Maraging steel (T250) tube were evaluated comparatively with the perform. An obvious radial shrinkage is detected in spun tubes after heat treatment and the magnitude of the shrinkage induced by solution treatment is almost the same as that by aging. Plastic deformation during spinning elongated the grains severely in the direction of metal flow. The solution treatment resulted in a drastically refined grain and recrystallised microstructure, removing the effect of plastic deformation, relieving the tangential residual stress and strain and improving hardness. Subsequent aging obtained a tempered microstructure, enhancing hardness values strikingly for precipitation strengthening. XRD (X-ray diffraction) analysis indicated that the reversed austenite formed in a plate-like along the grain boundaries and the volume fraction of austenite in spun tube was more than double that in the preform. These results imply that the residual stress and stain induced by spinning process and reversed austenite forming during aging might have the similar contribution to the radical shrinkage.
关键词:
maraging steel
,
spinning process
,
plastic deformation
,
heat-treatment
,
microstructure
,
reversed austenite
LIU Yu-rong
,
YE Dong
,
YONG Qi-long
,
SU Jie
,
ZHAO Kun-yu
,
JIANG Wen
钢铁研究学报(英文版)
The microstructures and mechanical properties of Cr13 super martensitic stainless steel after different heat treatments were studied. The results show that the structures of the steel after quenching are of lath martensite mixed with a small amount of retained austenite. With the raising quenching temperature, the original austenite grain size increases and the lath martensite gradually becomes thicker. The structures of the tempered steel are mixtures of tempered martensite and reversed austenite dispersed in the martensite matrix. The amount of reversed austenite is from 754% to 2249%. After different heat treatments, the tensile strength, the elongation and the HRC hardness of the steel are in the range of 813-1070 MPa, 101%-212% and 2133-3237, respectively. The steel displays the best comprehensive mechanical properties after the sample is quenched at 1050 ℃ followed by tempering at 650 ℃.
关键词:
super martensitic stainless steel
,
quenching
,
tempering
,
structure
,
property
,
reversed austenite
