280kg/mm2級マルエージ鋼の加工熱処理条件と強靱性
1978 年 64 巻 7 号 p. 1063-1071
詳細
1978 年 64 巻 7 号 p. 1063-1071
In order to produce the ultrahigh strength maraging steel plate with excellent ductility and toughness, and free from the anisotropy in the maechanical properties, the effects of processing variables in thermomechanical treatment on the mechanical properties of 13Ni-15Co-10Mo steel have been investigated. The relation between prior austenite gtain size and the mechanical properties has also been investigated. The austenite grain size attainable is greatly affected by the reduction in rolling. The grain refinement increases the tensile strength and ductility, but does not improve fracture thoughness. The anisotropies of strength and ductility are found to be related to the occurrence of the unrecrystallized austenite grain, whereas the anisotropy of fracture toughness is not observed for all the conditions. Thus, the recrystallized and fine grained structure is found favorable to produce the excellent combination of the strength, ductility, and isotropy. Such a microstructure is produced by choosing the optimum conditions in the thermomechanical treatment, which involve the rolling temperature and reduction.
