150kgf/mm^2級中炭素鋼の低温焼きもどし後の靱性におよぼす粒界りん偏析およびボロン添加の効果

概要

論文の詳細を見る
Effects of phosphorus content and boron addition on impact toughness of medium carbon steels with an ultra-high strength level over 150kgf/mm^2 have been investigated. The toughness is deteriorated by two independent fracture modes, that is, intergranular fracture and Tempered Martensite Embrittlement (TME). Intergranular fracture is greatly enhanced with the increase in phosphorus content of steel, whereas the boron addition is effective in reducing it and increases toughness over the whole range of tempering temperatures below 400℃. However, phosphorus content and boron addition have no significant effect on TME. Auger Electron Spectroscopic (AES) observation reveals that boron addition reduces the intergranular fracture by reducing the phosphorus segregation at the grain boundaries. The estimation by diffusion calculation and McLean's grain boundary equilibrium segregation model shows that boron segregates to grain boundaries much faster than phosphorus does at austenitizing temperatures and reduces the boundary energy for phosphorus segregation.
社団法人日本鉄鋼協会の論文
1991-12-01