【摘要】 研究了35SiMnMoV贝氏体钢热处理后马氏体+贝氏体复相组织的微观参量对平面应变断裂韧度、缺口韧度及塑性的影响。结果表明,裂纹韧度受控于裂尖前沿有效变形区尺寸2δc(δc临界裂纹张开位移)范围内的显微组织参量,在一定的根部半径范围(ρ=016mm)内,控制缺口韧度的微参量与裂纹韧度相同,塑性则受控于原奥氏体晶粒尺寸dγ。计算的2δc与测定的深缺口临界根部半径ρ0有对应关系。裂纹韧度与缺口韧度的关系取决于2δc与贝氏体之间的平均自由距离dB。当2δc>(1～2)dB时,裂纹韧度与缺口韧度的变化一致;2δc<(1～2)dγ时,裂纹韧度、缺口韧度与塑性的变化趋势不同。更多还原

【Abstract】 The influence of microstructural parameters of martensite (M) and bainite (B) mixed structure on plane strain fracture toughness,notch toughness and tensile ductility have been investigated for the heat treated 35SiMnMoV bainite steel.The results showed that fracture toughness was controlled by the micro\|structural parameters in the extent of effective deformed region 2δ c( δ c-the crack tip opening displacements at critical) ahead of the crack tip.In a certain extent of root radius ( ρ =0.16mm),the microstructural parameters controlling notch toughness were as same as the one of crack toughness.Whereas tensile ductility was dominated by austenite grain size d \-γ.The computed 2 δ c values corresponded to the experimental deep notch root radius ρ 0 .The relationship between fracture toughness and notch toughness depended on the relative size of effective deformed zone 2 δ c and mean free distance d B between bainites.When 2 δ c>(1～2) d \-B,the fracture toughness coincided with notch toughness,when 2 δ c<(1～2) d \-γ,fracture toughness,notch toughness did not coincid with tensile ductility.更多还原