Research on Low Temperature CTOD Fracture Toughness and da/dN Properties of S355N and S355N-Z25 Structural Steel Plate
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摘要: 分别采用三点弯曲SE(B)与紧凑拉伸C(T)试样,通过-20℃的低温裂纹尖端张开位移CTOD断裂韧性试验及疲劳裂纹扩展速率da/dN试验,研究了S355N及S355N-Z25结构钢的裂纹启裂与扩展的抗力。研究结果表明:S355N钢抵抗裂纹启裂及前期扩展的能力比S355N-Z25钢强,但前者抵抗裂纹后期扩展的能力比后者弱;当应力强度因子范围ΔK小于34.3 MPa.$\sqrt {\rm{m}} $时,S355N钢的疲劳抗力比S355N-Z25钢弱,当ΔK等于34.3 MPa.$\sqrt {\rm{m}} $时,两者具有相同的疲劳抗力,当ΔK大于34.3 MPa.$\sqrt {\rm{m}} $时,前者的疲劳抗力比后者强。研究结果对两种钢板在工程上应用及结构的安全评定提供了参考。
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关键词:
- S355N及S355N-Z25钢板 /
- 低温CTOD断裂韧性 /
- 疲劳裂纹扩展速率da/dN /
- 裂纹启裂 /
- 裂纹扩展 /
- 抗力
Abstract: Adopting three-point bend SE(B) and compact tensile C(T) specimen,through crack-tip opening displacement CTOD fracture toughness test at-20℃ and fatigue crack propagation rate da/dN test,resistance to crack initiation and propagation of S355N and S355N-Z25 structural steel plates were studied.The results manifested that S355N steel is stronger in resistance to crack initiation and prophase growth than S355N-Z25 steel,but is weaker to crack anaphase propagating.When stress strength factor ΔK is less than 34.3MPa·$\sqrt {\rm{m}} $,S355N steel has less fatigue resistance than S355N-Z25 steel.When ΔK equals 34.3MPa·$\sqrt {\rm{m}} $,both have the same fatigue resistance.When ΔK is more than 34.3MPa·$\sqrt {\rm{m}} $,the former has stronger fatigue resistance than the latter.These information may provide reference for the steels as used in safety-assessing of engineering structure. -
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