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在低碳钢/(1NNa_2CO_3+1NNaHCO_3溶液)系统中,曾经观察到光滑试样的应力腐蚀裂纹在低频交变载荷作用下出现早期扩展阻滞现象,本工作采用70/30黄铜光滑试样在1NNaNO_2水溶液中的应力腐蚀开裂对这一现象进行了研究分析。实验结果说明:该阻滞效应在细晶粒黄铜中比在粗晶粒黄铜中更为显著;前者在晶界或孪晶界形成的裂绞数目比后者的要多得多;采用预裂绞试样能够消除这一阻滞效应。用光滑试样表面多重裂绞萌生可对以上结果作出解释一多重萌生的裂纹在早期扩展阶段有效地分散了裂绞尖端的应变集中。
In the low carbon steel / (1NNa_2CO_3 + 1NNaHCO_3 solution) system, it has been observed that the stress corrosion cracking of smooth specimens appears early expansion retardation under the effect of alternating alternating loads with low frequency. This work used a 70/30 brass smooth specimen Stress corrosion cracking in aqueous solution of 1NNaNO 2 has been studied. The experimental results show that the blocking effect is more pronounced in fine-grained brass than in coarse-grained brass; the former has much more splits than the latter in the grain boundaries or twin boundaries; Pre-splitting samples can eliminate this blocking effect. The above results are explained by the multiple crack initiation on a smooth sample surface. A multiple initiation crack effectively disperses the strain concentration at the tip of the crack at the early stage of expansion.