用慢应变速率拉伸和悬臂樑试验法研究了国产高强度预应力钢丝在饱和Ca(OH)_2+NaCl溶液中的应力腐蚀行为。结果表明,钢丝在含有氯离子的Ca(OH)_2溶液中会产生应力腐蚀开裂,其开裂敏感性随溶液中NaCl含量的升高和溶液pH值的降低而增大。Ca(OH)_2溶液中有Na_2SO_4存在也对钢丝的应力腐蚀带来不良影响。向Ca(OH)_2+NaCl溶液中添加NaNO_2可以抑制离氯子对钢丝应力腐蚀的有害作用。结合闭塞电池模拟试验中溶液pH值的变化以及极化电位和加载载荷谱对开裂敏感性的影响等试验结果,讨论了钢丝在Ca(OH)_2+NaCl溶液中应力腐蚀开裂的机理和应变率的作用。
The SCC behavior of a high strength prestressing steel wire in saturated Ca(OH)_2+NaCl solutions and the effects of various factors including concentration of NaCl, potentials, pH values of solution and other additives were studied by cantilever beam test or slow strain rate test.The results showed that the presence of NaCl or Na_2SO_4 in saturate Ca(OH)_2 solution promoted SCC of the steel wire. The susceptibility to SCC increased with the increase of NaCl concentration and with the decrease of pH values of solution. The addition of NaNO_2 in solution effectively prevented the deleterious action of chloride ions,Based on the effect of potentials on SCC behavior of steel wire and the pH value of solution in an occluded cell which simulated the conditions of crack tip, it is thought that the SCC of prestressing steel wire in saturated Ca(OH)_2+NaCl solutions at free potential is mainly controlled by anodic dissolution mechanism. The effects of the spectrum of loading on threshold stress intensity factor are discussed in the light of the action of strain rate at the crack tip.
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