45MnSiV预应力钢筋的应力腐蚀

STRESS CORROSION CRACKING OF 45MnSiV PRE-STRESSING STEEL

用慢应变速率、动电位扫描和断口分析等试验方法,研究了45MnSiV 预应力高强度钢筋的应力腐蚀行为。结果表明,在未受侵蚀的混凝土中.45MnSiV 预应力钢筋不会发生应力腐蚀开裂;若 HCl,NaCl 或 SO_2等侵入混凝土,使其 pH 值下降,则会出现阳极溶解型的应力腐蚀。45MnSiV 预应力钢筋的最佳阴极保护电位为-800mV(SCE)左右。如果外加电位偏低,则不论混凝土受侵蚀与否,均将引起45MnSiV 预应力钢筋的氢致开裂。

The stress corrosion cracking (SCC) behavior of 45MnSiV pre-stressing high strength steel has been studied with slow strain rate tests (SSRT),electro-chemical and fractographic techniques.The SSRT were performed in saturated Ca(OH)_2 solutons,at various applied potentials from-1200 to-400mV(SCE).Some HCl was added to the solution in order to adjust the pH within the range 12.5～5.In addition,the cases that concrete has been polluted by Cl^- ion or SO_2 have also been investigated.The experiments are so designed as to truthfully imitating the service conditions of steel in concrete.The re- suits have shown that no SCC of 45MnSiV pre-stressing steel was observed in the concrete which has not been polluted.If some HCI.NaCl or SO_2 penetrate the concrete and decrease the pH value,SCC which appears to be related to anedic dissolution occurs.The best ca- thodic protection potential is in the vicinity of-800mV (SCE).Howevr,if the applied po- tential is lower than-900mV(SCE),cracking will occur which results from the ingress of hydrogen into steel,irrespective of any other conditions.