纯锆R60702板材焊接接头的腐蚀性能研究

Corrosion Property of Pure Zirconium R60702 Welded Joint

采用挂片失重法,研究了工业纯锆R60702板材钨极氩弧焊焊接接头分别在沸腾条件下的10%,30%,70%(质量分数)浓度的硫酸和醋酸+2%KI+200 mg·kg-1Na Cl介质中的腐蚀性能,并分析了接头腐蚀后的表面形貌及腐蚀机制。实验结果表明,在相同浓度硫酸介质中,焊接接头的腐蚀速率均比母材腐蚀速率大;当硫酸腐蚀液浓度低于30%(包含30%)时,母材和焊接接头均具有优异的腐蚀性能;当硫酸腐蚀液浓度高于30%时,母材和焊接接头腐蚀速率显著增大,硫酸浓度对母材和焊接接头的腐蚀速率影响均较大;在相同浓度醋酸+2%KI+200 mg·kg-1Na Cl混合介质中,接头的腐蚀速率均比母材腐蚀速率小;当醋酸浓度小于70%时,浓度对母材和接头的腐蚀性能影响较小,这是因为焊缝区域的粗大组织降低了Cl-和I-吸附晶界引起的氧化膜局部破坏效应;工业纯锆R60702母材和焊接接头在硫酸介质中腐蚀方式均为全面腐蚀,在醋酸+2%KI+200 mg·kg-1Na Cl混合介质中的腐蚀方式为点蚀。

The corrosion resistance of zirconium R60702 welded joint was studied in 10%, 30%, 70% （ mass fraction） sulfuric acid and acetic acid ＋2% KI ＋ 200 mg·kg-1 NaCl medium, respectively, using weight-loss method. Corrosion morphology and corrosion mechanism of the welded joint were analyzed. The results showed that in sulfuric acid medium of the same concentration, the corrosion rate of welded joints was higher than that of the base metal ; when the concentration of sulfuric acid corrosion liquid was less than 30% （ including 30% ）, both of the base metal and welded joint had excellent corrosion resistance ; when the concentration of sulfuric acid corrosion liquid was higher than 30% , the corrosion rate of base metal and welded joint increased significantly. The concentration of sulfuric acid had great effect on the corrosion property of base metal and welded joint ; in the acetic acid solution of the same concentration with 2% KI ＋ 200 mg·kg - 1 NaCl, the corrosion rate of welded joints was smaller than that of base material ; when the concentration of acetic acid was less than 70%, the concentration of acetic acid had few effects on the corrosion property of base metal and welded joint, due to that the coarse structure of weld area decreased local damage effect caused by Cl- and I- adsorption on the film grain boundary; the corrosion mechanisms of pure zirconium R60702 base metal and welded joint were overall corrosion in sulfuric acid and pitting in acetic acid ＋ 2% KI ＋ 200 mg·kg-1 NaCl medium.