【摘要】 在A356合金熔体中加Sr是改善其力学性能的一种变质处理工艺,但也带来了一些负面影响。采用减压凝固法研究了加Sr对A356熔体氢含量的影响。结果表明,加Sr后的合金氢含量和减压凝固试样断面气孔的数量明显高于未加Sr的合金。加入Sr后,在铝熔体表面氧化膜中出现有锶的氧化物。由于锶的氧化物的致密度α<1,使A356合金熔体的表面氧化膜变得疏松,易开裂,加大了在熔炼过程中新鲜铝液暴露在大气下与H2O、O2反应的几率,降低了原氧化膜的防二次污染作用。显然,这是导致熔体氢含量的增加、吸氢倾向加重的重要原因。更多还原

【Abstract】 Adding Sr element in the A356 melt is one of the processes used to improve mechanical properties of the A356 alloy,but Sr brings some negative effects.The influence of the Sr on hydrogen content of the A356 melts by adopting the reduced pressure test was studied.The results indicatthat the hydrogen content and the porosity quantity in the cross-section of strontium-treated samples are obviously higher than those of the alloy without strontium addition.It is found that The Sr oxide is generated on the surface oxide film with Sr addition.Owing to the compactness α<1,Sr oxide makes the surface oxide film looser and easier to crack,thus enhances the possibility of new melted aluminum alloy to react with water vapor and oxygen and impair the role of original oxide film on preventing the second pollution.It is apparent that it is the main reason to result in the increase of hydrogen content.更多还原