退火对A32钢焊接接头耐蚀性能的影响

Effects of anneal on the corrosion resistance properties of A32 welded joints

A32钢焊接接头广泛应用于船舶工业,其耐蚀性能的优劣对于焊接接头的力学性能和使用寿命至关重要.采用扫描电镜,超景深数码显微镜和电化学分析仪等表征手段,研究了船用A32钢焊接接头在进行去应力退火前后各部位在模拟海水溶液中的腐蚀行为,并对相关影响因素进行了讨论.结果表明:800℃去应力退火后,A32钢焊接接头部位耐蚀性能显著提高,这主要是由于在焊缝区和熔合区形成了趋向一致的树枝晶,母材组织铁素体增多,珠光体减少;另外,退火后的锈层成分为Fe_2O_3和α-FeOOH,较退火前的焊接接头锈层致密、覆盖完整,防腐蚀性能更好.

A32 steel is widely used in shipbuilding and the corrosion resistance properties of welded joints is key to the mechanical property and service life of welded joints. The corrosion behavior in simulated seawater of the annealed A32 welded joint was investigated using scanning electron microscope,super depth digital microscope and the electrochemical system,and the relevant factors were discussed. The results showed that the corrosion resistance properties of 800 ℃ annealed A32 welded joint had a great improvement because of the formation of dendritic grains growth,the increase of ferritein and the decrease of pearlite in the weld metal and fusion zone of annealed A32 steel. In addition,the rust layer annealed with 800 ℃ contained Fe3O2 and α-FeOOH,which turned to be denser,more corrosion-resistant than the rust layer without annealing and of complete coverage.