热水器内胆焊缝周围鳞爆原因分析

用 SPCC冷轧低碳钢带生产的热水器内胆的焊缝及焊缝周边区域容易出现鳞爆缺陷,取用 SPCC冷轧低碳钢带制作生产的正常内胆与焊缝及焊缝周边出现鳞爆缺陷的不合格内胆进行分析对比,认为 SPCC冷轧低碳钢的抗鳞爆性能并不高,其固氢能力主要依赖于弥散分布于铁素体组织中的游离渗碳体实现,搪烧后,游离渗碳体出现铁素体晶界偏聚,本身抗鳞爆性能急剧下降。其焊接处易出现鳞爆缺陷,主要由于焊接过程中空气或材料本身附着水蒸气在电弧区发生分解,水分解产生的氢会增加焊缝的含氢量,而 SPCC材质本身较低的抗鳞爆性能导致焊缝区更易发生鳞爆。

Cause analysis of fish scaling around weld seam on water heater inner tank

Fish scaling defects were easy to occur around weld seam on water heater inner tank produced by SPCC cold-rolled low carbon steel strip,and the normal inner tank produced by SPCC cold-rolled low carbon steel strip was compared with the unqualified inner tank with fish scaling defects in and around the weld. It was consideredthat the fish scaling resistance of SPCC cold-rolled low carbon steel was not high,and its hydrogen fixation ability mainly depended on the free cementite which was dispersed in the ferrite structure. After enameling,free cementite segregated atthe grain boundary of ferrite,and its fish scaling resistance property decreased sharply. Fishs caling was easy to occurin the weld. It was mainly due to the decomposition of water vapor attached to air or material in the arc zone during the welding process.Hydrogen generated by water decomposition would increase the hydrogen content of the weld.The low fishscaling resistance property of SPCC material resulted in fish scaling happened easier at weld seam zone.