Corrosion Resistance and Microstructure of Welded Duplex Stainless Steel Surface Layers on Gray Cast Iron
Corrosion Resistance and Microstructure of Welded Duplex Stainless Steel Surface Layers on Gray Cast Iron
复制标题
DOI：
10.1007/s11666-020-01003-y
复制
发表时间：
2020-03-03
影响因子：
3.1
通讯作者：
Zokoll, E.
中科院分区：
文献类型：
--
作者：
Heider, B.;Oechsner, M.;Zokoll, E.
腐蚀和复杂的同时发生的损坏机制（例如冲蚀腐蚀和气蚀腐蚀）会导致泵部件退化，从而导致零件更换和维护成本高昂。为了提高具有优异铸造性能的经济高效部件的使用寿命，采用惰性保护气体金属电弧表面焊 (GMA-SW) 和等离子转移电弧表面焊 (PTA-SW) 在灰铸铁零件上进行双相不锈钢表面焊接。所用保护气体的热导率和预热温度影响表层的稀释度，从而对耐腐蚀性能和显微组织产生重大影响。较低的冷却速率增强扩散并导致碳化物沉淀。表面焊接过程中的高热输入和延长的冷却时间导致了高稀释度和碳化物网络。与具有较低热输入和较高冷却速率的表面层相比，这些表面层在人造海水中的耐腐蚀性大大降低。动电位极化试验中表面层的腐蚀是由Cr碳化物和贫Cr奥氏体之间相界的选择性腐蚀驱动的。在低稀释度的表面层中观察到钝化行为，其具有均匀的铬分布并且没有碳化物网络。总之，通过表面焊接双相不锈钢改善了灰铸铁的腐蚀行为。未经预热的 PTA-SW 生产的表面层的耐腐蚀性超过了 GMA-SW 生产的表面层，并且接近用作参考材料的市售双相不锈钢的耐腐蚀性。
The degradation of pump components by corrosion and complex, simultaneous damage mechanisms, e.g., erosion-corrosion and cavitation-corrosion leads to high costs through replacement and maintenance of parts. To increase the lifetime of cost-efficient components with superior casting properties, surface welding of duplex stainless steel on gray cast iron parts was performed using inert shielding gas metal arc surface welding (GMA-SW) and plasma transferred arc surface welding (PTA-SW). The thermal conductivity of the used shielding gas and the preheating temperature influenced the dilution of the surface layers, which had a major impact on the corrosion resistance and the microstructure. Lower cooling rates enhanced diffusion and lead to precipitation of carbides. High heat input and prolonged cooling times during surface welding resulted in high dilution and a carbide network. The corrosion resistance in artificial seawater of those surface layers was substantially reduced compared to surface layers with lower heat input and higher cooling rates. The corrosion of the surface layers in the potentiodynamic polarization test was driven by selective corrosion of the phase boundary between Cr-carbides and Cr-depleted austenite. Passive behavior was observed for surface layers with low dilution, which had homogeneous chromium distribution and no carbide networks. In conclusion, the corrosion behavior of gray cast iron was improved by surface welding with duplex stainless steel. The corrosion resistance of the surface layers produced with PTA-SW with no preheating exceeded that of the surface layers produced with GMA-SW and came close to those of a commercially available duplex stainless steel used as reference material.