强化核阀密封面的NOREM02激光熔覆层性能研究

Performance of Fe-based hardfacing alloys in plant valves with laser cladding

选用无钴NOREM02铁基粉末在不锈钢基体上进行激光熔覆。对在不同工艺参数下熔覆层形貌、微观组织及显微硬度进行观察和测试,并进行了物相分析。采用静态浸泡法对NOREM02铁基激光熔覆层的耐腐性进行研究,并与Stellite6钴基熔覆层和不锈钢基体对比。结果表明:NOREM02铁基粉末在优化的激光熔覆工艺参数下,可获得表面连续光滑,宽度和厚度均匀的熔覆层。该熔覆层组织致密,晶粒细小,结合区牢固,显微硬度600 HV0.5以上,具有强韧两相组成(奥氏体和M7C3)的微观特征。在10%H2SO4和10%NaC l溶液中铁基熔覆层抗腐蚀性能接近钴基熔覆层。

NOREM02 Fe-based alloy was selected to produce hard coating by laser cladding on the stainless steel substrate,for its good evaluation in some foreign hardfacing applications to replace cobalt-based alloys.The macro morphology,microstructure and micro-hardness of the single passes,manufactured with different processing parameters,were observed and measured,and moreover the phases of coatings were analyzed.The corrosion resistance of Fe-based coatings was investigated with the method of static immersion.The experimental results showed that：the continuous and smooth coatings manufactured in the optimized processing parameters can be obtained in the features of homogeneous width and heights.The coatings had dense microstructure,fine grain and firm metallurgical bonding,with 600 HV0.5 and above micro-hardness.The phases were mainly consisted by austenite and M7C3,in which austenite was served as ductile matrix and M7C3 as reinforcement phases.The Fe-based coatings showed well corrosion resistance in the solution of 10% H2SO4 and 10%NaCl,matching to Co-based coatings.