MEMBER FOR BOILER PROVIDED WITH CO ALLOY BUILD-UP LAYER

摘要

PURPOSE:To improve the resistance to erosion and corrosion by forming a Co alloy build-up layer into which specific % or above of Cr is incorporated and which has prescribed Vickers hardness. CONSTITUTION:The Co alloy build-up layer contg. >=20% Cr and having 400-550kgf/mm<2> Vickers hardness at an ordinary temp. is formed to a boiler pipe material consisting of a stainless steel or Cr-Mo steel, etc. The hardness after the building up is controlled by adjusting the content of C in this stage. The erosion resistance is remarkably improved if the hardness of the build-up layer is >=400kgf/mm<2> but the resistance to deformation decreases when the hardness exceeds 550kgf/mm<2>. Since the content of Cr is >=20%, the resistance to corrosion at a high temp. and sulfide corrosion is improved. The resistance to erosion and corrosion of the member for a boiler is thus improved by the above-mentioned method.