Ni-Cr-B-Si alloy is used for hardfacing of 316 L N Stainless Steel components in Sodium-cooled Fast Reactors (SFRs) to enhance wear resistance and also to prevent self-welding. Since the shear force is acting between the substrate and the deposit due to dissimilar thermal expansion during high temperature operating conditions, it is necessary to focus on the hardfacing process which provides good bonding shear strength between them. Though low substrate dilution is advisable to attain high microhardness of the deposit, the deposit should not get de-bonded due to shear. To seek solution to this problem, three major hardfacing processes, viz., Plasma Transferred Arc, Gas Tungsten Arc and Laser processes were considered. Hardfaed shear specimens were prepared using each process and tested as per the ASTM A264. Faster cooling rate leads to finer grains and higher microhardness. The influence of dilution on the microhardness was studied. Scanning Electron Mircographs and Energy Dispersive Spectroscopic studies at the fractured surfaces were done to ascertain the reason for strength. Finally, the laser hardfacing process which provides a combination of good shear strength, high microhardness as well as low dilution is recommended for hardfacing of the components of the SFRs for their reliable operations.

Ni-Cr-B-Si合金用于钠冷快堆（SFR）中的316 L N不锈钢组件的表面硬化，以增强耐磨性并防止自焊接。由于在高温操作条件下，由于不同的热膨胀，剪切力作用在基材和沉积物之间，因此有必要集中精力进行表面硬化工艺，以在它们之间提供良好的粘结剪切强度。尽管建议使用低的基材稀释度以获得较高的镀层显微硬度，但镀层不应因剪切而脱粘。为了寻求解决该问题的方法，考虑了三种主要的堆焊工艺，即等离子转移弧，钨极电弧和激光工艺。使用每种方法制备硬质剪切标本，并按照ASTM A264进行测试。更快的冷却速度导致更细的晶粒和更高的显微硬度。研究了稀释对显微硬度的影响。在断裂表面上进行了扫描电子显微镜和能量色散光谱研究，以确定强度的原因。最后，建议对SFR组件进行可靠的操作，使其具有良好的剪切强度，高的显微硬度以及低的稀释度，同时进行激光表面硬化处理。