The 4J6 has an expansion coefficient similar to the soft glass in the temperature range of 20 to 400℃. For matching and sealing with the corresponding soft glass. This kind of alloy contains chromium. After oxidation treatment, the alloy surface produces a very dense oxide film, which is strongly bound with the matrix, and has a good infiltration with soft glass. Therefore, a high-strength sealing surface can be obtained. It is an important sealing structure material in the electric vacuum industry.