Various Properties of High-Density Sintered Stainless Steel Obtained by Powder Compacting

Stainless steel is used in a wide range of applications due to excellent mechanical properties and corrosion resistance. However, there is a difficulty in forming unmachinable small diameter and deep holes since stainless steel is a difficult-to-cut material. Additionally, the application of sintered stainless steel is limited to items that do not require airtightness due to the presence of pores inside the material. Although a method of increasing the density using liquid phase sintering was considered to reduce internal pores of sintered stainless steel, it significantly affects dimensional accuracy and post-processing after sintering because of the generation of large amount of shrinkage. In order to solve the above issues, we developed a high-density green machining method that combines a technique to increase density during powder compaction and a green machining process. We have succeeded in producing a stainless steel sintered material with a density of 95 vol% that does not leak even when evaluated for tightness under high-pressure hydrogen conditions of 70 MPa.