Premium Quality Super Duplex Stainless Steel Castings Without Secondary Refining

摘要

The ASTM A890/ A995 (25Cr 7Ni 3.5Mo) super duplex stainless steels are a popular family of high alloy cast steels used extensively in the power generation and energy sectors. The manufacturing steps for these alloys have up to now required the use of costly secondary refining processes such as Argon Oxygen Decarburization (AOD). This paper will describe and validate a set of process parameters that obviate the need for secondary refining. Initial results indicate that the principle embrittling features, carbides and sigma phases, are not found, confirming the proposal that these phases form on bifilms entrained by surface turbulence during pouring. Other significant benefits from the absence of bifilms appear to include the elimination of cracking and leakage defects.