Influence of Composition and Processing on Properties of Stainless Steels

Abstract:

Stainless steels, by virtue of their diversity in chemistry, microstructure and properties, find widespread applications ranging from domestic appliances to high technology sectors such as space, aeronautics, power, chemical and ordnance. Midhani has been at the forefront of material development over the past few decades and has produced several stainless steels, tailor made for specific critical applications. Subtle variations in chemistry or processing methodology have been exercised to achieve the desired microstructure and properties. In this context, influence of minor addition of austenitic stabilizing element on structure and properties on conventional ferritic stainless steel SS430 was studied. The chemistry modification changed the structure to dual phase, austenite ferrite structure, that responded to heat treatment by transformation of austenite to martensite. This dual phase structure after tempering enhanced the strength and toughness by 25% and 60% respectively. In the case of 13-8 Mo PH stainless steel, a modified two stage solution treatment and ageing resulted in enhancement of toughness by over 100% as compared to conventional single stage solution treatment and the improvement was attributable to refinement in martensitic sub-structure due to thermal cycling. With respect to SS 440C, a high carbon stainless steel, the performance is closely related distribution of primary carbide. Bearing directly manufactured from forged stock produced from ingot do not perform satisfactorily in view of massive primary carbides present in the form of stringers / bands. This problem was addressed by subjecting the forged stock to further working in the transverse orientation by ring rolling which brought about finer primary carbides. The present paper highlights some of the challenges and the modifications brought about to meet the specific needs.

• Periodical: Advanced Materials Research (Volume 794)
• Pages: 117-123
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.794.117
• Online since: September 2013
• Authors: S. Narahari Prasad, K. Rajasekhar, M. Chatterjee
• Keywords: Minor Addition, Modification, Nitrogen, Strength, Toughness

References

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