Optimization of BI test parameters to investigate mechanical properties of Grade 92 steel

• Published in: IOP conference series. Materials Science and Engineering Vol. 346; no. 1; pp. 12069 - 12077
• Main Authors: Barbadikar, Dipika R, Vincent, S., Ballal, Atul R, Peshwe, Dilip R, Mathew, M D
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.04.2018
• Subjects: Austenitic stainless steels; ball Indentation testing; Constraint factor; Dislocation density; Indentation; indenter size effect; Martensitic stainless steels; Material properties; Materials selection; Mechanical properties; Optimization; Parameters; Power plants; Precipitates; Quality; Size effects; Strain hardening; Stress-strain curves; Tensile properties; Ultimate tensile strength; yield offset parameter; yield slope; Yield strength
• ISSN: 1757-8981; 1757-899X
• DOI: 10.1088/1757-899X/346/1/012069

The ball indentation (BI) testing is used to evaluate the tensile properties of materials namely yield strength, strength coefficient, ultimate tensile strength, and strain hardening exponent. The properties evaluated depend on a number of BI test parameters. These parameters include the material constants like yield slope (YS), constraint factor (CF), yield offset parameter (YOP). Number of loading/unloading cycles, preload, indenter size and depth of penetration of indenter also affects the properties. In present investigation the effect of these parameters on the stress-strain curve of normalized and tempered Grade 92 steel is evaluated. Grade 92 is a candidate material for power plant application over austenitic stainless steel and derives its strength from M23C6, MX precipitates and high dislocation density. CF, YS and YOP changed the strength properties considerably. Indenter size effect resulted in higher strength for smaller indenter. It is suggested to use larger indenter diameter and higher number of loading cycles for GRADE 92 steel to get best results using BI technique.