Evaluation of high temperature mechanical strength of Cr-Mo grade steel through small punch test technique

Remaining life assessment (RLA) of high temperature components calls for estimation current mechanical properties of the component material. For determination of mechanical properties of in-service components, large volumes of samples are required to be cut from components. The sample() removal warrants post-sampling repair by welding and mandatory post weld heat treatment. The time and the efforts involved in these exercises often limits the RLA to less reliable levels relying on the material's original properties at the time of fabrication leading to over prediction. Research is being carried out for estimation of mechanical properties of materials by destructive testing of miniature samples under various modes. Small punch test (SPT) technology is one such technique which has generated significant interest of the researchers. However challenges exist to establish procedure of testing and development of field implementable characteristic co-relation between SPT parameters and material properties. Though reports are available on room temperature (RT) properties on variety of materials to a great extent, studies on estimation of high temperature properties through SPT are sparingly available. An attempt has been made to develop correlations between SPT parameters and high temperature mechanical properties of Cr-Mo grade material. This paper describes salient features of the test setup developed and used for conducting test at high temperature, experimental results on one of the Cr-Mo grade material followed by development of correlation equation for estimating tensile properties. (C) 2014 Elsevier Ltd. All rights reserved.