Showing papers by "S. Sankaran published in 2010"
TL;DR: In this paper, the effect of nitrogen alloying in 316 LN stainless steel has been investigated for its low cycle fatigue properties in the temperature range 300 to 873 K. The effect of dynamic strain ageing has been evaluated as a function of nitrogen content, temperature, strain amplitude and strain rate.
42 citations
TL;DR: In this article, the authors compared the performance of N078 and N022 steels in the temperature range 300-873 K by strain controlled fatigue tests at ± 0.6% strain amplitude.
Abstract: In this paper, Low cycle fatigue (LCF) behavior of 316LN austenitic stainless steel alloyed with 0.078 and 0.22 wt% nitrogen, designated as N078 and N022 steels respectively, is compared in the temperature range 300–873 K by strain controlled fatigue tests at ± 0.6% strain amplitude. Interestingly, N022 steel showed continuous decrease in fatigue life with temperature in contrast to N078 steel which showed maximum in fatigue life at 573 K. Drastic reduction in fatigue life is observed in both the steels in the temperature range 673–873 K and has been attributed to the occurrence of dynamic strain aging. Both steels exhibited manifestations (for ex.: decrease in plastic strain and anomalous stress response with increase in temperature) corresponding to the occurrence of Dynamic Strain Ageing (DSA) in the above temperature range. Under all testing conditions, fracture surfaces revealed transgranular crack initiation and transgranular crack propagation.
7 citations
TL;DR: In this paper, a 3D probe referred to as a disector was used to estimate the true interlamellar spacing in a lamellar microstructure, which was then used to obtain the distribution of true interlinear spacing of pearlite in a microalloyed steel.
Abstract: It is well known that the interlamellar spacing controls the mechanical properties of any material with a lamellar microstructure. It is also expected, although not yet established, that varying distribution of interlamellar spacing would also influence the properties. However, the problem of determining the distribution of interlamellar spacing from metallographic observations made on single 2D sections is almost intractable. A technique to estimate the true interlamellar spacing in a lamellar microstructure, using a 3D probe referred to as a disector, has been developed. This disector technique was used to obtain the distribution of true interlamellar spacing of pearlite in a microalloyed steel. The results indicate clearly that there is a significant variation of interlamellar spacing across pearlite colonies and also within individual colonies. In addition, it was possible to determine the overall distribution of interlamellar spacing.
1 citations