Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels' performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano sc...

A medium Mn steel has been designed to achieve an excellent combination of strength and ductility based on the TRIP (Transformation Induced Plasticity) concept for automotive applications. Following six passes of hot rolling at 850 °C, the Fe-7.9Mn-0.14Si-0.05Al-0.07C (wt.%) steel was warm-rolled at 630 °C for seven passes and subsequently air cooled to room temperature. The sample was subseque...

High-carbon steels which are transformed into extremely fine bainite plates embedded in a matrix of carbon-enriched austenite have recently been developed, and have found commercial application in the manufacture of engineering components. However, because of the large carbon concentration, they cannot be welded and this limits the scope for their exploitation. A method is reported here by whic...

In this paper we present a walking pattern filter for Shape Memory Alloy (SMA) actuated biped robots. SMAs are known for their slow response. The actuation speed limitation can potentially lead to stability problems for biped robots. This filter adapts the human motion for a SMA biped in order to have a stable walking pattern. The Zero Moment Point (ZMP) is used as a main criterion of the filte...

Motivated by experimental observations of H. Seiner et al., we study the nucleation of austenite in a single crystal of a CuAlNi shape-memory alloy stabilized as a single variant of martensite. In the experiments the nucleation process was induced by localized heating and it was observed that, regardless of where the localized heating was applied, the nucleation points were always located at on...

In this paper, an advanced thermo-mechanical treatment was conducted on AISI 316 austenitic stainless steel. At first, three samples were rolled at the ambient temperature, the temperature of -20 ºC (dry ice and ethanol) and -196 ºC (liquid nitrogen). Then, the samples were annealed at 800 ºC in the time range of 1 to 15 minutes. In each step, the microhardness values of the samples were measur...

This paper traces the historical development of the methods, techniques, and applications related to the measurement of retained austenite by x-ray diffraction from the early 1930s to the present.

Spatially Resolved X-Ray Diffraction (SRXRD) has been used to identify a previously unobserved low temperature ferrite (δ)/austenite(γ) phase transformation in the heat affected zone (HAZ) of 2205 Duplex Stainless Steel (DSS) welds. In this “ferrite dip” transformation, the ferrite transforms to austenite in the weld HAZ at peak temperatures on the order of 750oC. The austenite then re-transfor...

During the summer of 2006, I had the opportunity to participate in an internship through the U.S. Department of Energy (DOE) at Oak Ridge National Laboratory (ORNL). ORNL is the nations largest national laboratory that is funded by the DOE. ORNL is known best for developing the technology for the atomic bomb and was a classified area for many years. Today ORNL’s research spans all areas of scie...

The metallic phases of meteorites are predominantly composed of Fe with B to 50 wtR Mi. During slow cooling (10-1 to 103°C per million years) be low 500°C three types of phase transformations take place: 1) Fe—Mi mar tensite (m2) decomposition to c2(ferrite) and y(austenite); 2) Decomposition of austenite to a so—called “cloudy border” of a and ; and 3) Partial ordering of 48 to 55 wtR Mi auste...