Abstract
In this work, we perform high accuracy measurements of thermophysical properties for the National Institute of Standards and Technology standard reference material for 316L stainless steel. As these properties can be sensitive to small changes in elemental composition even within the allowed tolerances for an alloy class, by selecting a publicly available standard reference material for study our results are particularly useful for the validation of multiphysics models of industrial metal processes. An ohmic pulse-heating system was used to directly measure the electrical resistivity, enthalpy, density, and thermal expansion as functions of temperature. This apparatus applies high current pulses to heat wire-shaped samples from room temperature to metal vaporization. The great advantage of this particular pulse-heating apparatus is the very short experimental duration of 50 upmu {{hbox {s}}}, which is faster than the collapse of the liquid wire due to gravitational forces, as well as that it prevents any chemical reactions of the hot liquid metal with its surroundings. Additionally, a differential scanning calorimeter was used to measure specific heat capacity from room temperature to around 1400 K. All data are accompanied by uncertainties according to the guide to the expression of uncertainty in measurement.
Highlights
The National Institute of Standards and Technology (NIST) standard reference material (SRM) for 316L stainless steel (1155a) has recently been used for studies of intense laser light coupling in metal to provide data for the validation of multiphysics models of industrial laser processes like welding, cutting, and additive manufacturing [1]
As enthalpy data obtained by ohmic pulse-heating apparatus (OPA) measurements start from room temperature, these data can be matched with the enthalpy data obtained from differential scanning calorimeter (DSC)
Specific heat capacity in the liquid phase obtained in our work is 7% higher than reported by Wilthan et al [14] and 8.5% higher than reported by Fukuyama et al [16]
Summary
It is assumed that the temperature of the molten weld pool cannot exceed the boiling point of stainless steel (assumed here to be 2800 K) From these curves, we derive the average thermal gradient, G, according to Figure 2 Analytical solutions to the heat transfer equation at three points along the surface of a semi-infinite body after an instantaneous heat load of 100 J are given as solid lines in a. The error bars represent the deviation that occurs due to the temperature range resulting from different values of a This range is used to determine the time-dependent relative error in the average thermal gradient, which is plotted on the right ordinate. The specific heat capacity cp;S of the sample was determined by the equation cp;SðTÞ cp;RðTÞ mR mS
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