Investigation of Thermophysical Properties of Three Barrel Steels

Piotr Koniorczyk,Janusz Zmywaczyk,Andrzej Dębski,Judyta Sienkiewicz,Marek Preiskorn,Mateusz Zieliński

doi:10.3390/met10050573

Piotr Koniorczyk, Janusz Zmywaczyk + Show 4 more

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https://doi.org/10.3390/met10050573

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Journal: Metals	Publication Date: Apr 28, 2020
Citations: 13	License type: CC BY 4.0

Affiliation: Military University of Technology in Warsaw

Abstract

In this paper, thermal diffusivity and heat capacity measurements were performed for three types of barrel steel, 38HMJ (1.8509), 30HN2MFA, and duplex (1.4462). Thermal diffusivity tests as a function of temperature were performed in the range of room temperature (RT) to 500 °C, and specific heat in the range of RT to 1000 °C. All tests were carried out using NETZSCH specialized measuring stands: LFA 467 light flash apparatus and DSC 404 F1 Pegasus differential scanning calorimeter. In the measurements of thermal diffusivity, the reference material Inconel 600 was used. This made it possible to determine thermal conductivity and specific heat as a function of the temperature of barrel steel. The results of specific heat tests of the 38HMJ and the 30HN2MFA steels show a ferrite–austenite phase transition in the 750–810 °C temperature range. This transition was not observed in the duplex steel.

Highlights

During the operation of small automatic arms, a rapid decrease in ballistic parameters such as muzzle velocity of the missile is noted after a short period of intense fire
If the temperature of the ferrite–austenite phase transition is exceeded in the steel under the chromium layer, structural changes occur [11]
In order to compare the results of specific heat values obtained independently using the DSC

Summary

Introduction

During the operation of small automatic arms, a rapid decrease in ballistic parameters such as muzzle velocity of the missile is noted after a short period of intense fire. It is caused by the passage of some gunpowder gases before the bullet due to the increased diameter of the barrel, resulting from degradation of the barrel duct due to the effects of hot powder gases [1,2,3]. The reduction in the volume of steel in the phase transition zone results in a network of cracks under the galvanic chromium layer [12]

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