Abstract: The present invention provides a method of obtaining mechanical work from heat energy comprising heating a body of metal or metal alloy confined within a pressure vessel having a coefficient of volume expansion less than said body of metal or metal alloy contained therein to generate an increase in pressure within the vessel and causing the increased pressure to move a load thereby to do work.

Abstract: A method of manufacturing a manganese steel which comprises the steps of subjecting an alloy having the following composition by weight: carbon 0.9 to 1.4%; manganese 3.0 to 8.0%; chromium 1.0 to 2.5%; molybdenum 0.5 to 2.5%; silicon 0.25 to 2.0%; cobalt 1.0 to 5.0%; with the balance iron plus incidental impurities, to heating at a temperature within the range 900.degree. to 1100.degree. C. and then cooling the alloy to a temperature below 200.degree. C. to produce a wear-resistant manganese steel having a predominantly austenite content. The predominantly austenite steel may be converted to predominantly pearlite steel by a subsequent heating step at 500.degree. to 690.degree. C. for at least one hour. That predominantly pearlite steel may be hardened to a Rockwell C-scale hardness in excess of 50 by further heating step between 690.degree. to 800.degree. C. for at least 5 minutes.