BEHAVIOR OF FREIGHT CAR CONSTRUCTION MATERIALS AT CRYOGENIC TEMPERATURES

The purpose of this study was to explore the action of wood and steel construction materials when impacted at low temperatures. Cooling and heating rates were also determined since these properties affect the quantity of coolant used to produce croygenic temperatures and the time available for demolition after the material has been cooled. Liquid nitrogen (B.P. 77.4 degrees K or -320.4 degrees F) was used in the study since this chemical is readily available in laboratory quantities and is less susceptible to explosion hazards than hydrogen or oxygen. The laboratory tests of thermal properties of wood and steel at cryogenic temperatures showed that both materials cool rapidly when immersed in liquid nitrogen with steel cooling about five times more rapidly than wood. These materials also heat rapidly when removed from the liquid nitrogen environment with steel having about five times the heating rate of wood. In the tests conducted, wood exhibited little change in fracture characteristics when the temperature was lowered to that of liquid nitrogen. Conversely, steel, at this temperature, shows brittle fracture properties as compared to ductile properties of steel at room temperature. Based on the tests conducted, scrapping wood freight cars by lowering the temperature to cryogenic levels would be impractical. Large quantities of relatively expensive coolant would be required to lower the car temperature which would heat rapidly as soon as the collant was removed. In this scheme of scrapping freight cars, it was thought that wood shattering would take place with heavy impact blows. The laboratory tests did not show any shattering effect of the wood at cyrogenic temperatures but it is possible that some steel shattering might occur if the impact blows were struck quickly after the car was cooled.

Media Info

  • Features: Figures;
  • Pagination: 11 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00097262
  • Record Type: Publication
  • Source Agency: Association of American Railroads
  • Report/Paper Numbers: MR-444
  • Files: TRIS
  • Created Date: Jul 29 1976 12:00AM