Influence of Low Temperature on the Tensile Impact Properties of Two Shipbuilding Steels

Author: Elmer, David Arthur

Year: 1948

Degree: Engineer's thesis

Advisor: Clark, Donald S.

Committee Member: Unknown, Unknown

Option: Mechanical Engineering

DOI: 10.7907/04e5-ne48

Abstract

This thesis presents the results of an investigation of the influence of temperature on the tensile impact properties of two different samples of medium steel ship plate. These samples were designated as B-10 and C-10 with 0.16 percent carbon and 0.24 percent carbon respectively. Properties of these plates have been determined by static tension tests and tension impact tests at impact velocities from 10 ft/sec to 200 ft/sec, in the range of temperatures from about 8o°F to -90°F. The results of this investigation indicate that ultimate strength is increased by low temperature at any impact velocity in this range, but that elongation and strain energy absorption are decreased at low temperatures, the greatest decrease occurring between 35°F and -40°F. The engineering critical impact velocity remains about the same or shows a slight increase with decreasing temperature, depending on the material. The impact velocity for zero strain propagation decreases vii.th decreasing temperature. Some of the specimens taken from plate C-10 failed in a brittle manner in tests at -70°F at impact velocities above 100 ft/sec, while others did not. Specimens taken from plate B-10 exhibited a ductile type fracture at all temperatures and velocities. Under conditions of tensile impact, ship plate C-10 showed greater ultimate strength, elongation, and specific strain energy than plate B-10. These test results will make possible a better estimation of the behavior of structures of this materia1 under conditions of longitudinal impact at low temperatures.

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