Available Data on the Properties of Irons and Steels at Various Temperatures

Abstract

The authors point out that while a vast amount of test work has been carried out on the properties of ferrous metals at high and low temperatures, the information available is incomplete and unsatisfactory. They summarize effectively the information available for temperature effects on such mechanical properties as tensile strength, elongation, hardness, strength in torsion and crushing for cast irons, steels, cast steels, and malleable iron. There is invariably a loss in mechanical properties with increase in temperature, but this varies for each metal and alloy. The importance of the time factor in all tests is emphasized and short-time tests are considered as worthless by some investigators in indicating true behaviors under service conditions.

A brief note is given regarding the thermal expansion of some metals, some alloys, such as invar and the related nickel steels, departing completely from the usual laws of thermal expansion. “Growth” in cast iron with repeated heating is considered, and “semi-steel” is recommended for use in annealing ovens, rolls, fire bars and other cases where repeated heating occurs.

Chemical inertness is shown to be an important factor in the selection of metals for use at high temperatures, some alloys being more resistant to chemical change than others. Oxidation of steels is briefly studied. While it is evident that all steels weaken with considerable rise in temperature, the composition and treatment of steels may be varied to meet specific requirements, and emphasis is laid on the fact that heat-resisting alloys which are now being produced commercially have very desirable properties at very high temperatures. Many of these alloys cannot be called steels or even ferrous alloys, and in some cases are practically free from iron, but they are extremely valuable, nevertheless. Nickel-chrome-iron base alloys and copper-nickel and other non-ferrous alloys are among those shown to be promising for heat-resisting purposes. There is also a possibility of the development of coated metals for high-temperature service. Aluminum and chromium coatings are particularly promising in this regard.