Investigation of the temperature dependence of the hardness of molybdenum in the range of 20–2500°C

Conclusions

• 1. Data have been obtained on the temperature dependence of strain-hardened (cold-worked) and annealed molybdenum in the temperature range of 20–2500°C, hardness being measured at temperatures above 1800°C apparently for the first time.

• 2. It has been shown experimentally that there are two discontinuities, a low-temperature one and a high-temperature one, of the dependence of hardness on temperature, plotted in In H — T°K coordinates, of strain-hardened and annealed molybdenum.

• 3. It has been found that preliminary plastic deformation shifts the high-temperature discontinuity toward low temperatures.

• 4. It has been shown that hardness data of both strain-hardened and annealed molybdenum as a function of the absolute temperature are described by the equation H = Ae^−αT; the function has three portions with two constants A andα for each.

• 5. It has been shown that the curve of the temperature dependence of the ultimate strength of molybdenum, plotted in the coordinates lnσ_B−T°K, also has two discontinuities, a high-temperature one and a low-temperature one.

• 6. It has been found that the data of the dependence of tensile strength on absolute temperature are in good agreement with an equation of the form o_B = Be^−βT; the dependence also has three portions with two constants B and ß for each.

• 7. The analysis of the temperature dependence of hardness and ultimate strength of molybdenum, plotted in semilogarithmic coordinates, shows that on the individual portions there ought to exist close relations between the characteristics of hardness and strength of the pure metal.

• 8. On a basis of the analysis of the temperature dependence of hardness and tensile strength, linear relations have been found between the tensile strength, yield point, and hardness of molybdenum in the temperature range of 1100–2000°.