Relaxation Capacity Research Articles

Stress relaxation in structural titanium alloys

1. For structural titanium alloys there are minimal stresses below which the stress does not decrease at a given annealing temperature. The original residual stresses determine the annealing time but do not affect the value of the retained stress. 2. The relaxation resistance of alloys with a coarse-grained structure is 10–35% higher than for alloys with a fine-grained structure at the temperatures tested. More intensive annealing is required to remove residual stresses in weldments than in material with a fine-grained structure. 3. The relaxation resistance increases with increasing stability and decreasing extent to which the structure is heterophase. Other conditions being equal, the relaxation capacity is highest for heterophase titanium alloys of the VT22 type, with a substantial quantity of unstable βM phase. 4. As much as 50–75% of the original stress is removed in the heating stage during annealing under the conditions tested. The heating rate has a considerable effect on stress relaxation. 5. Annealing of alloys OT4-1, VT5-1, and VT22, respectively, at 600–650°, 750–800°, and 650–675° for 0.5–1 h and zonal induction annealing of weldments at 650° for 3–10 min, 800° for 10 min, and 700° for 5 min provide almost complete elimination of residual stress.

Some experiments on powdered PrNi5 in contact with liquid 3He

We Report on two sets of measurements on powdered PrNi5 in contact with liquid 3He: low-temperature magnetic susceptibility using SQUID magnetometer techniques, and also thermal relaxation and heat capacity measurements. In addition, a demagnetization experiment using the hyperfine enhanced nuclear cooling capability of PrNi5 to cool liquid 3He to 1.1 mK is described.

The heat resistance of structural materials in modern engineering

Factors determining heat resistance and refractoriness of primarily metal powder heat-resistant compositions were considered, with special attention to the strength of the interatomic bond and possible methods of its evaluation. On the basis of calculation of the root mean square displacement of atoms in the crystal lattice of heat-resistant metals and compounds, a scheme was proposed for the arrangement of many metals, on the principle of their capacity for use as a base in production of heat-resistant alloys. In estimating heat resistance of refractory compositions, we suggested taking the indices of relaxation capacity as a basis. Technological methods were outlined for producing heat-resistant compositions by use of materials possessing especially high interatomic bond strength. The principal factors characterizing the scale-resistance of refractory compositions were defined.