科研之友
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摘要
The annealing-induced grain growth behaviour and the transient high-heat loading performance of several W grades, including laboratory fine-grained W, oxide dispersion strengthened (ODS) W and commercial W, were measured and compared. The results show that the starting temperature causing grain growth for pure W (both laboratory fine-grained W and commercial W) is not very high, about 1300 degrees C. The finer the initial grain size of pure W, the stronger the grain growth after annealing at high temperature. But for the pure W with a very fine initial grain size, the grain size after high-temperature annealing is still not very coarse; it is less than that of commercial W. For the ODS W, only slight grain growth occurred even after annealing at a temperature of 1900 degrees C. Transient high-heat loading tests show that the surfaces of fine-grained W and ODS W tend to surface melting. For fine-grained pure tungsten, this is attributed to the low material density, which leads to a relatively bad heat transfer to the bulk and, for the ODS W, to a lower melting point of the oxide phase.
