重熔工藝對K452合金高溫拉伸性能的影響重熔工藝對K452合金高溫拉伸性能的影響Effects of re-melting processes on the tensile properties of K452 alloy at high temperature 采用不同重熔工藝制備K452合金試樣， 測試試樣在900 ℃下的拉伸性能。結果表明：當澆注溫度為1430 ℃時， 試樣的抗拉強度從410變化到 510 MPa，延伸率從 3.5 % 變化到 22 %，實驗數(shù)據(jù)較分散；試樣中O和N平均含量較高，尤其N含量達0.0028 %之多；斷口上存在大量疏松。當澆注溫度提高到1500 ℃時，拉伸性能得到提高，試樣中O和N的平均含量有所降低，斷口上疏松減小。當合金經(jīng)過1590 ℃保溫5 min的高溫凈化處理，澆注溫度仍為1500 ℃時，試樣的拉伸性能大幅度提高，O和N的平均含量明顯降低，斷口上沒有觀察到疏松，實驗數(shù)據(jù)具有較好的一致性。 A K452 alloy is a nickel-based cast superalloy having the good tensile properties at high temperature and excellent corrosion resistance. It has been applied as a blade material of engines when environmental temperature is not above 950 ℃. It is found that the tensile properties of the alloy have become more scattered and unstable although its chemical compositons are not changed. Hence, the tensile properties of the alloy were studied in order to increase its stability at high temperature and improve its applied properties. Tensile specimens were prepared using the different re-melting processes. Tensile tests were done at 900 ℃.When the pouring temperature was 1430 ℃, tensile properties were not only lower than expected, but also had great degree of dispersion, i.e., the vales of ultimate strengths changed in the range of 410 and 510 MPa, and the elongations changed in the range of 3.5 and 22 %, the average contents of O and N were the highest among three tested conditions. The highest N content was 0.0028 %. And the shrinkage area was higher than those in other two re-melting processes. When the pouring temperature was 1500 ℃, the tensile properties were improved, and their changing scopes became small, the average contents of O and N decreased, the shrinkage area decreased. When the refining temperature was 1590 ℃ and the holding time was 5 min, both average contents of O and N were decreased greatly, the shrinkage was not seen in the fracture surfaces. And the tensile properties were improved. Furthermore, their changing scopes were very small.
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