- 期刊
直接鑄造變韌鐵系球墨鑄鐵之研究
Study on As-Cast Nodular Cast lron with Bainitic Matrix
摘要
本研究設計一種利用二段冷卻速率控制法，進行直接鑄造變韌鐵基地之球墨 鑄鐵的可行性研究。在添加Ni , Mo , Cu 三種主要合金元素，不同的合金組成情 況下配合冷卻速率，探討所得變韌鐵基地球墨鑄鐵性質之差異，及合金元素間Cu 取代Ni 的問題。 實驗結果顯示： (1)本研究成功地以直接鑄造、並控制冷卻速率之法，得到高於90﹪的變韌鐵基地的球墨鑄鐵，其成份範圍為C： 3.47-3.62wt% ； Si ：2.3-2.40wt%；Ni：0.0-3.1wt%；Mo：0.16-0.35wt%；Cu：0-0.84wt%，其抗拉強度：100 ~ 115 kgf / mm2 ，降伏強度： 90 ~ 100 kgf / mm2 ，延伸率1.5 ~ 3.0﹪。(2)石墨周圍旁生成下變韌鐵、遠離石墨區域生成上變韌鐵，碳的作用為其主要因素之一。(3)Cu 可取代Ni ，添加1﹪ Cu 相當於添加2﹪Ni所致之S曲線右移變韌鐵的變態效果。(4)添加合金元素固然有助於變韌鐵的變態生成右移，但要適當地控制熱平衡點溫度及瞬間切線斜率，才能得到理想的變韌鐵基地。
並列摘要
The purpose of this study was to explore the possibility of obtaining as-castbainitic nodular cast iron by a designed of two-stage-cooling after castings beingremoved from the mold. In order to enhance bainitic transformation, Ni-Mocombinations with varying amount were added, and the feasibility of replacing Ni bycheaper Cu was also persuaded. Optical and electron metallography, X-raydiffractometry, and mechanical testings were applied to study the cast matrix withnodularity better than 80﹪ From the experimental results, conclusions can be drawn that, (1) nodular castirons with more than 90﹪ bainitic matrix are obtainable by the two-stage-coolingprocess with C : 3.47 ~ 3.62wt% , Si： 2.30 ~ 2.40wt%, Ni： 0 ~ 3.10wt%, Mo： 0.16~ 0.35wt%, Cu： 0 ~ 0.84wt%, having tensile strengths 100 ~ 115 kgf / mm2 , yieldstrengths 90 ~ 100 kgf / mm2 , and elongation 1.5 ~ 3.0﹪ ； (2) lower bainite wasfound to appear nearby the graphite , while upper bainite away from it, the differencein carbon distribution is thought to be one of the main reasons； (3)Cu was found to beapproximately twice as effective as Ni in the enhancement of bainite formation；(4)although alloy addition is important, it was found that the way of controlling coolingprocesses is even more vital in obtaining bainitic matrix.