BFe30-1-1白铜管坯的热型连铸

【作者】 赵锋；

【导师】 黎沃光；

【作者基本信息】 广东工业大学 ， 材料加工， 2002， 硕士

【摘要】 BFe30-1-1白铜管是优秀的耐海水腐蚀管材。但落后的现有铸锭工艺和加工工艺，使综合成品率仅有25～35％，造成了材料和能源的严重浪费。 热型连铸工艺具有铸锭性能好和能实现近终形铸造的优点。研究热型连铸BFe30-1-1白铜管坯，发展铸造管坯—冷拔成型—成品的工艺模式，为材料加工研究开辟了一条新思路。 热型连铸φ4、φ8BFe30-1-1白铜杆，并利用ANSYS软件的温度场热分析功能对BFe30-1-1白铜进行了凝固特性与热型连铸参数关系的研究。结果表明，通过铸型温度、冷却距离、金属液压头等铸造参数可以控制铸型温度梯度，进而控制固+液两相区的位置和长度。当固+液两相区缩短为8mm并移出铸型出口处约0.5mm时，可以有效减小固+液两相区内的凝固枝晶与铸型之间的摩擦力，消除热裂纹，并获得表面光洁的铸锭。在此研究基础上，成功地热型连铸了φ10×2白铜管坯。热型连铸的组织为致密的定向排列的树枝晶。 在熔炼温度1300℃、铸型温度1230℃、冷却位置8mm、拉铸速度30mm/min、压头30mm时，可获得表面光洁的φ4白铜杆，其枝晶间距30～40μm。改变压头为18mm时，获得了表面光洁的φ8白铜杆，枝晶间距45～55μm。其σ_b为345～355MPa，σ0.2为119.2～130.1MPa，δ大于70％。φ10×2白铜管在压头30mm、铸型温度1200℃、冷却位置距铸型出口8mm、拉铸速度为30mm/min时，获得表面光洁的管坯，枝晶间距35～45μm。 由于热型连铸铸件的壁厚较薄，能够获得较大的凝固速度，所以铸件的微观偏析程度都比普通铸锭小得多。与普通连铸φ130铸锭相比，热型连铸φ4白铜杆Ni、Fe、Mn元素的偏析程度分别降低了45％、86％、87％；热型连铸φ8白铜杆Ni、Fe、Mn元素的偏析程度则分别降低了30％、65％、55％。 研究中发现，使用石墨坩埚、导流管及石墨铸型使合金含碳量大幅 摘要一升高至 0．15wt％。经人工海水腐蚀实验发现，热型连铸 BFe30．1＊白铜的腐蚀失重率B在横截面上平均为3．24n。－。矿仰z碑，略大于普通铸锭。在拉铸方向，腐蚀失重率平均为1．24川。－。矿删2．年，小于普通铸锭的3刀62x103glcm’·年。 综合来看，热型连铸BFe30－1＊白铜管坯是可行的，达到了预期的改善铸锭质量，生产管坯的目标，可以做进一步的工业化生产研究。更多还原

【Abstract】 BFe30-1-1 cupronickel tube is an excellent material to resist sea water corrosion. But current casting and processing technique show disadvantages that results in a yield rate of only 25-35%, and serious waste of materials and energy.Heated-mould continuous casting (OCC, Ohno continuous casting) is a near net shape manufacturing process and gives high quality. The study of heated-mould continuous casting of BFe30-l-l cupronickel tube can develop a manufacturing mode including near net shape casting tube, cold drawing and finished product. That would provide a way for material processing.04 N 08 BFe30-1-1 cupronickel rod has been cast by OCC process. The relation of solidification characteristics and casting parameters were studied by use of the ANSYS software, which has very strong function in temperature field analysis. The result show that adjusting the casting parameters, such as mould temperature> cooling distance, casting speed and metal head, etc, can control the length and location of solid+liquid(S +L) zone.Smooth surface casting without hot tear can be obtained when the S +L zone is shortened to 8mm and moved to the outside of the mold exit about 0.5mm, because friction between dendrite and mould decreases. With this process, 010X2 BFe30-l-l cupronickel tube is cast successfully. The microstructure of casting by OCC process is unidirectionally arranged dendrite.The 04 cupronickel rod of smooth surface is obtained with mould temperature of 1230 癈 .cooling distance of 8mm,casting speed of 30mm/min and metal head of 30mm. The dendrite space of the 04 rod is 30~45u m. The 08 cupronickel rod of smooth surface is obtained with otherwise the same conditions except the metal head of 18mm. The dendritespace of the 08 rod is 45 ~ 60 U m. The typical tensile strength and elongation of the rod are 345~355 MPa and 70% respectively. The o 0.2 is ranged from 119.2~ 130.1 MPa. The 010X2cupronickel tube of smooth surface is obtained with mould temperature of 1200 癈,cooling distance of 8mm,casting speed of 30mm/min and metal head of 30mm. The dendrite space of the 010X2 tube is 30~50u m.The solidification rate of the OCC casting is greater than that of the ordinary casting because the OCC casting has a much thinner thickness. So the microsegregation degree decreases greatly. The decrease of microsegregation degree of NK Fe and Mn in 04 rod is 45%, 86% and 87% less than the 0130 ordinary casting respectively. As for the 08 rod, the decrease of Ni, Fe and Mn is 30%, 65% and 55% respectively.Carbon content in this experiment increases greatly to 0.15wt% because of the use of graphite crucible, graphite trough and graphite mould. The average corrosion rate of 08 rod On longitudinal section by OCC process is 1.24X10"3g/(cm 2 * year), superior to the ordinary 0130 casting(3.062 X 10"3g/(cra 2 * year)). But On cross section, its average corrosion rate is 3.24 X 10"3g/(cm 2 * year), inferior to the ordinary 0130 casting.Generally, Heated-mold continuous casting of BFe30-l-l cupronickel tube is feasible. The targets of improving casting quality and manufacturing tube have been achieved, and industrialized production experiment can be further conducted.更多还原