共查询到20条相似文献,搜索用时 140 毫秒
1.
提出了小方坯连铸高碳铬轴承钢中心偏析的形成机理。改善连铸高碳铬轴承钢的中心偏析的方法和途径有:提高连铸坯的宽厚比;减少钢中残余元素和有害元素及钢中夹杂物含量;降低和稳定过热度;合理选择拉速;二冷强度和电磁搅拌参数;采用软压下技术。小方坯连铸高碳铬轴承碳与模铸轴承钢的接触疲劳寿命比较试验表明:连铸材的质量优于模铸材。 相似文献
2.
连铸技术在五钢轴承钢上的应用与开发 总被引:5,自引:0,他引:5
通过对《小方坯连铸轴承钢的研究与开发》和《连铸轴承钢管坯的研究与开发》两个科研项目的研究,五钢开发了连铸轴承钢工艺流程及其技术,并进行了连铸和模铸轴承钢冶金质量及接触疲劳寿命试验与综合评估、连铸和模铸轴承钢冶金质量及轴承疲劳寿命试验与综合评估、轴承钢连铸和模铸管坯对制管以及其制成的套圈性能影响的试验研究等实验工作。到2004年底,累计生产连铸轴承钢29、64万吨;2004年度轴承钢连铸比超过40%。连铸轴承钢产品规格从φ50mm扩大到φ75mm。降低生产成本3711万元。《小方坯连铸轴承钢的生产方法》已获得发明专利授权。制定了连铸轴承钢专用产品标准。 相似文献
3.
4.
连铸流程取代模铸锻造生产高端轴承钢是当前的发展趋势。为了改善GCr15轴承钢200 mm×240 mm大方坯连铸中常见的中心缩孔和中心偏析问题,借助数值模拟研究连铸坯传热与凝固进程,并通过工业试验调整拉速探究末端电磁搅拌(final electromagnetic stirrer, F-EMS)和轻压下(soft reduction, SR)对连铸内部质量的协同影响机制和效果,通过低倍酸侵观察不同工艺下铸坯的横纵截面缩孔疏松和裂纹情况,通过钻屑取样检测铸坯横截面上碳偏析分布。结果表明,拉速为0.95 m/min时铸坯凝固终点仅为13.0 m,此时提升F-EMS强度且使用轻压下虽然可以改善中心缩孔,但F-EMS也将更多高浓度钢液搅入铸坯中心,由于铸坯中心熔池宽度小,对高浓度溶质的稀释作用小,熔池难以稀释这些钢液从而使得铸坯中心偏析反而加剧。而在F-EMS电流强度为540 A、SR总压下为7 mm的工艺下,拉速提升至1.2和1.4 m/min时,铸坯内弧侧都产生了压下裂纹,且由于GCr15轴承钢连铸凝固两相区较宽,拉速为1.4 m/min时铸坯在铸机上产生裂纹的压下辊处,铸坯内部裂纹敏感区... 相似文献
5.
6.
7.
基于建立的连铸中间包及结晶器内钢液混合过程的物理模型,开发了板坯连铸异钢种连浇过程混浇坯长度及成分变化模型。以某钢厂单流板坯连铸机220 mm×1560 mm断面Q235与Q335Ti钢的混浇过程为研究对象,采用水模型试验结合数值模拟确定模型的关键参数,并通过开展现场试验对混浇坯取样验证模型的准确性。结果证明:混浇坯成分取样与模型预测的成分偏差小于5%,且模型预测的混浇坯长度与人工确定的一致。故采用该模型可跟踪不同混浇工况下中间包内及铸流上钢液的混合行为,准确预测混浇坯的长度以及成分变化规律。采用该模型研究了拉速及中间包内剩余钢液质量对混交坯长度及不同浇注长度铸坯C元素质量分数变化的影响规律。发现当拉速保持不变时,中间包内剩余钢液越多,混浇坯越长;当中间包内剩余钢液质量保持不变时,拉速越大混浇坯越短。相比而言,中间包内剩余钢液质量比拉速对混浇坯长度的影响更大。另外当拉速不变时,随着中间包内剩余钢液质量的增加,C元素质量分数由0.16%变化到0.18%的速率减慢;当中间包内剩余钢液质量不变时,随着拉速的增加,C元素质量分数由0.16%变化到0.18%的速率增加。因此异钢种连浇过程,适当提高拉速以及减少中间包内剩余钢液质量,可有效减少混浇坯长度,成分变化速率降低。 相似文献
8.
9.
10.
11.
In this paper, a compensation control model of secondary cooling process of billet continuous casting for quality steel has been presented. The effects on the spray control of the various parameters such as steel superheat, casting speed, cooling water temperature and chemical component of steel were considered. The parameters of control model were determined to associate with the two‐dimensional heat transfer equation and solved by finite‐difference method. Effects of steel superheat and cooling water temperature on surface temperature, solidification structure and solidifying end point were discussed. Results indicate that steel superheat significantly affects solidification structure and solidifying end point but has a little effect on slab surface temperature. Moreover, secondary cooling water temperature affects surface temperature and solidifying end point but has a little effect on solidification structure. The surface temperature and solidifying end point can be maintain stabilized through applying the compensation control model when steel superheat and cooling water temperature vary. The models have been validated by industrial measurements. The results show that the simulations are in very good agreement with the real casting situation. 相似文献
12.
13.
Weiling Wang Cheng Ji Sen Luo Miaoyong Zhu 《Metallurgical and Materials Transactions B》2018,49(1):200-212
In order to predict the dendritic evolution during the continuous steel casting process, a simple mechanism to connect the heat transfer at the macroscopic scale and the dendritic growth at the microscopic scale was proposed in the present work. As the core of the across-scale simulation, a two-dimensional cell automaton (CA) model with a decentered square algorithm was developed and parallelized. Apart from nucleation undercooling and probability, a temperature gradient was introduced to deal with the columnar-to-equiaxed transition (CET) by considering its variation during continuous casting. Based on the thermal history, the dendritic evolution in a 4 mm × 40 mm region near the centerline of a SWRH82B steel billet was predicted. The influences of the secondary cooling intensity, superheat, and casting speed on the dendritic structure of the billet were investigated in detail. The results show that the predicted equiaxed dendritic solidification of Fe-5.3Si alloy and columnar dendritic solidification of Fe-0.45C alloy are consistent with in situ experimental results [Yasuda et al. Int J Cast Metals Res 22:15–21 (2009); Yasuda et al. ISIJ Int 51:402–408 (2011)]. Moreover, the predicted dendritic arm spacing and CET location agree well with the actual results in the billet. The primary dendrite arm spacing of columnar dendrites decreases with increasing secondary cooling intensity, or decreasing superheat and casting speed. Meanwhile, the CET is promoted as the secondary cooling intensity and superheat decrease. However, the CET is not influenced by the casting speed, owing to the adjusting of the flow rate of secondary spray water. Compared with the superheat and casting speed, the secondary cooling intensity can influence the cooling rate and temperature gradient in deeper locations, and accordingly exerts a more significant influence on the equiaxed dendritic structure. 相似文献
14.
15.
连铸工艺参数对SWRH82B小方坯内部质量的影响 总被引:1,自引:0,他引:1
分析了安钢第一炼轧厂150mm×150mm小方坯连铸机生产SWRH82B高强度预应力钢绞线用钢时连铸拉速、钢水过热度、冷却强度以及电磁搅拌等基本工艺参数对SWRH82B钢铸坯内部质量的影响,提出了在现有工艺条件下,生产SWRH82B钢最佳的连铸工艺参数。 相似文献
16.
ABSTRACTAn experimental apparatus for simulation of continuous casting process of GCr15 bearing steel billet is established. With the apparatus, the billets of diameter 140?mm are casted in various superheats and cooling conditions. The solidification macrostructure, dendrite morphology, segregation and carbide are investigated. It is shown that melting superheats and cooling conditions remarkably influence the microstructure and solute segregation. It is found that the secondary dendrite arm spacing of the steel increases with the increase of the superheat temperature, and with decrease of the cooling rate. Lower superheat with higher cooling rate promotes the refining of the microstructure. Refining equiaxed grains structure in the centre of the billet leads to lower segregation of carbon. Furthermore, with increasing cooling rates, the spacing of the pearlite laminar is refined and the precipitation of proeutectic carbides is suppressed. 相似文献
17.
18.
以低碳钢和中碳钢为研究对象,围绕不同连铸工艺参数对方坯初始凝固行为的影响,利用CA-FE耦合模型模拟实际连铸过程结晶器内方坯的初始凝固行为,考察拉速和过热度对方坯出结晶器坯壳厚度的影响,对比二者出结晶器横截面枝晶微观形貌.研究表明:过热度和拉速增加均能使出结晶器坯壳厚度下降,而拉速的影响更为显著.不同钢种在相同条件下出结晶器坯壳厚度下降梯度不同.过热度越低柱状晶越致密细小,利于提高连铸坯质量,拉速对柱状晶的影响相对较小.由于出结晶器坯壳安全厚度限制,过热度取15℃,低碳钢拉速不能超过2.2 m·min-1,中碳钢拉速不能超过2.5 m·min-1,据此针对不同钢种设计不同拉速可提高连铸效率.同时,模型结果显示低碳钢出结晶器时刻柱状晶更为发达. 相似文献
19.
通过对45#、70#钢铸坯低倍组织情况的分析以及连铸工艺参数的总结,探讨出钢水过热度、拉速、塞棒自动控制、二冷配水及电磁搅拌等连铸工艺参数对铸坯低倍组织的影响。通过对45#、70#钢中心碳偏析分析,表明随着钢中碳含量升高,连铸拉速、钢水过热度的增加,铸坯中心碳偏析有增大趋势。 相似文献