稀土易切削钢中稀土硫化物夹杂的性能与作用的研究

本文通过人工合成的Ce_2S_3和Ce_2O_2S夹杂物在室温到800℃范围内的高温显微硬度测试,并根据磨料与被磨损材料之间的相对硬度和磨料磨损程度的关系,详细讨论了稀土易切削钢中的Ce_2S_3和Ce_2O_2S夹杂对常用切削刀具磨料磨损的影响。结果表明,Ce_2S_3和Ce_2O_2S对切削刀具无明显的磨料磨损,故就此而言,优于钙易切削钢。     

低碳高硫含锡锑复合易切削钢

对复合添加少量Sn和Sb或Sn和Bi的低碳高硫易切削钢做了切削和高温热塑性实验. 结果表明:试样在长时间的高速切削条件下刀具后刀面磨损很小,其易切削性能明显优于SAE1215钢. 含Sn和Sb的钢样在750～950℃温度范围内塑性较差,在1050～1300℃范围内具有良好的塑性. 扫描电镜及能谱分析表明:钢中Sn和Sb元素在晶界、MnS夹杂物内及MnS边界处均存在;大部分的Bi元素附着在MnS夹杂物上,一部分弥散分布在钢的基体中;钢中MnS夹杂主要呈球状和纺锤状.     

稀土对硫易切削奥氏体不锈钢切削性与耐蚀性的影响

本文研究了稀土对硫易切削奥氏体不锈钢切削性能及耐蚀性的影响,结果表明,由于稀土的加入,改变了硫化物的组成和形态,并显著降低了一些氧化物夹杂(Al_2O_3,SiO_2等)对切削性能的有害影响。当稀土和硫的加入量适宜时,不仅钢的切削加工性能得到显著改善,而且在H_2SO_4,HNO_3以及3％NaCl溶液中的耐蚀性也接近甚至优于基础钢。     

15MnMoVNR钢硫化物及氧化物夹杂的研究

用光学金相及电子探针对15MnMoVNR钢非金属夹杂物进行了研究。发现在低的RE/S=(0.5～2)比值条件下,稀土元素能部份地改善硫化物形态,使球状、粒状及条状硫化物共存于钢中。电子探针分析证实,除个别情况外,粒状硫化物均为稀土硫化物(RE)_2S_3,且不含Mn、Mo、V等元素;而长条状硫化物则为MnS,而不含RE及Mo、V等元素。氧化物夹杂均为稀土氧化物。文中还讨论了夹杂物形态对钢性能的影响。为进一步改善钢的横向塑韧性,有必要提高钢中稀土元素的实际含量。     

稀土处理C-Mn钢显微组织和夹杂物演化

对稀土处理C-Mn钢的夹杂物和显微组织进行分析,统计稀土处理C-Mn钢中针状铁素体形核核心尺寸,并将稀土处理钢在不同温度下淬火,研究稀土夹杂物生成和长大过程. 实验结果表明:C-Mn钢加入少量稀土后钢中夹杂物从MnS﹢硅铝酸盐夹杂转变为La2 O2 S﹢LaAlO3 ﹢MnS﹢硅铝酸盐夹杂,尺寸得到细化,显微组织也从马氏体﹢贝氏体组织变成侧板条铁素体、针状铁素体和块状铁素体组织;稀土处理C-Mn钢中针状铁素体有效形核核心的尺寸集中在1~4μm,主要是在钢液中形成,冷却和凝固过程形成的数量较少;稀土夹杂物在钢液温度和冷却及凝固过程容易碰撞黏合长大,上浮从钢液中去除, MnS能在稀土夹杂物颗粒间析出.     

稀土铈在重轨钢液中行为特性的模型

以重轨钢液为研究对象,建立可以定量描述稀土铈在重轨钢液中行为特性的热力学模型,利用该热力学模型,可以预测在不同洁净度条件下重轨钢液中稀土赋存状态及夹杂物组成的变化规律.结果表明:重轨钢液中初始氧质量分数的增大,有利于稀土氧化物和稀土氧硫化物的析出;钢液中初始硫质量分数的增大,有利于稀土硫化物和稀土氧硫化物的析出;1783 K温度条件下重轨钢液中Ce2O3夹杂析出的必要条件为钢中氧硫的活度比大于等于0.19,Ce2S3夹杂析出的必要条件为钢中氧硫的活度比小于等于0.39,CeS夹杂向Ce2O2S夹杂转变的条件为钢中氧硫的活度比在0.53~0.96之间;随着洁净度的提高,重轨钢液中溶解态稀土的质量...     

两种易切削钢的研究

对未知工艺的两种易切削钢进行研究。采用电感耦合等离子体原子发射光谱法测定化学成分,通过金相显微镜观察其组织及夹杂物的形貌,使用扫描电镜分析其夹杂物,最后进行了力学及切削性能的测试。结果表明,两种钢均为低碳高硫易切削钢,其组织绝大部分为铁素体,夹杂物大多数为（Mn,Fe）S和硫化物包裹氧化物,少数为MnS;含碳量低、铁素体组织、长条状硫化物（夹杂物）是造成硬度低和切削性能差的主要原因。     

硫化锰夹杂物在YF45MnV钢中行为的原位观察

采用共焦激光扫描显微镜首次原位观察YF45MnV钢中MnS夹杂在连续升温过程中的变化.结果表明:在匀速加热过程中,细长条状MnS首先转变为近球状硫化物组成的串状夹杂物,然后近球状硫化物发生扩散长大,数量减少;温度增加到一定程度后,MnS夹杂发生固溶现象,其面积反而减小.     

YF45V(CaS)钢切削加工性及易切机理

通过诸项切削加工性对比实验证实。易切削非调质钢YF45V(CaS)比45钢正火态与调质态的切削性能均优越。这主要是易切型夹杂物在切削中起着应力集中源。包裹润滑及覆盖膜等作用。     

稀土处理钢中夹杂物对晶内针状铁素体形成的影响

分析了稀土处理钢中夹杂物的特征（夹杂物种类、尺寸分布和体积分数）对微观组织中针状铁素体形成的影响.结果表明,钢中夹杂物种类和体积分数对针状铁素体组织的形成非常重要.稀土氧化物（包含稀土氧硫化物）与铁素体具有低至1.9%的错配度降低针状铁素体在夹杂物表面的形核能垒,从而促使它在稀土氧化物上形核.反之,稀土硫化物与铁素体具有高达42.5%的错配度不能诱导生成针状铁素体组织.此外,微观组织中针状铁素体的体积分数随着夹杂物体积分数的增加而增大,当钢中夹杂物体积分数是9.5×10-4时其体积分数达到53%.     

Precipitation and control of BN inclusions in 42CrMo steel and their effect on machinability

The precipitation and control of boron nitrogen (BN) inclusions in 42CrMo steel were investigated and their effect on machinability was analyzed. First, the precipitation regularity of BN in 42CrMo steel was studied by theoretical calculation. Then, the machinability of the steel was investigated through contrast cutting experiments, and the composition and cooling rate of the steel were controlled to analyze the variation laws of the size, distribution, and area ratio of BN inclusions. Finally, the results were combined with the machinability of the steel to analyze the relationship among them. It is found that the machinability of the steel is mainly influenced by the diameter and quantity of BN inclusions. Fine and dispersedly distributed BN inclusions are more beneficial for the improvement in machinability of 42CrMo steel than coarse and sparse BN inclusions.     

Precipitation behavior of BN type inclusions in 42CrMo steel

Automobile crankshaft steel 42CrMo, which requires excellent machinability and mechanical properties, cannot be manufactured by traditional methods. To achieve these qualities, the formation behavior of boron nitride (BN) inclusions in 42CrMo steel was studied in this article. First, the precipitation temperature and the amount of BN type inclusions with different contents of boron and nitrogen in molten steel were calculated thermodynamically by FactSage software. Then the morphology and the size of BN type inclusions as well as the influence of cooling methods on them were investigated by scanning electron microscopy. Furthermore, the effects of cooling rate and the contents of B and N in molten steel on the morphology, size, and distribution of BN type inclusions were studied quantitatively and detailedly by directional solidification experiments. It is found that different BN inclusions in molten steel can form by controlling the cooling rate and the contents of B and N, which is important for obtaining the excellent machinability of 42CrMo steel.     

圆珠笔头用环保超易切削不锈钢的组织与性能

通过复合添加易切削元素S、Bi和Te,开发了一种圆珠笔头用新型无铅环保超易切削不锈钢,并对材料的组织和性能与同类进口材料进行了对比分析。结果表明,新研发钢中易切削相有MnS、Bi、MnTe及其所形成的复合夹杂物,夹杂物的种类、分布及力学性能与同类进口材料相似。经实际测试,该钢具有良好的切削加工性和书写使用性能,可以替代同类进口材料。     

Superior machinability of steel enhanced with BN and MnS particles

The strategy that replacing part of MnS with BN was proposed in order to decrease the sulfur content in sulfur based free-cutting steel. The effects of BN and MnS inclusions on the microstructure and machinability of the steel were systematically investigated. The results show that most of the BN and MnS inclusions exist individually in the steel and only a small amount of them are in a composite state forming either isolated particles or clusters of particles. In the case of multi-phased steel, the theoretical calculation predicts that the volume of large BN particles should be 0.7 times of the volume of large MnS particles. The machinability of this type of BN and MnS alloy steel over a wide range of cutting speeds ranging from a low speed appropriate for drilling to a high speed appropriate for turning is confirmed as being equal to or superior to that of an MnS reference steel, even though the sulfur content in the composite steel is only half that of the MnS steel. The aptitude for cutting effect of 240 ppm nitrogen and 115 ppm boron in the composite steel is demonstrated to be equivalent or even better than 1000 ppm sulfur in MnS free-cutting steel.     

易切削钢中夹杂物及锡的形态

研制了一种新型含锡易切削钢.在锡含量小于0.05%(质量分数)时,钢材具有良好的易切削性能,其力学性能也达到了国家标准.在扫描电镜下观察了钢中夹杂物和断口的形貌,利用能谱分析了夹杂物的成分.结果表明,钢中的复合夹杂物主要由氧化物和Mns组成.多数呈球形或纺锤形,在断口及夹杂物的表面上锡明显偏析.     

Inclusion variations and calcium treatment optimization in pipeline steel production

SiCa line and SiCaBaFe alloy were injected into liquid pipeline steel at the end of LF refining as calcium treatment, and samples were taken from the ladles, mould, and slabs. Analysis of Ca content and inclusions shows that Ca content in steel decreases obviously in the following process after calcium treatment; the compositions, morphology, and sizes of inclusions also vary much in the production; primary inclusions in the ladles prior to calcium treatment are mainly Al₂O₃ inclusions, but they turn to fine irregular CaS-CaO-Al₂O₃ compound inclusions after the treatment, then become fine globular CaO-Al₂O₃ inclusions in the mould, and finally change to a few larger irregular CaS-CaO-Al₂O₃ complex inclusions in the slabs. Thermodynamic study reveals that inclusion variations are related with the preferential reactions among Ca, Al₂O₃, and S and the precipitation of S in CaO-Al₂O₃ inclusions with high sulfur capacity. New evaluation standards for calcium treatment in high-grade pipeline steel were put forward according to the inclusion variations and requirements of pipeline steel on inclusion controlling, and the calcium process was studied and optimized.     

金属材料的动态静态可切削性研究及切屑的微观分析

本文将工件材料的动态和静态可切削性结合起来进行研究,通过实验分析了45号钢的不同热处理状态对可切削性的影响.同时对切削过程的切屑进行了微观分析研究,以探讨金属被切削的机理.研究表明:金属材料的动态切削特性和静态切削特性有本质不同,其大小亦有相当的差别;选择适当的热处理条件可以改善材料可切削性.     

X80管线钢微孔洞形核

利用扫描电镜和透射电镜等手段,观察了X80管线钢中的夹杂物和MA岛,获得了它们的尺寸统计特征.应用不同颈缩程度的拉伸试验,探明了X80管线钢中微孔洞萌生的机理：第一阶段微孔洞的形核是围绕钙处理夹杂物,在颈缩初期已经开始;第二阶段属高应变量阶段,此时孔洞是通过MA岛/基体界面脱离形核.通过有限元法分析了拉伸过程,确定了试样的真实应力--应变曲线,计算了钙处理夹杂物/基体界面强度和MA岛/基体界面强度.