Microstructure and properties of cutting magnesium-brass containing no lead

A new environmental friend cutting brass containing magnesium instead of lead was produced by casting, extruding and drawing. Its microstructure was observed and its mechanical, chemical and cutting properties were stutied. The results show that the global secondary particles which are brittle and soft intermetallics, distribute in grains and on grain boundries, which is helpful for improvement of cutting ability of the brass. The tensile strength, yield strength, elongation and area reduction of halfhard magnesium-brass are (550MPa,) (280MPa,) (16.30%,) (32.4%,) respectively. The cutting ability of magnesium-brass corresponds to that of lead-brass C3604 judged by the size and appearance of chips of alloy and by the cutting force. The magnesium-brass has excellent corrosion resistance.

Study on the Effect of Production Parameters and Raw Materials Used on the Mechanical Properties of Leaded Brass (CuZn40Pb2) Alloy

Leaded brass alloys used progressively in many applications such as gas valves production owing to their excellent machinability, corrosion resistance and some other specifications. However, the production processes of these alloys involve some problems appearing in the last activities of production as a result of cumulative defects of previous production processes. Therefore, the current investigation studies the effect of process parameters during casting, hot extrusion and cold drawing production stages of CuZn40Pb2 leaded brass alloy on the mechanical properties. Starting with casting process, two types of charges were used. The first charge consists of 100% recycles while the second contains 30% of pure materials such as Cu, Zn and Pb in addition to the recycles. For each production stage, alloy hardness, micro-hardness, ultimate tensile strength and elongation were examined. The results illustrated that high hardness values are obtained during casting process due to some impurities such as iron and the effect of cooling rate through solidification. The hardness values decrease during extrusion process and then rise again by cold drawing for the charge of 30% pure materials. Micro-hardness values for the fractured tensile test samples appeared higher than others due to work hardening effect. The best mechanical properties as ultimate tensile strength of CuZn40Pb2 alloy products are appeared into cold forming samples with the 30% pure material added.

Identification of Rare Earth Phase in the Deformed High Lead-Brasses

Deformed high lead-brasses have excellent machining characteristics and good mechanical and physicalproperties.They are widely used in mechanical,clock-watch and pen-making field.Especially,they are suit-able for deep-hole machining.Because of their worse hot-working characteristics,there exists trouble inproduction process.It is reported that the rare earth metals could improve the hot-rolling property,but themechanism is still unclear.

Effect of the Rare Earths on the High Temperature Properties of Deformed Leaded-Brasses

The effect of the rare earths on the high temperature properties of deformed leaded-brasses has been stu- died with the high temperature tensile test.The results show that the rare earth additives can increase elongation of alloys at high temperature,but they had little effect on the maximum flow stress.With the help of SEM. X-ray diffraction instrument,quantitative metallography analysis instrument,etc.,the effect of the rare earth elements on the mierostrueture of alloys has also been examined.

氯化物与硫酸盐浓度比对黄铜-铅电偶腐蚀的影响

以供水管道中黄铜与铅焊接的电偶连接为研究对象,探究不同氯化物与硫酸盐浓度比(CSMR)对黄铜-铅电偶腐蚀的影响。分析了黄铜-铅电偶腐蚀的金属释放量、电化学行为及腐蚀产物。结果表明,CSMR使得多电偶对中阳极极性改变。在CSMR=0~0.5时,铅锌同作为阳极;CSMR=1时锌单独作为阳极;而CSMR=∞时,铅单独作为阳极。铅的腐蚀产物为棒状的PbCO_(3)及片状的Pb_(3)(CO_(3))2(OH)2,锌的产物为板状的ZnO_(2),而铜和锡的产物分别为颗粒状Cu2O和块状SnO_(2)。当供水管道中黄铜与含铅材料电偶连接时,为减少铅的释放,建议将CSMR控制在1左右。

飞机生保系统氧气导管接头腐蚀原因分析

[目的]飞机生保系统氧气导管接头装机后多次发生腐蚀问题,为保证飞机质量安全,亟需明确其腐蚀原因。[方法]针对小平管嘴与外套螺母配合面及附近区域均出现腐蚀的现象进行了形貌、组织及成分分析,并通过模拟实验来验证腐蚀成因。[结果]确定了表面腐蚀产物为不规则及泥纹花样的Cu、Zn氧化物,且存在较高含量的K、Ca、Na异常元素。氧气导管小平管嘴沟槽处容易残留中性钾皂液,在表面浸润的情况下形成了大片不规则的钾皂残留物;其余开放表面接触过中性钾皂后,在未洗净的情况下易产生不规则及泥纹花样的Cu、Zn氧化物颗粒。另外,由于焊接后小平管嘴表层脱锌形成了疏松多孔组织,因此其表面更容易吸附钾皂成分,从而加速腐蚀。[结论]氧气导管在气密试验后表面残留中性钾皂成分是导致其腐蚀的根本原因。建议气密试验后将导管彻底洗净或更换气密试验检测剂。

无铅铋黄铜耐脱锌腐蚀性能的改性优化

本文通过对无铅铋黄铜金相组织的观察、力学性能和脱锌腐蚀的测试,研究了不同退火温度对加砷与不加砷等元素的两种无铅铋黄铜的耐脱锌腐蚀性能的影响。分析了所制备合金在两种不同热处理温度后的腐蚀行为,结果表明540℃退火状态下加砷、锡元素的无铅铋黄铜耐脱锌腐蚀性能良好。

The Kinetics of Pb Removal from Brass Scrap Using Compound Separation

2 wt% Ca was added to molten brass containing 3.2 wt% Pb. The composition and grain size of the formed Ca-Pb compound were examined in detail using SEM-EDS and XRD. This revealed that the composition of the Ca-Pb compound depends on the grain size of the liquid phase Pb and the diffusion phenomenon of the Ca in the Ca-Pb compound formed on the surface of the Pb. When the Pb has a fine grain, a compound composed only of Ca-Pb compounds is formed. When the grain size of the Pb is several μm, Ca-Pb compounds containing unreacted Pb in the center are formed. These compounds aggregate into a larger compound grain. From the evaluation of the floating force (the resultant force of the weight and buoyancy of the Ca-Pb compounds formed) and the rising terminal velocity of the Ca-Pb compound within the molten brass, it was found that the floating force and rising terminal velocity depend on the composition and grain size of the Ca-Pb compound. It was found that since Ca-Pb compounds with a floating force greater than 10-6 g ·cm/s2 have a very large rising terminal velocity, they reach the surface of the molten brass in a short time after compound formation and then continue to float on the surface of the molten brass. Thus they can be removed by skimming. The effects of the grain size of the Ca-Pb compound on the floating force and the rising terminal velocity were greater than those of the composition of the Ca-Pb compound.

Mechanism of Pb Removal from Brass Scrap by Compound Separation Using Ca and NaF

The Mechanism of Pb removal from brass scrap by compound separation using Ca and NaF addition was investigated. Because large Ca-Pb compound particles formed by Ca addition rise to the surface of the molten brass, they can be skimmed off from the molten brass. However, fine Ca-Pb compound particles remain in the molten brass because of low buoyancy. By subsequent NaF addition, the reaction between Ca-Pb compound and NaF takes place at their contact regions, resulting in the formation of solid CaF2, liquid Pb and Na gas. Pb is mainly present at the Ca-Pb compound-CaF2 interface. CaF2 acts as a binder for aggregation of fine Ca-Pb compound particles, resulting in the formation of light and large composite compounds, which rise to the surface of the molten brass. A high Pb removal rate is achieved by skimming off.

电动阀电驱动器铜套断裂原因分析

某乙烯装置甲烷再生单元电动阀门电驱动器更换磨损铜套后连续发生铜套断裂现象,采用宏观检查、硬度与冲击试验、金相检验、断口微观观察与能谱分析等方法对铜套失效原因进行分析,结果表明断裂原因是电动阀在超过关限位位置存在卡滞,电驱动器输出较大的驱动力矩,以较大应力作用在材料性能较弱的铅黄铜铜套凸缘和下部梯形螺纹上,发生了凸缘及梯形螺纹的断裂。提出了电驱动器阀门检修的要求。

β相控制法改进黄铜合金的热加工性能

通过立式半连铸方法制备了Cu-40Zn-1Pb-0.15Fe-0.03Ni双相黄铜合金,针对热轧开裂问题,采用Gleeble-3500热模拟机对合金进行圆柱体压缩试验和扁平压缩试验,研究了双相黄铜合金在变形温度为600~780℃及应变速率为0.01~10 s^(-1)的条件下的热变形行为和热轧工艺性能。通过应力-应变曲线分析得到了合金的本构方程,计算绘制了热加工图,分析了热机械加工(TMP)诱导的α-β相变对α和β相的形成和铅颗粒分布的影响,利用热加工图结合显微组织确定了合金的热变形的流变失稳区和最佳变形参数。结果表明:双相黄铜合金加工过程主要存在两个失稳区:1)变形温度为670~710℃,应变速率为2.5~10 s^(-1)的区域;2)变形温度为750~780℃,应变速率为5~10 s^(-1)的区域。在较低温区(690℃以下),合金为α+β双相组织,且随着温度升高合金中β相占比逐渐增大、α相逐渐球化;在中温区(700~750℃),合金基本为β单相组织,利于热轧加工;在高温区(750℃以上),从β相组织的晶界处生长出针状α相,容易造成合金热轧开裂。

精密结构件用铅黄铜的性能研究

精密结构件的材料常为铅黄铜,但国产铅黄铜存在加工易变形、表面粗糙、刀具损耗大等问题,造成国内市场缺口。通过金相、拉伸、氨熏和加工验证试验,对比了不同产地材料在金相组织、残余内应力和力学性能方面存在的差异,分析总结了性能良好的铅黄铜材料特点,优化了铅黄铜残余内应力检测方法,修正了早期铅黄铜加工性能的评估经验数据,为材料的改进和选用提供了方向。结果表明:精密结构件用铅黄铜的加工性能与其金相组织、残余内应力和力学性能有关,为保证加工性能优良,其铅相应该均匀弥散且平均尺寸不超过15μm,抗拉强度与伸长率之比应介于15~35 MPa/%之间;铅黄铜的残余内应力,采用氨熏实验法加裂纹显示剂的方法可清晰检测,在270℃保温4 h可有效消除残余内应力。

无铅易切削镁黄铜的组织与性能

采用熔铸、挤压、拉拔的方法生产出了以镁代铅的环保型易切削黄铜材。对易切削黄铜的微观组织进行了观察,并对其力学、化学和切削性能分别进行了研究。结果表明:镁黄铜晶内和晶间有白色和黑色的球状第二相粒子分布,该粒子为金属间化合物,具有脆而不硬的特点,对提高合金切削性能有利。半硬态镁黄铜的抗拉强度为550 MPa,屈服强度为280 MPa,延伸率为16.30%,断面收缩率为32.4%。从切削过程中切削力的大小以及切屑的形貌、大小可以判断,镁黄铜的切削性能接近于C3604铅黄铜。镁黄铜在酸中和盐中的耐蚀性均较好,比较而言耐盐性要好一些。

饮用水系统黄铜零部件无铅害化处理技术研究

研制了一种用于饮用水系统黄铜零件表面除铅的除铅溶液,并开发了与之相关的黄铜零件表面除铅工艺。X射线能谱分析证明,经表面除铅处理后的黄铜零件表面的含铅量低于标准规定值。

无铅易切削硒铋黄铜的研究

介绍了无铅易切削硒铋黄铜的制备工艺,于中频感应炉中制备了无铅易切削硒铋黄铜铸锭,并对其组织和力学性能以及抗腐蚀性进行了测定。结果表明,铋以铜铋中间合金形式在1200℃加入时,铋均匀分布在铜合金中。该工艺制备的无铅易切削硒铋黄铜具有较HPb59-1好的力学性能、机加工性能和抗脱锌腐蚀性能。通过物相与组织形貌分析,解释了铋改善铜合金切削性能的机理。

无铅磷钙黄铜的组织与性能

通过熔铸方法,于中频感应炉中制备无铅磷钙黄铜铸锭,利用扫描电镜、电子能谱仪、电子万能试验机及卧式车床等手段,研究磷钙黄铜合金的显微组织和力学、切削及耐脱锌腐蚀性能,并结合切屑的形貌观察,分析金属间化合物对切削性能的改善作用。结果表明：磷、钙显著改变了黄铜的组织与性能,使得磷钙黄铜的组织由α相、β相和分布在晶界上及晶粒内的金属间化合物颗粒组成;无铅磷钙黄铜合金的主要成分（质量分数）为57%~60%Cu、40%Zn、0.7%P、0.5%Ca时,合金显示出优良的综合性能,其抗拉强度为362.7 MPa,伸长率为15.0%,布氏硬度为105.0HB,耐脱锌腐蚀深度为321.9μm,切削性能与铅黄铜HPb59-1相当。

稀土和硼细化处理对铸造铅黄铜组织和脱锌腐蚀性能的影响

研究了加入稀土和硼细化处理对铸造铅黄铜组织和脱锌腐蚀性能的影响。结果表明,加入稀土和硼后明显地细化了铸造铅黄铜的组织,使粗大的α、β板条状组织变成短小的片状或等轴状组织。用硼处理的组织细化效果要好于用稀土处理的效果,同时可以减轻铸造黄铜的脱锌腐蚀倾向。细化处理后壳杯试样的表面由未细化的粗糙表面变为光滑表面,结晶面组织由柱状晶变为等轴晶。加入细化剂可以明显改善黄铜抗脱锌腐蚀性能。

铋含量对黄铜脱锌腐蚀性能的影响

采用显微组织分析和脱锌腐蚀实验方法,研究了不同铋含量对黄铜的微观组织以及黄铜脱锌腐蚀性能的影响。结果表明,铋在铸态黄铜中为单质相,不固溶于基体中,主要以薄膜状存在于晶界上。在黄铜中加入铋可以明显改善黄铜的脱锌腐蚀性能,并且随着Bi含量的增加,黄铜的耐脱锌腐蚀性能增加。

无铅易切削黄铜的研究进展

随着世界各国对铅造成的污染和危害的重视,含铅黄铜的使用受到越来越多的限制,开发低成本无铅易切削黄铜迫在眉睫。本文根据无铅黄铜第三组元的选择特性,从组织结构、易切削机理、加工工艺、耐腐蚀性能四个方面综述了国内外无铅易切削黄铜合金的研究现状,并详细分析了铋、锑的凝固行为对合金显微组织和性能的影响,重点介绍了无铅易切削钙磷黄铜合金的微观组织、能谱分析结果、力学性能和切削性能,提出了当前工作中存在的问题,并对今后的研究趋势进行了展望,期待能够在无铅易切削黄铜的研究及实际应用中起到一定的指导作用。

无铅HSi76-3.2硅黄铜组织性能的研究

普通黄铜具有优良的机械性能、耐蚀性能、导电导热性能及加工性能,从而得到广泛应用.普通黄铜是含铅的铜锌合金,由于铅可损害人体骨髓造血系统和神经系统,研究无铅的环保型黄铜成为现时的主要课题.主要研究了无铅黄铜HSi76-3.2的组织和性能,对HSi76-3.2硅黄铜进行了去应力退火和再结晶退火处理,测试了不同状态HSi76-3.2硅黄铜的力学性能和切削性能,对其进行了光学显微组织观察、断口形貌、能谱等分析.结果表明,HSi76-3.2硅黄铜显微组织由深色相Cu5Si+Cu7Zn3(α)和浅色相Cu5Si+Cu5Zn4(β)及第三相γ相或Mg、Si、Ca、K、Al的氧化物等组成,再结晶退火后深色相Cu5Si+Cu7Zn3(α)中出现大量的孪晶组织.显微组织中深黑色第三相具有高硬度相,是保证HSi76-3.2材料有良好切削性能的主要因素.HSi76-3.2经不同处理后的力学性能有较大的变化,其断裂形式均为韧性断裂.HSi76-3.2是一种良好的普通黄铜的替代品.