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。     

无铅锑黄铜轧制工艺的研究EI北大核心

在研究锑黄铜板材熔铸工艺的基础上,通过控制开坯温度、压下制度、轧制温度和退火制度,轧制出抗拉强度达到461.7MPa,延伸率可达15.67%,力学性能与铅黄铜HPb59-1相当的锑黄铜,为进一步提高无铅易切削锑黄铜的热轧提供了参考。     

环境友好无铅黄铜的研究进展及其在消费品制造中的应用

随着世界各国对消费品中铅含量的限制性技术标准和法规的颁布实施,含铅黄铜的使用受到越来越多的限制,我国作为消费品出口大国,含铅黄铜制品的出口也受到了严重影响。该文首先综述了世界主要国家对黄铜制日用消费品中铅含量限制的各种技术标准和法规;然后从无铅黄铜第三组元的选择特性出发,介绍了国内外无铅易切削黄铜的研究现状;最后对无铅易切削黄铜在消费品制造中的应用进行了展望。     

磷钙无铅黄铜及其切削变形机理

为取代铅,减轻对环境的污染,采用磷和钙共同替代铅,获得了综合性能优良的磷钙无铅黄铜铸锭.为研究磷钙无铅黄铜的切削变形机理,采用卧式车床进行了切削实验,通过扫描电镜及能谱仪对切屑组织进行研究,并结合Griffith脆性断裂理论和切削力学计算,对切屑变形过程进行了分析.结果表明:磷钙无铅黄铜切削性能优良,切屑的尺寸和形貌与HPb59-1相当;沿晶界弥散分布的金属间化合物,割断了基体组织的连续性,切削时在剪切力的作用下,金属间化合物颗粒经变形后发生断裂或脱落,甚至在切削热的作用下部分熔化,引发基体产生应力集中,萌生裂纹并致使扩展,导致刀具前面剪切区剪切带的周期形成,并向自由表面扩展成层片结构,造成切屑断裂,从而提高了磷钙无铅黄铜的切削性能;磷钙无铅黄铜的综合性能优良,其替代含铅黄铜,具有可行性.     

机械结构用无铅易切削钢的发展

常用的硫系、铅系易切削钢,冶炼时空气污染严重,且铅有毒,对人体有害.随着人们环保意识的加强,这类易切削钢的生产、使用将受到限制.因此,开发和生产低硫、无铅易切削钢是未来的重要发展方向.锡易切削钢、铋易切削钢、石墨易切削钢由于不添加对人和环境有害的元素,是一种非常友好的开发钢种.概述了锡易切削钢、铋易切削钢、石墨易切削钢这3类机械结构用无铅易切削钢的发展情况.     

铋对无铅易切削黄铜性能的影响

考察了0.3～0.9%的铋对无铅铋黄铜合金力学性能、切削性能的影响.通过力学性能的检测和切削性能的测定,表明随着铋含量的增加,合金的强度没有显著变化,延伸率降低,硬度增加,切削性能得到改善.添加了0.3%Ti的铋黄铜中,0.6%的铋含量的易切削黄铜力学性能适中,且切削性能与铅黄铜相当,具有广阔的应用前景.     

稀土元素对无铅焊料性能的影响

随着公众环保意识的增强,含铅焊料的发展和应用受到了极大的限制,研制新型的、环境友好的无铅焊料来取代传统的锡铅焊料成为近年来研究的热点,而添加微量元素合金化以获得性能优异的无铅焊料尤其受到研究者的关注。本文系统地综述了添加微量稀土元素对无铅焊料物理化学性能、显微组织、力学性能、电迁移及锡晶须生长等的影响,并对稀土元素在无铅焊料中的应用及发展趋势进行了展望。     

电子微连接高温无铅钎料的研究进展

基于环保的压力和人类健康的需求,电子产品微连接材料采用无铅钎料代替传统含铅钎料已是必然趋势。总结了新型无铅高温钎料的基本要求,重点评述了Bi基合金、Au基合金、Zn基合金和Sn-Sb基合金等几类钎料国内外研究现状,指出通过多元合金相图计算、合金化、材料复合化的方式开发成本、工艺性能均能与含铅钎料相媲美的无铅高温钎料。     

航空燃料中硫醇对铜合金的腐蚀行为

叙述了航空燃料中的硫醇，对飞机铜合金部件的腐蚀问题，研究了T2紫铜、H62黄铜、HPb59－1铅黄铜在含有不同硫醇浓度航空燃料中的腐蚀行为，及燃料的温度、硫醇的浓度、反应时间三个主要因素对其腐蚀行为的影响。并对其腐蚀机理进行了初步探讨。     

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.     

Comparative study of the parameters influencing the machinability of leaded brasses

One of the main applications of brasses is the manufacture of fluid carrying systems. The shape of the final product is usually made by means of machining the rolled or extruded standard bars, so that effective and low cost machining operations are required. Leaded brasses are extensively used when a good machinability is required.Two leaded brasses bars (CuZn39Pb3 alloy) with the same geometry but with different behaviour in saw cutting operations have been characterized in this work. Chemical composition, mechanical and microstructural properties have been studied in order to clarify the observed differences during saw cutting machining.Significant differences have been found with respect to the size and distribution of lead globules and phase volume fractions (α + β′), that have been explained due to the existence of different solidification and cooling patterns in both products; being the lead distribution the most important characteristic relative to the leaded brass cutting performance.     

Werkstoffmodell zur Berechnung der mittleren Fließspannung bleihaltiger Messinge bei hohen Temperaturen

Model for calculation the mean high temperature flow stress of leaded brasses A simple model for high temperature deformation behaviour of leaded brasses is presented. It is based on upsetting tests, which were performed on the alloys Wieland‐Z36 (CuZn36Pb2As) and Wieland‐Z38 (CuZn40Pb2). A temperature range from 600 °C to 850 °C and deformation rates between 0,1/s and 10/s were experimentally investigated. These parameters are important in practice, since they also appear during hot working of brass, for instance, during die forging. The model is verified using data of other CuZnPb‐alloys. The model describes the mean flow stress of a leaded brass as a function of temperature and deformation rate. The material is therein seen as a composite of α‐ and β‐phase. The phases have different deformation properties. The volume fractions of the phases are the most important microstructural parameters for hot working. They can be drawn from phase diagram and vary with temperature and chemical composition of the alloy. The volume fractions of the phases determine which phase dominates the deformation behaviour of the composite.     

Über den Einfluss von Werkstoffkennwerten auf das Spanbruchverhalten von bleiarmem Messing

Low‐leaded brass materials are gaining in industrial significance due to multiple national and international legislative regulations. Reducing the mass fraction of lead in brass material leads to unfavorable chip forms in machining and an increased chip volume ratio, which is a measure of their bulk volume. Cutting tests show that a certain amount of reduction in lead content can be compensated by adjusting the machining parameters feed and cutting depth. A phenomenological model for the calculation of the chip volume ratio as a function of the lead content and the machining parameters is developed. This work shows that there is no significant correlation between chip volume ratio and standardized material testing procedures such as tensile test, hardness testing or quantitative microstructural analysis.     

Microstructure and castability of lead‐free silicon brass alloys

Development of lead free brass alloys is an important subject due to the environmental demands and new regulations and standards that restrict lead contamination to decrease the toxicity. Pb‐free Si brasses are interesting alloys for this application, due to economical aspects and promising properties. In this work four Pb‐free brasses prepared with 1, 2, 3 and 4 wt% Si, based on Cu60/Zn40 alloy, are characterized. Their microstructure is examined and phases formed are identified. Castabilty indicated by fluidity and porosity is studied and correlated with the phases formed and their volume fraction.     

黄铜腐蚀速度与Cl-浓度的关系

为了定量确定黄铜腐蚀与Cl浓度的关系,对HSn70-1A、HAl77-2A两种黄铜进行静态挂片浸泡试验,并根据试验数据拟合了关系曲线.试验结果表明,在含Cl-的水溶液中HSn70-1A较HAl77-2A腐蚀严重;HSn70-1A、HAl77-2A的腐蚀速度随Cl-浓度的变化均呈三次方关系,区别在于HAl77-2A的腐蚀速度随Cl-浓度的变化较为平缓,而HSn70-1A的腐蚀速度随Cl-浓度的变化较为显著,HSn70-1A的腐蚀对Cl-较HAl77-2A更为敏感.     

Roman alloying practice

ABSTRACT

On the basis of a large number of published and unpublished analyses of Roman artifacts, the alloying traditions used in the production of a number of types or groups of objects are discussed. For each group, only a limited number of fairly well-defined alloys were used, probably depending on the manufacturing technique used, the color of the metal, and its mechanical properties. Three main types of bronze and two types of brass are identified. Leaded bronze was produced by addition of lead to a well-defined bronze and leaded gunmetal by mixing the leaded bronze with brass.     

Diffusion galvanizing of brass

Diffusion galvanizing of brasses (L-62, L-68, and LS-59-1) offers a means of producing zinc-rich diffused coatings whose microhardness is 3–4 times higher than that of a given brass. The wear resistance of surface coatings of this kind (measured against a hard steel disk under pressures of 30–450 g/mm² and at a circular speed of 1.2 m/sec) is 5–10 times higher than that of uncoated brasses.