In August 18, 2005, the European Commission adopted a revised RoHS directive (2005/618/EC), which explicitly set up the concentration of 6 hazardous substances in homogeneous materials, the content of which is not more than 1000ppm. The RoHS directive (2002/95/EC) of the "annex Article 4 (1)" the sixth provisions are specified, when the lead as an alloying element in steel, aluminum, copper alloy, the allowable weight content can reach 0.35%, 0.4% and 4%.
Many manufacturers and applications of this kind of alloy material have different understanding. Some think, as long as the content of the alloy in the lead is not more than the RoHS directive (2002/95/EC) annex can be specified in the appendix; some believe that depending on the specific circumstances of the. To analyze this problem, we must first understand the concept of alloy elements.
Alloy elements are chemical elements that are specifically added to the metal or alloy in order to ensure that the organization structure, physical, chemical, and mechanical properties are required. Therefore, the RoHS instruction set the exemption condition is lead as an alloying element, its content in the steel, aluminum, copper alloy to allow to achieve the corresponding exemption. But when lead is used as an impurity, its concentration can not exceed 1000ppm.
In general, lead will always lower the performance of steel, or the incorporation of lead is not beneficial to the steel, at this time lead is an impurity, its weight in the steel can not exceed 1000ppm. But in special circumstances, such as in order to increase the steel cutting performance, can be added to the amount of lead in the steel, so that the chip is easy to break, and played a role in lubrication, at this time lead is as an alloying element, its weight in steel can be allowed to reach 0.35%.
In some aluminium, lead is good for its casting process and wear resistance, such as lead in aluminum alloy of sliding bearing, lead is the alloy element in aluminum, which can be reached 0.4%, while the content of lead in the presence of aluminum as impurities, the content can not exceed 1000ppm.
In copper, lead can strengthen the flow of copper liquid, increase toughness, lubrication and wear resistance. For example, lead in bronze bearing alloy, at this time, lead is added into the copper alloy elements, its weight in the copper can reach 4%; and when the lead in copper as an impurity, its content is not more than 1000ppm.
To sum up, to determine whether the lead content in the alloy can be achieved the corresponding exemption value, it is to determine whether the first lead is as an alloying element in these alloys. Taking into account the current level of industrial smelting, in general, if the industrial use of raw materials and the qualified, and to ensure that no wrong materials, and lead content detection results are relatively high (more than 1000ppm), the possibility of a wide range of exemptions.
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