the European Commission adopted a RoHS directiveamending resolution (2005/618/EC), clear set of 6 kinds of harmfulsubstances in homogeneous materials concentration limit lead contentof not more than 1000ppm. RoHS directive (2002/95/EC) of the annex toArticle 4 (1) the 6th of the provision indicates, when the lead as analloying element in steel, aluminum and copper alloys when its steel,aluminum, copper alloy allows the weight of content at 0.35%, 0.4% and4%.
Many of these alloys producers and users had a differentunderstanding. Some think that as long as the lead content in thealloy above does not exceed RoHS directive (2002/95/EC) exemption capspecified in the annex can be; some think that to, as the case may be.To analyze the problem, we must first understand the concept ofalloying elements.
Alloying elements are added to a metal or alloy, in order to securethe required organizational structure, physico-chemical and mechanicalproperties of chemical elements. RoHS directive setting conditions ofexemption is the lead as an alloying element, its steel, aluminum,copper alloy contents are allowed to reach the appropriate exemptionvalues. But when the lead as impurity is present, its concentration isnot more than 1000ppm. Generally lead will degrade the performance ofsteels, mixed with steel or lead is unhelpful and lead impurities, itsweight in steel content of not more than 1000ppm. But in exceptionalcircumstances, such as to increase the steel cutting performance, you can add the right amount of lead in steel, chip brittle, also played arole in lubrication, this time lead as an alloying element exists, itsweight in steel content can be allowed to 0.35%. In some aluminum andlead on the casting technique is good and wear resistance, such assliding bearing alloy of lead, at this point in the lead as analloying element exists in aluminum, its weight in aluminium contentallows 0.4%, when you lead as impurities in aluminum, the contentcannot exceed 1000ppm.
Of lead in copper and copper can be enhanced flow, increasedtoughness, lubrication and wear-resistance. Such as lead-bronzebearing alloys, lead is added as an alloying element in copper, it can reach the weight content of 4% in copper; and when lead as impurity incopper is present, its content cannot exceed 1000ppm.
In summary, to determine whether lead content in alloys can reach theexemption value, we must first determine whether the lead is asalloying elements present in these alloys. Taking into account thecurrent level of industrial smelting, in General, if qualified alloyused in industrial raw materials, and to ensure that nothing wrongwith the use of materials, and high lead content test results ofdialect (1000ppm), belonging to the scope of exemptions would have agreat chance.
