On the function of lead (Pb) in machining brass alloys
Journal article, 2022

Lead has traditionally been added to brass alloys to achieve high machinability, but the exact mechanisms at work are still debated. Lead-free brass alternatives could be developed if these mechanisms were better understood. Accordingly, machinability characteristics were investigated for two brass alloys with similar mechanical properties and phase composition, but with very different machining characteristics because one has 3 wt.% lead (CuZn38Pb3) while the other has only 0.1 wt.% (CuZn42). The effect of the lead was investigated using infrared temperature measurement, electron microscopy, secondary ion mass spectroscopy, quick-stop methods, and high-speed filming. Neither melting of lead nor its deposition on the tool rake surface takes place during machining thus confirming its limited lubrication and tribological effects. Instead, the main role of lead is to promote discontinuous chip formation. Lead deforms to flake-like shapes that act as crack initiation points when the workpiece material passes through the primary deformation zone. This effect prevents the development of stable tool–chip contact, thus lowering cutting forces, friction, and process temperature.

Machining

Chip formation

Brass alloys

Lead

Author

Jakob Johansson

Lund University

Per Alm

Seco Tools AB

Rachid M’Saoubi

Lund University

Seco Tools AB

Per Malmberg

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Jan Eric Ståhl

Lund University

V. Bushlya

Lund University

International Journal of Advanced Manufacturing Technology

0268-3768 (ISSN) 1433-3015 (eISSN)

Vol. In Press

Subject Categories

Tribology

Manufacturing, Surface and Joining Technology

Other Materials Engineering

Infrastructure

Chemical Imaging Infrastructure

DOI

10.1007/s00170-022-09205-0

More information

Latest update

5/20/2022