Joining of cemented tungsten carbide to tool steel using Nd:YAG-laser and optical fibres

• The aim of the present work was to produce tools for powder compacting by joining cemented tungsten carbide to high-quality tool steels by laser welding. The conventional method of joining such materials is by brazing or by using adhesives (glue), both of which have disadvantages: low strength and poor positional accuracy. In the case of laser welding, the components were positioned exactly in a jig or fixture, heated to 200-300°C and finally welded by using a pulsed Nd:YAG laser giving a positional accuracy in the order of a few micrometers. The laser beam was optically split and guided by optical fibers to opposite sides of the joint greatly reducing the effect of thermal distortion. The use of optical fibers also result in a smooth energy distribution in the beam spot reducing the risk of crack formation. Compressive fatigue strength of the joined components was determined. Cross-sectioned samples were examined for microstructure, microhardness and the distribution of alloying elements in the joint zone. The weld surface was also examined for evidence of microcracking. The method described can complement conventional and vacuum brazing techniques in certain applications.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Bearbetnings-, yt- och fogningsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Manufacturing, Surface and Joining Technology (hsv//eng)

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Manufacturing Systems Engineering

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