TWI Industrial Member Report Summary 170/1982
By W O Dinsdale and S B Dunkerton
The toughness of flash welds in 25.4mm diameter carbon manganese steel bar to BS 2112:150M19 has been examined using the Charpy V notch impact test. A limited range of welding parameters was investigated and the welds were tested in both the as-welded and the postweld heat treated conditions.
The as-welded toughness properties were poor in comparison to the parent material, and appeared to be independent of the welding conditions. Heat treatment improved the impact strength of the weld but not to the same level as the heat treated parent material. The effect of the welding parameters on the Charpy energy became more apparent when the welds were tested in the heat treated condition. It is shown that the Charpy energy decreased with increasing upset force because the reorientation of inclusions at the interface gave a plane of weakness at the notch root. Also poor toughness properties were associated with the use of a long preheat prior to the forging stage as this resulted in a coarse microstructure at the weld.
Reference is made in this report to the toughness properties of three types of friction welds, i.e. continuous drive, orbital and inertia, produced in the same batch of steel as used for the flash welds.