A method of linear friction welding, the method being characterised by the steps of: providing a first workpiece and a second workpiece , the first workpiece comprising a first weld surface , and the second workpiece comprising a second weld surface , and at least one of the first weld surface and the second weld surface comprises a central ridge surface extending along the weld surface , the central ridge surface being flanked on either side respectively by a first surface and a second surface , the first surface subtending a first angle with the central ridge surface , and the second surface subtending a second angle with the central ridge surface , the first surface being further flanked by a third surface , and the second surface being further flanked by a fourth surface , the third surface subtending a third angle with the central ridge surface , the fourth surface subtending a fourth angle with the central ridge surface , and each of the third angle and the fourth angle being less than 90°; and positioning the first workpiece adjacent to the second workpiece , with the first weld surface being in engagement with the second weld surface ; wherein the method comprises the additional steps of: reciprocating the first workpiece and the second workpiece against one another such that at least one of the first weld surface and the second weld surface moves relative to the other of the first weld surface and the second weld surface , such that a temperature at the first and second weld surfaces (110:116) increases to create a weld interface ; and stopping the reciprocating and allowing the first workpiece and the second workpiece to cool to weld the first workpiece and the second workpiece together. providing a first workpiece and a second workpiece , the first workpiece comprising a first weld surface , and the second workpiece comprising a second weld surface , and at least one of the first weld surface and the second weld surface comprises a central ridge surface extending along the weld surface , the central ridge surface being flanked on either side respectively by a first surface and a second surface , the first surface subtending a first angle with the central ridge surface , and the second surface subtending a second angle with the central ridge surface , the first surface being further flanked by a third surface , and the second surface being further flanked by a fourth surface , the third surface subtending a third angle with the central ridge surface , the fourth surface subtending a fourth angle with the central ridge surface , and each of the third angle and the fourth angle being less than 90°; and positioning the first workpiece adjacent to the second workpiece , with the first weld surface being in engagement with the second weld surface ; reciprocating the first workpiece and the second workpiece against one another such that at least one of the first weld surface and the second weld surface moves relative to the other of the first weld surface and the second weld surface , such that a temperature at the first and second weld surfaces (110:116) increases to create a weld interface ; and stopping the reciprocating and allowing the first workpiece and the second workpiece to cool to weld the first workpiece and the second workpiece together. <EOS>