The welding result is evaluated by following means. The welding
deformation is evaluated through the expansion rate εd
(εd = (d1 −d0)/d0) on the side of QCr0.5 and ZQSn6-6-3 of the
welded sample, where d0 is the diameter of the side of QCr0.5 and
ZQSn6-6-3 before pressure welding and d1 is the maximum diameter
after the welding. The welded samples are machined directly
into 5 mm diameter×25 mm long tensile samples, and then the
strength of the joint is tested on the material testing machine AG-
1/250 kN. The microstructures of the welded zone and the fracture
surface (40Cr side) are analyzed through optical microscopy and
the scanning electron microscopy (JSM-5610LV)