PARALLEL JOINED MATERIAL AND PRODUCTION THEREOF

PURPOSE:To improve the product accuracy of the parallel joined material by allowing a tensile stress to remain in the transverse central part of the low- expansion material of the parallel joined material and a compressive stress to remain in the transverse central part of the high-expansion material. CONSTITUTION:The parallel joined material 13 is formed by butting the end faces of the low-expansion metallic strip 1 and the high-expansion metallic strips 2, 3 against each other and welding the end faces by a welding torch 11. The metallic strips are welded while the elastic tensile stress larger than the elastic tensile stress of the high-expansion metallic strips 2, 3 is applied on the low-expansion metallic strip 1 by using bridle rolls 7, 8, 9, 14 via press rolls 10, 12. The tensile stress is made to remain in the transverse central part of the low-expansion material 1 of the parallel joined material 13 and the compressive stress to remain in the transverse central part of the high-expansion materials 2, 3 in such a manner. The deformation near the weld zone of the parallel joined material is decreased in this way.