| 摘要 |
PURPOSE:To prevent cracking by stripping in hydrogen environment at and under high temp. and high pressure by cladding pure iron on the surface of a base material consisting of carbon steel then cladding further an austenitic stainless steel thereon by build-up welding. CONSTITUTION:An intermediate layer 2 is clad between a base material 1 and a cladding material 3 in order to decrease the diffusion of C from the material 1 side and to prevent formation of a carburized layer which is a point for initiating cracking by bond stripping in the stage of a heat treatment after welding. The material of the layer 2 in this stage may be pure iron but if there is a need for taking erosion by hydrogen into consideration for the atmosphere to be used, a material composed of a low alloy steel in which the content of only the carbon is decreased is used together with the material 1. It is also possible to add Cr and Mo which are hydrogen resistant elements to the flux during welding in the case of incorporating a build-up welding method as a method for cladding the material 1 and the layer 2. There is no difference in thermal expansion at the boundary surface of the material 1 and the layer 2 as the surfaces thereof are both ferrite and since there is no abrupt change in hydrogen solubility, this part is free from cracking by stripping. |
