抄録
Steel plates cladded by stainless steel in mid-section and C-Mn steel in surface layers (Stainless sandwich cladded steel plates), and C-Mn steel plates with ultra-fine grained surface layers (SUF steel plates) were previously developed, prototyped, and examined as brittle unstable crack arrest steel plates. Using these test results obtained at the time of development have been rearranged and evaluated at present, and the crack arrest performance against brittle unstable crack was discussed in this paper.
As a result, the following points were obtained.
1) In the case of a stainless sandwich cladded steel plate with a total thickness of 10 mm and a stainless steel layer thickness of 5 mm, even if brittle unstable cracks occur in the carbon steel layer arranged on the front and back layers, it will function effectively as a crack arrester plate at a temperature of －190℃ or higher. Brittle unstable fracture will not occur throughout the plate thickness.
2) The brittle unstable crack arresting performance of SUF steel plates with the chemical composition used for normal ship hull steel plates is almost equivalent to the upper limit of the brittle unstable crack arresting performance of general low temperature steel plates. In other words, at temperatures above －80℃, a 25 mm thick SUF steel plate is effective as a crack arrester steel plate.
