Effects of Nitrogen and Carbon on Mechanical Properties of Weld-Simulated 19% Chromium Steels

概要

論文の詳細を見る
Poor toughnesses of welded high-chromium ferritic steels are due to the coarsened grain and the deteriorating effects of carbon and nitrogen impurities upon the intrinsically brittle b.c.c. materials. The control of these impurity elements is crucial for the improvement of the weldability and reduction of hot-cracking susceptibility. 19% chromium steels with various impurity levels of C : 10-800ppm and N : 30-740ppm, together with a commercial 19% Cr super ferritic, are high-temperature heat-treated either as in welding or as in various aging and cooling conditions. High temperature embrittlement is severely induced if the materials contain carbon/nitrogen impurity above 400ppm and if the materials are heated above 1100℃ and subsequently water-quenced. The embrittlement is caused by hardened microstructure du to supersaturated solution of carbon/nitrogen. A commercial 19% Cr super ferritic with Nb and Ti stabilizers is not so much affected by this embrittlement, but it suffers severe grain-boundary cracking when heated at 1350℃ and then water-quenched. This is due to the combined effects of phosphorous grain-boundary segregation and rapid grain growth at this temperature.
社団法人溶接学会の論文
1980-10-01