溶接金属の靱性におよぼす窒素の影響

概要

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Effect of interstitial impurities, especially for nitrogen, on impact properties of submerged arc welded metal was investigated using a new technique through which only nitrogen content was varied. The results are summarized as follows. 1. Snoek's internal friction peak intensity of weld metal shows lower value than as normalized mild steel which comes mainly from existence of texture and short mean ferrite path. Solute nitrogen content (A wt%) is thought to be calculated as A (wt%)=7.0×Q^<-1>_<max> where Q^<-1>_<max> is Snocek's peak height. 2. Internal friction curves of weld metal are separted into four single relaxation peaks, C, N1,N3 and N4,which are thought to be carbon Snoek's peak, nitrogen Snoek's peak and N-Mn interaction peaks respectively, and deform shaped relaxationpeak, X-peak. 3. Ductility of weld metal decreases gradually as total nitrogen content increases but at low nitrogen content level this ductility dependence on nitrogen shows reverse tendency. 4. Ducitility of weld metal decreases as solute nitrogen content increases and for HT-60 specimen which varies almost proportionally. 5. The main role of nitrogen on impact properties of weld metal is thought to be that solute nitrogen and secondary solute nitrogen which interact with other impurity lattice atoms rasise frictional force of dislocation to decrease ductility of weld metal.
社団法人溶接学会の論文
1975-03-05