Nitrogen and nickel are regarded as the main factors effecting on mechanical properties and metalographical structure of low alloy welds. However there is different influence of those two elements on mechanical properties of welds. The influence of the variable amounts of nickel and nitrogen on impact properties of different basic electrode deposits were tested. Furthermore, on the basis of the results of the influence of the variable amounts of nitrogen and nickel on impact properties of low alloy basic electrode deposits, mathematical equations regarding those relationships have been given assuming that oxygen content and acicular ferrite in basic electrode deposits are nearly constant and amount of each is respectively 350–450 ppm of oxygen and above 700 of acicular ferrite.
The influence of nitrogen and nickel contents in weld metal deposit on impact properties was well analysed in the last 15 years [1–13]. Nitrogen is regarded as the negative element on impact toughness properties of low alloy basic electrode steel welds, meanwhile nickel has the positive influence on impact properties. Authors of the main publications present that the content of nitrogen in low alloy weld metal deposit should not be grater than 100 ppm, and that nickel content should not exceed 3%. It is observed that nickel (from 1% to 2%) in metal weld deposit gives good impact toughness properties of welds. The lowest amount of nitrogen in all weld metal gives the best impact results of metal weld deposit. Every 100 ppm of nitrogen in the ferrite ct may prove hardness of welds above 10 I-IV. The amount of nitrogen in low-carbon and low-alloy steel is limited, but in high alloy steel welds the amount of nitrogen could be sometimes even augmented to obtain optimal mechanical properties of welds.
