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How to replace the original material for the welded structure manufacturing

Ivković Djordje, Arsić Dušan, Cvetković Radica Prokić, Popović Olivera, Nikolić Ružica R., Bokuvka Otakar

Production Engineering Archives

2023

Vol. 29, Iss. 4

369-378

Due to difficult pandemic situation with COVID-19 decease, as well as due to current geopolitical circumstances in the world, we are facing the shortage of steel and therefore the impossibility of delivering the contracted products within the agreed deadlines. It is thus necessary to find suitable steel for replacement. The procedure for selecting one such steel for substituting the deficit steel 25CrMo4,for the purposes of producing a responsible welded assembly, is described in this paper. After the careful analysis, the steel 42CrMo4 was taken into consideration as a possible substitute material. Prior to applying the new selected steel, it was necessary to perform the following tests: analyze its chemical composition, determine its most important mechanical properties and evaluate its weld ability. Then, the optimal welding and heat treatment technologies were determined, so that the quality of the responsible welded structure would meet all the requirements, as the structure made of originally used steel. For the new steel, all the mentioned and some additional tests were conducted and the appropriate welding technology was prescribed. To verify the selected technology, appropriate tests were conducted on the model welded samples, the results of which are presented in this paper. Based on the analysis of the obtained results, it was concluded that the 25CrMo4 steel can be replaced by the 42CrMo4 steel, however, with the mandatory application of appropriate supplementary measures.

Influence of continuously cast bloom’s heating strategy on cracks occurence in low-alloyed Cr-Mo based steel 25CrMo4

Kvicala M., Moravka J., Jandacka P.

Inżynieria Materiałowa

2010

Vol. 31, nr 6

1433-1436

In the case of the Cr-Mo based low-alloyed steel hot rolling of square billets from round continuously cast blooms is complicated by fact that internal cracks are detected during ultrasonic inspection at the end of production process on cooling bed. Final quality of hot rolled billets is influenced especially by casting speed and overheating temperature in a tundish, heating conditions in soaking pit and hot rolling factors. In our paper it is demonstrated that for optimization of heating process before hot rolling it is necessary to respect thermophysical properties of low-alloyed Cr-Mo based steels. Improved heating plan led to statistically significantly lower occurence of central cracks in hot rolled billets with minimum financial cost increase.

Walcowanie bloków o przekroju kwadratowym stali Cr-Mo z ciągle odlewanych kęsów okrągłych jest komplikowane przez fakt, iż pęknięcia wewnętrzne są ujawniane dopiero podczas kontroli ultradźwiękowej na końcu całego procesu technologicznego. Na jakość wyjściową wyrobu walcowanego mają wpływ zwłaszcza prędkość odlewania, temperatura przegrzania stali w kadzi pośredniej, strategia grzania w piecu wgłębnym oraz warunki walcowania. Artykuł zwraca uwagę na fakt, iż strategia grzania przed walcowaniem musi uwzględniać właściwości termofizyczne stali niskostopowych Cr-Mo. Usprawniona strategia grzania prowadziła do znacznego zmniejszenia liczby pęknięć w wyrobach walcowanych przy minimalnym podwyższeniu kosztów.