Dummy-Bar Head 鋼材의 材質向上 = Improvement in the Quality of Steel for Dummy-Bar Head

다국어 초록 (Multilingual Abstract)

Dummy-Bar Head is used for continuous casting equipment. It is heated up at high temperature and cooled down repeatedly in using. Then the thermal extension by thermal stress and high temperature oxidation occur to it. This easily results in heating damage because Head, contact with melting metal, appears in micro-crack and tension force. In other words, it is material that gives the greatest influence in endurance life.
The method of study is to compare and evaluate present material and improved material by the new alloy design.
In conclusion, the results are as follows :
1) I think that the following range is suitable to chemical component.
◁표 삽입▷(원문을 참조하세요)
2) Micro-crack occurs in repeated heating and cooling owing to decarburization and thermal extension. Adding carbide stability elements-Cr, Mn, and V-shows martensite and less micro-crack.
3) Dummy-Bar Head is a large cast steel, An effective heat treatment condition is to heat step by step and to cool by force at 880℃. After that, It is effective to cool at 600∼680℃.
4) Improved product maintains the even hardness value. And impact value is over three times higher than present product for repeated heating and cooling.
5) The transition range over the fracture toughness value has smaller in improved product than present product for repeated heating and cooling. Through the fracture toughness evaluation, the characteristics of change is evaluated in materials. And we can make the predictable criteria of life with Refrica method.
According to the analysis and investigation of the real condition is use, the improved product is accomplished in optimal alloying design and product processing, and satifies the required condition. I think that it is widely used as proper materials to a higher temperature concerning the economy.