Development Of BWELDY Series High Strength Tempered Steel At Baosteel

With the development of engineering machinery,high parameter,large scale and the requirement of lightweight and environmentally friendly technology progress and the deepening of the concept of mining machinery,engineering machinery,put forward the requirements of high efficiency,energy saving,mining machinery,engineering machinery,etc.to promote large-scale,lightweight,high performance development.For this purpose,as the basic mechanical structure composed of steel material,is the inevitable requirement to strengthen the development,in order to deal with the market demand,the use of high strength tempered steel system BWELDY series welding structure.In this paper,the relationship between the composition series,microstructure and strength and toughness was studied by several experiments in the laboratory.The strengthening and toughening mechanism of the structure was used to realize the low carbon high strength and high toughness.Study on the treatment process,to grasp some basic rules of high strength steel during heat treatment of quenching temperature,cooling rate and tempering temperature and time parameters on the performance of the heat treatment,find the optimal scheme and obtained some properties of quenched and tempered steel decided to experiment law,the optimum heat treatment parameters for high the strength of steel industrial production.Study on the composition and system of alloy elements,and studied the role of C,Mn,Cr,Mo,Ni,B,V etc.the effect of alloying elements on properties of quenched and tempered steel,understanding the relationship between these elements and the alloy with quenched and tempered steel composition design and heat treatment process.Laboratory experiments prove that the use of direct quenching technology can greatly improve the strength of the steel plate,direct quenching can improve the yield strength and tensile strength of 100-200MPa,because the steel strength increase,steel toughness decrease.The direct quenching steel plate has higher tempering resistance than the reheating quenching steel plate.Above the critical quenching speed,the performance of the steel plate is not affected by the cooling rate.The increase of cooling rate is beneficial to the increase of strength and toughness.Tempering temperature is the key factor affecting the properties of quenched and tempered steel.With the increase of tempering temperature,the strength decreases and the toughness increases.The B element has a significant effect on the hardenability of quenched and tempered steel,and it is the most effective and economical element to improve the hardenability of the steel plate.Mo plays an important role in improving the strength and toughness of steel plate,Cr,Mn and other elements can not completely replace Mo.Especially for the thick plate,add Mo is difficult to obtain good robust performance.Mn is superior to Cr for the hardenability and toughness of steel plate,Mn is more suitable for Mo design.V can greatly improve the strength and tempering resistance of steel plate,but will reduce the low-temperature toughness of the steel plate,so that the toughness brittle transition temperature rise.At the same time,the production and trial production and batch production of the quenched and tempered steel were successfully carried out.Through the adjustment of the production components,the stable mass production thickness specification BWELDY700Q is 10-80mm,and the low temperature impact quality grade reaches D level,E level,and its performance index can meet the European standard En10025-6.According to the change of the market,the optimization of the cost reducing component of High Strength Quenched and tempered steel was studied.