The HAZ microstructure and performance of Quenching and Tempering mode temper bead welding and general welded joints which were made on SA508-3 steel of 60 mm thickness were compared in this article. The result shows ...The HAZ microstructure and performance of Quenching and Tempering mode temper bead welding and general welded joints which were made on SA508-3 steel of 60 mm thickness were compared in this article. The result shows that tempering sorbite which has excellent overall performance was obtained in both modes. The microstructure of Quenching and Tempering mode welded joints got more fine grain. Even though the hardness of tempering bead welded joints is higher than the general one,it still meets the standards which is lower than 350 HV. The impact absorbing energy of each district of tempering bead welded joints HAZ reached 170 J,which is equal to general one.展开更多
Nucleation of acicular ferrite and its influence factors in non quenched-and-tempered steel was studied by using TEM and thermodynamic calculation. The results show that the complex particles with a center made of Ti ...Nucleation of acicular ferrite and its influence factors in non quenched-and-tempered steel was studied by using TEM and thermodynamic calculation. The results show that the complex particles with a center made of Ti oxide, Al2O3, and silicate and an outside made of a small quantity of mixture of TiN and MnS are able to act as ferrite nucleation nuclei. The acicular ferrite percentage changes little with Ti. When the oxygen content was 80 ppm, the volume percentage of acicular ferrite decreased due to an increase in allotriomorphic ferrite. The larger the cooling rate and the shorter the incubation time, the finer the titanium oxide and the higher the nucleation ratio of acicular ferrite.展开更多
The 8.8 grade non-quenched and tempered bolt steel was studied according to the process conditions of wire rod plant and customer requirments.Three types of experimental steel grades were selected.10MnSiTi Nb and 20Mn...The 8.8 grade non-quenched and tempered bolt steel was studied according to the process conditions of wire rod plant and customer requirments.Three types of experimental steel grades were selected.10MnSiTi Nb and 20Mn2VTi(N) were chosen as the formal steel after several experimemts.展开更多
10炉非调质钢49MnVS3(/%:0.46~0.48C,0.30~0.40Si,0.88~0.92Mn,0.001~0.014P,0.004~0.005S,0.09~0.10V,0.19~0.22Cr)由100 t EBT DC EAF-LF-VD-260 mm×340 mm坯连铸-Φ140~150 mm材轧制流程生产。采用兑入75%铁水,EAF前期脱磷至≤0...10炉非调质钢49MnVS3(/%:0.46~0.48C,0.30~0.40Si,0.88~0.92Mn,0.001~0.014P,0.004~0.005S,0.09~0.10V,0.19~0.22Cr)由100 t EBT DC EAF-LF-VD-260 mm×340 mm坯连铸-Φ140~150 mm材轧制流程生产。采用兑入75%铁水,EAF前期脱磷至≤0.015%P,出钢前[C]为0.20%~0.30%,精炼时加150~200kg碳化硅,控制LF精炼渣碱度2.80~2.95,(CaO)/(Al_2O_3)=1.2~1.6,VD后喂1.5 m/t钙铁线,软吹时间≥15min等工艺措施,49MnVS3钢中[N]、[H]和[O]分别为130×10^(-6)~220×10^(-6),1.2×10^(-6)~1.5×10^(-6)和5×10^(-6)~11×10^(-6),成品材晶粒度≥5级,非金属夹杂物和低倍组织均≤1.5级,组织(带状≤1级)和力学性能(R_m803~883 MPa,R^(el)517~590 MPa,A 16%~21%,A^(KU)39~99 J)均满足标准要求。展开更多
基金supported by the Key State Science and Technology Projects(Grant No.2011ZX04016-061 and No.2012ZX06004-001-001-005)
文摘The HAZ microstructure and performance of Quenching and Tempering mode temper bead welding and general welded joints which were made on SA508-3 steel of 60 mm thickness were compared in this article. The result shows that tempering sorbite which has excellent overall performance was obtained in both modes. The microstructure of Quenching and Tempering mode welded joints got more fine grain. Even though the hardness of tempering bead welded joints is higher than the general one,it still meets the standards which is lower than 350 HV. The impact absorbing energy of each district of tempering bead welded joints HAZ reached 170 J,which is equal to general one.
基金This work was financially supported by the National Natural Science Foundation of China (No.50574010)the National Doctor-ate Fund of the Ministry of Education of China (No.20060008015)
文摘Nucleation of acicular ferrite and its influence factors in non quenched-and-tempered steel was studied by using TEM and thermodynamic calculation. The results show that the complex particles with a center made of Ti oxide, Al2O3, and silicate and an outside made of a small quantity of mixture of TiN and MnS are able to act as ferrite nucleation nuclei. The acicular ferrite percentage changes little with Ti. When the oxygen content was 80 ppm, the volume percentage of acicular ferrite decreased due to an increase in allotriomorphic ferrite. The larger the cooling rate and the shorter the incubation time, the finer the titanium oxide and the higher the nucleation ratio of acicular ferrite.
文摘The 8.8 grade non-quenched and tempered bolt steel was studied according to the process conditions of wire rod plant and customer requirments.Three types of experimental steel grades were selected.10MnSiTi Nb and 20Mn2VTi(N) were chosen as the formal steel after several experimemts.
