In the present paper,controlled rolling and cooling processing was conducted by using a laboratory hot rolling mill.The influence of different processing parameters on the mechanical properties of low carbon cold forg...In the present paper,controlled rolling and cooling processing was conducted by using a laboratory hot rolling mill.The influence of different processing parameters on the mechanical properties of low carbon cold forging steel was investigated.The results show that the faster cooling after the deformation (especially in low temperature rolling conditions) leads to the refinement of the ferrite grain.The specimen exhibits very good mechanical properties owing to the finer ferrite grains.The pearlite morphologies can also affect the mechanical properties of low carbon cold forging steel.The mechanical properties increase with decreasing final cooling temperature within the range from 650℃ to 570 ℃ due to the finer interlamellar spacing of pearlite colony.The mechanical properties of the specimens with fast cooling after the conventional rolling are not only better than those of the specimens with slow cooling after low temperature rolling,but also almost similar to those of the specimens with fast cooling after low temperature rolling.It is suggested that fast cooling after high temperature rolling (the conventional rolling) process would be of important industrial value.展开更多
The effects of TMCP parameters,such as finish rolling temperature and cooling rate on the microstructure and mechanical properties of Nb-bearing spring steel were investigated by thermal simulation,quantitative metall...The effects of TMCP parameters,such as finish rolling temperature and cooling rate on the microstructure and mechanical properties of Nb-bearing spring steel were investigated by thermal simulation,quantitative metallography and tensile test.And the precipitation in Nb-bearing spring steel was analysis by electron microscopy.Experimental results indicate that the higher finish rolling temperature or the more rapid cooling rate in a given range,the less the proeutectoid ferrite content and the thinner the interlamellar spacing is.Reasonably higher finish rolling temperature followed by properly higher cooling rate is suggested to improve the mechanical properties of Nb-bearing spring steel.Micro-addition of niobium decreases the proeutectoid ferrite content and the interlamellar spacing and leads to forming degenerated pearlite.The precipitation of size range ～20-50 nm in Nb-bearing spring steel occurred at the lamellar ferrite of pearlite and the proeutectoid ferrite.展开更多
In order to improve the strength and toughness of 95CrMo steel and explore a short flow process, a direct rolling process was employed, and the effect of finishing rolling process on microstructure and mechanical prop...In order to improve the strength and toughness of 95CrMo steel and explore a short flow process, a direct rolling process was employed, and the effect of finishing rolling process on microstructure and mechanical properties was investigated. The results show that, with the decrease of finishing rolling temperature, inter-lamellar spacing in- creases, the strength as well as hardness has a general increase, and secondary cementite is distributed uniformly but represents a remarkable decrease in size. Based on Hall-Petch type equation, an effective relationship of yield strength and pearlite structure parameters was established. The correlation coefficients between the measured and calculated strength were more than 0.95, which indicated a high reliability of the relationship. By analyzing the individual strength contributions of pearlite structures, yield strength was found to have a more great dependence on pearlite inter-lamellar spacing than colony size.展开更多
文摘In the present paper,controlled rolling and cooling processing was conducted by using a laboratory hot rolling mill.The influence of different processing parameters on the mechanical properties of low carbon cold forging steel was investigated.The results show that the faster cooling after the deformation (especially in low temperature rolling conditions) leads to the refinement of the ferrite grain.The specimen exhibits very good mechanical properties owing to the finer ferrite grains.The pearlite morphologies can also affect the mechanical properties of low carbon cold forging steel.The mechanical properties increase with decreasing final cooling temperature within the range from 650℃ to 570 ℃ due to the finer interlamellar spacing of pearlite colony.The mechanical properties of the specimens with fast cooling after the conventional rolling are not only better than those of the specimens with slow cooling after low temperature rolling,but also almost similar to those of the specimens with fast cooling after low temperature rolling.It is suggested that fast cooling after high temperature rolling (the conventional rolling) process would be of important industrial value.
文摘The effects of TMCP parameters,such as finish rolling temperature and cooling rate on the microstructure and mechanical properties of Nb-bearing spring steel were investigated by thermal simulation,quantitative metallography and tensile test.And the precipitation in Nb-bearing spring steel was analysis by electron microscopy.Experimental results indicate that the higher finish rolling temperature or the more rapid cooling rate in a given range,the less the proeutectoid ferrite content and the thinner the interlamellar spacing is.Reasonably higher finish rolling temperature followed by properly higher cooling rate is suggested to improve the mechanical properties of Nb-bearing spring steel.Micro-addition of niobium decreases the proeutectoid ferrite content and the interlamellar spacing and leads to forming degenerated pearlite.The precipitation of size range ～20-50 nm in Nb-bearing spring steel occurred at the lamellar ferrite of pearlite and the proeutectoid ferrite.
基金Sponsored by National Science and Technology Pillar Program during the Twelfth Five-year Plan Period of China(2012BAE03B01)
文摘In order to improve the strength and toughness of 95CrMo steel and explore a short flow process, a direct rolling process was employed, and the effect of finishing rolling process on microstructure and mechanical properties was investigated. The results show that, with the decrease of finishing rolling temperature, inter-lamellar spacing in- creases, the strength as well as hardness has a general increase, and secondary cementite is distributed uniformly but represents a remarkable decrease in size. Based on Hall-Petch type equation, an effective relationship of yield strength and pearlite structure parameters was established. The correlation coefficients between the measured and calculated strength were more than 0.95, which indicated a high reliability of the relationship. By analyzing the individual strength contributions of pearlite structures, yield strength was found to have a more great dependence on pearlite inter-lamellar spacing than colony size.
