The solidification microstructure of Fe_(70)Cr_(18)Mo_2Si_1B_9 single-roll quenched ribbons with dif- ferent rotating speed of roller and under different atmosphere conditions was investigated. Apart from usual crysta...The solidification microstructure of Fe_(70)Cr_(18)Mo_2Si_1B_9 single-roll quenched ribbons with dif- ferent rotating speed of roller and under different atmosphere conditions was investigated. Apart from usual crystallization by homogeneous and heterogeneous nucleation,it was found that α-iron cohnnnar grains with strong preferred orientation formed beneath free surface and that spheres of α-iron single coastal with a size of several μm up to 20μm,which have rarely been reported,appeared inside the ribbons.There was experirnental evidence suggesting that clusters of metal atoms formed from fluctuation in early undercooled liquid might play a role as pre-existed nuclei and,in fact,control the formation of amorphous for this alloy.展开更多
Cold-rolled advanced high-strength steel sheets have become the material of choice for the automotive industry because of their unique attributes of high strength and balanced mechanical properties.High-hydrogen gas j...Cold-rolled advanced high-strength steel sheets have become the material of choice for the automotive industry because of their unique attributes of high strength and balanced mechanical properties.High-hydrogen gas jet cooling and water quenching are the most commonly used ultrafast cooling technologies for producing martensite-containing high-strength steel sheets.The water quenching technology ensures the fastest industrial cooling rate of 1 000 K/s;therefore,it has the highest potential with respect to saving alloys.In this study,the water quenching of a C-Mn-containing steel sheet is simulated during continuous annealing to investigate the effect of water quenching and tempering parameters on its mechanical properties.The results reveal that at low quenching temperatures,the strength of the steel sheet decreases as the soaking temperature increases.However,at high quenching temperatures,a high soaking temperature corresponds to increased strength after quenching,regardless of whether the material was austenitized in the single austenite zone or the inter-critical zone.Therefore,a high quenching temperature always results in a high strength and a high yield ratio after quenching.Low-temperature overaging(tempering) considerably influences the yield strength and yield ratio,and the extent of this influence is correlated with the soaking temperature.展开更多
The effects of quenching temperature, cooling pattern, temper temperature andtemper times on the structure and properti-es of high speed steel (HSS) rolls have beeninvestigated. The results show that, when the quenchi...The effects of quenching temperature, cooling pattern, temper temperature andtemper times on the structure and properti-es of high speed steel (HSS) rolls have beeninvestigated. The results show that, when the quenching temperature is lower than 1050℃ thehardness of HSS increases with the quenching temperature increasing in oil cooling, but when thequenching temperature exceeds 1100℃ the hardness decreases. In the conditions of salt bath coolingand air cooling, the effect of quenching temperature on the hardness is similar to the above law,but the quenching temperature obtaining the highest hardness is higher than that in oil cooling.When the temper temperature below 350℃ the hardness of HSS has a little change, when above 475℃the hardness will increase with the temper temperature increasing, and the highest hardness isobtained at 525℃. When the temper temperature continues to increase, the hardness decreases. Twicetemper has little effect on the hardness, but three times temper decreases the hardness. HSS in aircooling has lower hardenability, oil cooling can easily produce crackle, and HSS quenching in saltbath has high harde-nability and excellent wear resistance.展开更多
文摘The solidification microstructure of Fe_(70)Cr_(18)Mo_2Si_1B_9 single-roll quenched ribbons with dif- ferent rotating speed of roller and under different atmosphere conditions was investigated. Apart from usual crystallization by homogeneous and heterogeneous nucleation,it was found that α-iron cohnnnar grains with strong preferred orientation formed beneath free surface and that spheres of α-iron single coastal with a size of several μm up to 20μm,which have rarely been reported,appeared inside the ribbons.There was experirnental evidence suggesting that clusters of metal atoms formed from fluctuation in early undercooled liquid might play a role as pre-existed nuclei and,in fact,control the formation of amorphous for this alloy.
文摘Cold-rolled advanced high-strength steel sheets have become the material of choice for the automotive industry because of their unique attributes of high strength and balanced mechanical properties.High-hydrogen gas jet cooling and water quenching are the most commonly used ultrafast cooling technologies for producing martensite-containing high-strength steel sheets.The water quenching technology ensures the fastest industrial cooling rate of 1 000 K/s;therefore,it has the highest potential with respect to saving alloys.In this study,the water quenching of a C-Mn-containing steel sheet is simulated during continuous annealing to investigate the effect of water quenching and tempering parameters on its mechanical properties.The results reveal that at low quenching temperatures,the strength of the steel sheet decreases as the soaking temperature increases.However,at high quenching temperatures,a high soaking temperature corresponds to increased strength after quenching,regardless of whether the material was austenitized in the single austenite zone or the inter-critical zone.Therefore,a high quenching temperature always results in a high strength and a high yield ratio after quenching.Low-temperature overaging(tempering) considerably influences the yield strength and yield ratio,and the extent of this influence is correlated with the soaking temperature.
文摘The effects of quenching temperature, cooling pattern, temper temperature andtemper times on the structure and properti-es of high speed steel (HSS) rolls have beeninvestigated. The results show that, when the quenching temperature is lower than 1050℃ thehardness of HSS increases with the quenching temperature increasing in oil cooling, but when thequenching temperature exceeds 1100℃ the hardness decreases. In the conditions of salt bath coolingand air cooling, the effect of quenching temperature on the hardness is similar to the above law,but the quenching temperature obtaining the highest hardness is higher than that in oil cooling.When the temper temperature below 350℃ the hardness of HSS has a little change, when above 475℃the hardness will increase with the temper temperature increasing, and the highest hardness isobtained at 525℃. When the temper temperature continues to increase, the hardness decreases. Twicetemper has little effect on the hardness, but three times temper decreases the hardness. HSS in aircooling has lower hardenability, oil cooling can easily produce crackle, and HSS quenching in saltbath has high harde-nability and excellent wear resistance.
