The effect of La on inclusions and fracture toughness of 40CrNi2Si2MoVA steel was investigated via the optical microscope,scanning electron microscope,image software and electronic universal testing machine.The result...The effect of La on inclusions and fracture toughness of 40CrNi2Si2MoVA steel was investigated via the optical microscope,scanning electron microscope,image software and electronic universal testing machine.The results reveal that the inclusions in steel without La are mainly MnS and Al_(2)O_(3)–MnS,while the inclusions in steels with La primarily contain La–O–S,La–S and other rare earth complex inclusions contain P and As.La–O–S and La–S are formed under the steelmaking temperature and act as the nucleation core of rare earth complex inclusions containing P and As.According to the segregation model,La–O–S–P–As and La–S–P–As are formed through chemical reactions during the solidification stage.As La content in steels increases from 0 to 0.032 mass%,the average spacing of inclusions is gradually increased from 5.28 to 15.91μm.The volume fraction of inclusions in steels containing less than 0.018 mass%La approaches 0.006%;however,it is significantly improved to 0.058%when La content is increased to 0.032 mass%.With the increase in La content,the fracture toughness is firstly improved from 63.1 to 80.0 MPa m^(1/2)due to the increase in average spacing of inclusions and then decreases to 69.6 MPa m^(1/2)owing to the excessive increase in volume fraction of inclusions.The optimal fracture toughness is found in 40CrNi2Si2MoVA steel with 0.018 mass%La.展开更多
为了预测机械加工及喷丸强化后40CrNi2Si2MoVA钢试样在室温下的旋转弯曲疲劳寿命,结合商用有限元软件ABAQUS和疲劳寿命分析软件FE-SAFE对不同数值计算方法的适用性及准确性进行比较,提出了喷丸强化40CrNi2Si2MoVA钢的寿命预测经验公式...为了预测机械加工及喷丸强化后40CrNi2Si2MoVA钢试样在室温下的旋转弯曲疲劳寿命,结合商用有限元软件ABAQUS和疲劳寿命分析软件FE-SAFE对不同数值计算方法的适用性及准确性进行比较,提出了喷丸强化40CrNi2Si2MoVA钢的寿命预测经验公式。结果表明:对于机械加工试样,选择"Brown-Miller"算法和表面残余应力用于计算可获得比较准确的预测结果;对于喷丸强化试样,高应力水平下也可选用"Brown-Miller"算法及表面残余应力,而低应力水平下则应改用"Stress-based Brown Miller"算法及最大残余应力。基于上述两种方法提出的经验公式:σmax=–64.378·lgN+1449.268,可改善40CrNi2Si2MoVA钢喷丸强化试样疲劳寿命预测的准确性。展开更多
基金the National Natural Science Foundation of China(Nos.U1760114 and U1760206).
文摘The effect of La on inclusions and fracture toughness of 40CrNi2Si2MoVA steel was investigated via the optical microscope,scanning electron microscope,image software and electronic universal testing machine.The results reveal that the inclusions in steel without La are mainly MnS and Al_(2)O_(3)–MnS,while the inclusions in steels with La primarily contain La–O–S,La–S and other rare earth complex inclusions contain P and As.La–O–S and La–S are formed under the steelmaking temperature and act as the nucleation core of rare earth complex inclusions containing P and As.According to the segregation model,La–O–S–P–As and La–S–P–As are formed through chemical reactions during the solidification stage.As La content in steels increases from 0 to 0.032 mass%,the average spacing of inclusions is gradually increased from 5.28 to 15.91μm.The volume fraction of inclusions in steels containing less than 0.018 mass%La approaches 0.006%;however,it is significantly improved to 0.058%when La content is increased to 0.032 mass%.With the increase in La content,the fracture toughness is firstly improved from 63.1 to 80.0 MPa m^(1/2)due to the increase in average spacing of inclusions and then decreases to 69.6 MPa m^(1/2)owing to the excessive increase in volume fraction of inclusions.The optimal fracture toughness is found in 40CrNi2Si2MoVA steel with 0.018 mass%La.
文摘为了预测机械加工及喷丸强化后40CrNi2Si2MoVA钢试样在室温下的旋转弯曲疲劳寿命,结合商用有限元软件ABAQUS和疲劳寿命分析软件FE-SAFE对不同数值计算方法的适用性及准确性进行比较,提出了喷丸强化40CrNi2Si2MoVA钢的寿命预测经验公式。结果表明:对于机械加工试样,选择"Brown-Miller"算法和表面残余应力用于计算可获得比较准确的预测结果;对于喷丸强化试样,高应力水平下也可选用"Brown-Miller"算法及表面残余应力,而低应力水平下则应改用"Stress-based Brown Miller"算法及最大残余应力。基于上述两种方法提出的经验公式:σmax=–64.378·lgN+1449.268,可改善40CrNi2Si2MoVA钢喷丸强化试样疲劳寿命预测的准确性。
