Singh Vasundhara, Srirangam Prakash, Roy Gour Gopal
Department of Metallurgical and Materials Engineering, IIT Kharagpur, Kharagpur 721302, India.
Warwick Manufacturing Group, University of Warwick, Coventry CV4 7AL, UK.
Materials (Basel). 2023 Mar 29;16(7):2717. doi: 10.3390/ma16072717.
EN25 steels have been found to be applicable in shafts, gears, etc., but welding of EN25 steel was performed using electron beam welding with different oscillation beam diameters varying from 2 mm to 0.5 mm. The present study reports the effect of beam oscillation on the evolution of nonmetallic inclusions, microstructures, and mechanical properties of EN25 steel. Heat input calculations showed that the application of beam oscillations resulted in significantly lower heat inputs compared to their non-oscillating counterparts. The highest fraction of the retained austenite (9.35%) was observed in a weld prepared with beam oscillation at a 2-mm oscillation diameter, and it decreased to 3.27% at an oscillating diameter of 0.5 mm, and it further reduced to 0.36% for non-oscillating beam cases. Residual stresses were compressive in the fusion zone, irrespective of beam oscillation. Beam oscillation resulted in equiaxed grain in the recenter region of the fusion zone, attributed to heat mixing and the evolution of random texture. The application of beam oscillations resulted in a significant decrease in the size of the nonmetallic inclusions to 0.1-0.5 compared to 5-20 mm in base metal. All tensile samples failed in the base metal, indicating good strength of the weld. Fusion zone hardness (250-670 HNV) and wear properties (COF 0.7 to COF 0.45) improved irrespective of with and without beam oscillation.
人们发现EN25钢可应用于轴、齿轮等部件，但EN25钢的焊接采用了电子束焊接，其振荡束直径不同，从2毫米到0.5毫米不等。本研究报告了束振荡对EN25钢中非金属夹杂物的演变、微观结构和力学性能的影响。热输入计算表明，与非振荡束相比，束振荡的应用导致热输入显著降低。在振荡直径为2毫米的束振荡焊接中观察到残余奥氏体的最高比例（9.35%），在振荡直径为0.5毫米时降至3.27%，对于非振荡束情况则进一步降至0.36%。无论束是否振荡，熔合区的残余应力均为压缩应力。束振荡导致熔合区中心区域出现等轴晶粒，这归因于热混合和随机织构的演变。与母材中5 - 20毫米的非金属夹杂物尺寸相比，束振荡的应用使非金属夹杂物尺寸显著减小至0.1 - 0.5毫米。所有拉伸试样均在母材中失效，表明焊缝强度良好。无论有无束振荡，熔合区硬度（250 - 670 HNV）和磨损性能（摩擦系数从0.7降至0.45）均有所改善。
