Evaluation of Fracture Strain for Cold Drawn Thin-Walled Steel Tubes via Small Round-Bar Tensile Test
Evaluation of Fracture Strain for Cold Drawn Thin-Walled Steel Tubes via Small Round-Bar Tensile Test
复制标题
小圆棒拉伸试验评价冷拔薄壁钢管断裂应变
作者：
T. Matsuno;Tomoko Matsuda;Hiroto Shoji;M. Ohata
管材毛刺成形性的评价是寻找合适的管材汽车零部件材料的关键。为此，应评估韧性断裂部位的局部应变（断裂应变）。此外，冷拔钢管具有较强的各向异性形状组织，可能导致各向异性断裂应变行为。在此背景下，采用小圆杆拉伸试样对冷拔钢管的轴向和环向断裂应变进行了评估。同时对穿孔表面的抛光率进行了研究，以估计在线成形性检测的可能性。结果表明，与轴向应变相比，3根管材呈现出较差、几乎相同和较高的环向断裂应变，其中晶粒伸长和碳化物聚集共同作用导致环向变形超过40%。扫描电镜结果表明，微孔洞的生长和连接使碳化物渗透到延长的晶界上。在穿孔测试中，30%的断裂应变恶化导致穿孔表面的抛光率降低了4%。这一结果表明，对刺穿表面的估计可以在实际的管刺加工前发现材料缺陷。
The evaluation of tube burring formability is a crucial task for finding a suitable material for tube-based automobile parts. The local strain at the ductile fracture site (fracture strain) should be evaluated for this purpose. Moreover, a cold-drawn steel tube has a strong anisotropic shaped microstructure and possibly causes anisotropic fracture strain behavior. Based on this background, the study evaluated the axial and hoop directional fracture strains of cold-drawn steel tubes using the small round-bar tensile specimen. The burnished surface ratio on the pierced surface was also investigated for possibility estimation of in-line formability inspection. As a result, three tubes are presented with inferior, nearly the same, and superior hoop directional fracture strains compared with the axial strains, where exceeding 40% deterioration in the hoop direction occurs by a combination of grain elongation and carbide aggregation. The scanning electron micrographs suggest that the microvoid growth and linkage percolated thorough carbides on the elongated grain boundaries. For the piercing test, the 30% fracture strain deterioration resulted in a 4% decrease in the burnished surface ratio on the pierced surface. This result suggested that the estimation of the pierced surface can detect material defects before the actual tube-burring process.
DOI：
10.1016/j.jmatprotec.2009.11.014
发表时间：
2010-03-01
影响因子：
6.3
作者：
Mori, Ken-ichiro;Abe, Yohei;Suzui, Yoshio
通讯作者：
Suzui, Yoshio