ABSTRACT An attempt has been made to investigate, dry and cryogenic broaching of AISI 4340 steel, which is predominantly used in turbine and gear manufacturing industries. The components in these industries employ broaching for mass production, and minimal deviations are the preliminary goal. A cryogenic broaching setup was developed to conduct the experiment in pull-type broaching machining cycle. In cryogenic broaching an increase of microhardness by 4.26–18.77%, curtailment in cuttingtemperature by 46.85–65.12%, and attrition in surface roughness by 87.94–96.35% is observed in correlation with dry broaching of AISI 4340 steel. TOPSIS analysis conducted for the experimental run evaluated, cutting speed of 2.1 mm/min and depth of cut 8 mm as the close to ideal solution for dry and cryogenic broaching. In cryogenic broaching the surface morphology characteristics of the broached component are superior owing to the drop in temperature, curtailed lengths of the chips and colossal lubrication factor. This in turn causes, roughness value to drop by 54.11% in cryogenic broaching in correlation with dry broaching of AISI 4340 steel. Additionally, grain size in cryogenic broaching reduces by 10.93% and 7.72% in correlation with dry broaching and base material of the sample. With the curtailment of grain size, compressive residual factor increased by 32.43%, in cryogenic broaching in correlation with dry broaching of AISI 4340 steel. The rate of corrosion drops 34.29% in cryogenic broaching in comparison with dry broaching, this is owing to the fact of refined structure along with the reduction in grain size, and increase incompressive residual factor.

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AISI 4340钢干法低温拉削试验研究

摘要 已尝试研究 AISI 4340 钢的干式和低温拉削，该钢主要用于涡轮机和齿轮制造行业。这些行业的零部件采用拉削进行批量生产，以最小的偏差为初步目标。开发了一种低温拉削装置以在拉式拉削加工循环中进行实验。在低温拉削中，观察到与 AISI 4340 钢干拉削相关的显微硬度增加 4.26-18.77%，切削温度降低 46.85-65.12%，表面粗糙度磨损 87.94-96.35%。对所评估的实验运行进行的 TOPSIS 分析，2.1 毫米/分钟的切削速度和 8 毫米的切削深度是干法和低温拉削的接近理想的解决方案。在低温拉削中，由于温度下降、切屑长度缩短和巨大的润滑因素，拉削部件的表面形态特征是优越的。这反过来导致与 AISI 4340 钢干拉削相关的低温拉削粗糙度值下降 54.11%。此外，与干拉削和样品的基材相关，低温拉削的晶粒尺寸减小了 10.93% 和 7.72%。AISI 4340钢低温拉削与干拉削相关，随着晶粒度的减小，压缩残余因子增加了32.43%。与干拉相比，低温拉削的腐蚀率下降了34.29%，这是由于组织细化，晶粒尺寸减小，压缩残余因子增加。