SAE 9254彈簧鋼表面凹坑缺陷之冶金原因探討與改善

Metallurgical Procedures Improving the Surface Quality of SAE 9254 Spring Steel

10.30069/MM.201303_57(1).0010

梁聖樂(S. L. Liang)

界定 ； 衡量 ； 分析改善 ； 控制 ； Define ； Measure ； Analyze Improve ； Control

鑛冶：中國鑛冶工程學會會刊

57卷1期（2013 / 03 / 01）

104 - 114

繁體中文

由於國內汽機車彈簧業者使用SAE 9254鋼種製作汽車懸吊彈簧，表面品質要求極為嚴格。為了進一步探討影響彈簧表面凹坑不良之因素，故藉由DMAIC手法及製程批追蹤，並以ANOVA變異數檢定、SAS統計，發現剝片主要與小鋼胚表面研磨粗糙、出爐溫度、在爐時間有關，進而採取有效對策：（1）限定大鋼胚燒除，減少表面缺陷之過度研磨；（2）小鋼胚採細粒度砂輪片與低研磨壓力生產；（3）控制適當的出爐溫度及在爐時間，以抑制小鋼胚研磨痕殘留所造成之剝片。改善後，盤元表面良好比率由79%，提升至96%，彈簧凹坑不良率由改善前之10%降為0.19%，達成客戶滿意。

Motor vehicle industry uses high surface quality SAE 9254 spring steel to manufacture suspension springs.By means of DMAIC method and process tracking associated with ANOVA and SAS Statistics, we identified that billet surface grinding roughness, reheating temperature, and soaking time are three main factors causing sliver of rod surface defects. We adopted (1) bloom scarfing to reduce the excessive grinding of the surface defect; (2) fine-grained grinding with low pressure to optimize the billet grinding operation; and (3) proper reheating temperature and soaking time of the billet to minimize the sliver of residual grinding marks.With the improvements, the acceptance ratio of rod surface quality increases from 79% to 96% while the defect ratio of spring surface pits decreases from 10% to 0.19%.