摘要
剪力釘用於鋼構建築及鋼架橋樑，以保證鋼構體的堅固及耐力，其品質要求重點為抗拉強度、降伏強度及延伸率；台灣業者使用SAE1018SK條鋼，用於製造剪力釘，於19mmФ線徑經常發生成品降伏強度不足問題。剪力釘製造過程係盤元經微抽後，下料再壓扁成形，由各階段半成品之拉力試驗值，顯示微抽後Y.S.急遽上昇，但壓扁後Y.S.又突然下降約7kg／mm2，以致最終產品Y.S.不足。經試驗分析及調查，證實壓扁後Y.S.下降係因鋼料壓扁後產生反向應力，而造成包辛格效應（Bauschinger effect），以致Y.S.下降。為避免發生包辛格效應造成剪力釘成品的Y.S.不足，在剪力釘冷鍛的各段成型之製程，需調整模具設計，當前段成型時，因桿部的線徑膨脹的反向應變量發生Y.S.下降，需於最後一次成型時，作強制縮減線徑之調整，使Y.S.再上升，以抵銷包辛格效應之下降值；或者增加原料的線徑，提高微抽之裁減量，使微抽後Y.S.增加，以抵銷包辛格效應之下降值。
並列摘要
Shear bolt is applied on steel bridge and steel frame building. It has become the main stream in modem architecture. The loss of yeild strength in semi-product is found during cold forming in the manufacture process. After the investigation, we found the Bauschinger effect happened owing to the reversal plastic strain of cold forming. It causes the loss of yield strength. Changing the die size in the mid-step process, especially the restriction and reduction in the diameter of last die, or increasing the size of raw material, will effectively increase the yield strength and compensate the loss of yield strength caused by the Bauschinger effect.