悬架簧用油淬火回火弹簧钢丝脆断原因分析

悬架簧用油淬火回火弹簧钢丝在生产、运输和贮存过程中会发生脆断 ,通过对脆断钢丝进行理化分析、金相检验和断口形貌的电子显微镜扫描分析 ,认为造成钢丝脆性断裂的直接原因是钢丝表面缺陷 (如表面裂纹、夹杂、机械碰伤等 ) ,这些缺陷在弹性弯曲和热处理残余应力的共同作用下 ,导致了裂纹的萌生、扩展 ,最终导致材料脆断 ,断口形貌的主要特征是沿晶断裂。通过对断口晶界的分析表明 ,断口晶界处并无明显杂质元素偏聚的迹象 ,可以认为高温回火脆性与钢丝脆断并无直接关系。

Cause Analyses of Brittle Fracture of Oil-tempered Spring Steel Wire for Suspension Spring

The oil-tempered spring steel wire for suspension spring happen to brittle fracture in production,storage and transporting.By analyzing mechanical properties and chemical composition and by metallography examining and fracture morphology examining with SEM,it is considered that the direct cause for briffle fracture of the wire is surface defect such as surface crack,inclusion and mechanical damage,which lead to crack to produce and expand and bring about fracture at last under the conditions of common action of elastic bending and heat treatment remain stress.The main characteristic of the fracture morphology belongs to along crystal boundary fracture.It is shown by crystal boundary analyses that there is no obvious inclusion elements partial gather at the crystal boundary,so it is considered that the high temperature temper brittleness has no direct relative to the brittle fracture of the wire.