感应加热弯管屈服强度和抗拉强度偏低原因分析

针对某管厂试制的弯管出现的过渡区外弧侧管体屈服强度和抗拉强度低于标准要求的情况进行了分析。对弯管取样进行了力学、化学及金相分析和试验。结果表明，弯管过渡区外弧侧管体屈服强度和抗拉强度偏低是因为该部位起始加热温度偏低（低于950 ℃），其淬火、回火后组织以铁素体居多，降低了抗拉强度，使其低于标准要求。建议弯管开始推制时，适当提高加热温度，使过渡区的力学性能达到要求。

Cause Analysis of Low Yield Strength and Tensile Strength of Induction Heating Elbow

In this paper, the situation of yield strength and tensile strength of the external arc side pipe in the transition zone of trial production bend which were below the standard requirements were analyzed.By the mechanics, chemistry and metallographic testing, the results show that the situation was because that the origin heating temperature(less than 950 ℃) was lower, the ferrite was in the majority after quenching and tempering , and the tensile strength was reduced to below the standard requirement. It was suggested that the origin heating temperature should be increased when the bend was pushed, the mechanical properties of the transition zone can meet the standards requirements.