扫描速度对共析钢等离子表面淬火硬化的影响

Effect of scanning speed on plasma surface quenching of an eutectoid steel

以层流等离子弧作为热源对共析钢进行表面淬火,通过等离子表面淬火热传导的理论分析,对等离子弧扫描速度对硬化层最大硬化深度的影响进行研究。并利用电子扫描显微镜、显微硬度计等试验手段,研究了淬火硬化层的显微组织和力学性能。结果表明:层流等离子弧扫描速度越快,淬火硬化层最大硬化深度越小。得出等离子弧扫描速度与淬火硬化层最大硬化深度之间的关系,并且与实验结果相吻合。淬火硬化层组织为板条状马氏体和针状马氏体,淬火硬化层与基体的界面组织为珠光体和隐针马氏体,基体组织为珠光体。淬火硬化层硬度由共析钢基体的350 HV提高到900～1000 HV。

A process using laminar plasma as heat source for surface quenching of an eutectoid steel was studied. The influence of scanning speed of laminar plasma arc on the max depth of hardened layer was researched through theoretical analysis of heat conduction. Microstructure and mechanical properties of the hardened layer were examined by means of scanning electron microscopy and microhardness test. Results show that the max depth of hardened layer decreases with the increasing of the scanning speed. The quantitative relationship between the scanning speed and the max depth of hardened layer is obtained based on the experimental results. The hardened layer mainly consists of lath martensite and acicular martensite, microstructure of the interface of the hardened layer and base steel is composed of pearlite and cryptocrystalline martensite, and it is pearlite for the base steel. The microhardness of hardened layer increases from 350 HV of the base steel to 900 - 1000 HV.