철계 합금의 비평형상태도 구축과 응착마모 거동에 미치는 변형유기마르텐사이트상변태의 영향

Abstract

Adhesive wear occurs when two nominally flat solid bodies are in sliding contact, whether lubricated or not. Adhesion (or bonding) occurs at the asperity contacts at the interface and these contacts are sheared by sliding, which may result in detachment of a fragment from one surface and attachment to the other surface. As the sliding continues, the transferred fragments may come off the surface on which they are transferred and be transferred back to the original surface, or else from loose wear particles.

To reduce the adhesive damage, using strain-induced martensitic transformation is expected to improve the adhesive wear resistance because it absorbs applied shear stress (or of applied external energy) of adhesive and lowers the damage. The phase transformation was intensively investigated in this study.

As the first step, it is needed to establish the non-equilibrium phase diagram which can predict the austenite stabilized region and austenite/martensite boundary before investigating the stain-induced martensitic transformation. This is because the phase transformation is known to be transformed from austenite to martensite phase.

As the second step of this study, based on the newly established the non-equilibrium phase diagram, several alloys were selected near the austenite/martensite boundary for investigating the effect of the strain-induced martensitic transformation on the adhesive wear resistance. In order to find out the correlation between the strain-induced martensitic transformation and the adhesive wear resistance, the critical strain energy was introduced as a parameter to evaluate the tendency of the strain-induced martensitic transformation of each alloy. Herein, the critical strain energy is defined to be the minimum energy which is required to initiate the phase transformation.