한국재료학회지 제28권 제5호 (p.286-294)

아연 및 알루미늄이 도금된 Hot-Press Forming 강의 염화물 환경 내 전기화학적 부식 및 수소확산거동

Electrochemical Corrosion and Hydrogen Diffusion Behaviors of Zn and Al Coated Hot-Press Forming Steel Sheets in Chloride Containing Environments
키워드 :
hot press forming steel,Zn coating,Al coating,corrosion,hydrogen diffusion

목차

Abstract
1. 서 론
2. 실험 방법
  2.1 시험편 준비 및 도금층 관찰
  2.2 복합가속부식평가 및 전기화학적 부식평가
  2.3 전기화학적 수소투과실험
  2.4 인장시험 후의 도금층 관찰
3. 결과 및 고찰
  3.1 도금층의 두께 및 조성
  3.2 CCT 및 전기화학적 부식실험
  3.3 전기화학적 수소투과실험
  3.4 인장응력 인가 후 도금층 관찰
4. 결 론
References

초록

Hot-press forming(HPF) steel can be applied successfully to auto parts because of its superior mechanical properties. However, its resistances to aqueous corrosion and the subsequent hydrogen embrittlement(HE) decrease significantly when the steel is exposed to corrosive environments. Considering that the resistances are greatly dependent on the properties of coating materials formed on the steel surface, the characteristics of the corrosion and hydrogen diffusion behaviors regarding the types of coating material should be clearly understood. Electrochemical polarization and impedance measurements reveal a higher corrosion potential and polarization resistance and a lower corrosion current of the Al-coating compared with Zn-coating. Furthermore, it was expected that the diffusion kinetics of the hydrogen atoms would be much slower in the Al-coating, and this would be due mainly to the much lower diffusion coefficient of hydrogen in the Al-coating with a face-centered cubic structure. The superior surface inhibiting effect of the Al-coating, however, is degraded by the formation of local cracks in the coated layer under severe stress conditions, and therefore further study will be necessary to gain a clearer understanding of the effect of cracks formed on the coated layer on the subsequent corrosion and hydrogen diffusion behaviors.