Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (45권3호 130-135)

The Change of Microstructures According to the Charging Amounts of Hydrogen in High Strength DP Steels and TRIP Steel

고강도 DP강과 TRIP강의 표면 수소 주입량에 따른 수소취성평가

이철치;박재우;강계명;
Lee, Chul-Chi;Park, Jae-Woo;Kang, Kae-Myung;

서울과학기술대학교 산업대학원 재료공학과;서울과학기술대학교 에너지환경대학원 신에너지공학과;서울과학기술대학교 신소재공학과;
Dept. of Materials Science and Engineering, The Graduate School of Industry & Engineering, SNUST;Dept. of New Energy Engineering, The Graduate School of Energy & Environment, SNUST;Dept. of Materials Science & Engineering, SNUST;

DOI : 10.5695/JKISE.2012.45.3.130

Abstract

Hydrogen charging was electrochemically conducted at high strength DP steels and TRIP steel with varying charging time. The penetration depths and the mechanical properties with charging conditions were investigated through the distribution of micro-hardness and the microstructural observation of the subsurface zone. The micro-Vickers hardness was measured to evaluate the hydrogen embrittlement of subsurface zone in addition to the microscope investigation. It was shown that the hydrogen amounts decreased in DP steels and TRIP steel with increasing hydrogen charging time. As shown by micro-Vickers hardness test and small punch test results, micro-Vickers hardness and SP energy for DP steels and TRIP steel decreased with increasing hydrogen charging time, for constant value of charging current density. SEM investigation results for the hydrogen contained samples showed that the major fracture behavior was brittle fracture which results in dimples on fractured surface and the size of dimples were decreased with increasing hydrogen charging time. These results indicate that hydrogen embrittlement is the major cause for the fracture of high strength steels and also micro-Vickers hardness test and small punch test is a valuable test method for hydrogen embrittlement of high strength sheet steels.

Keywords

Hydrogen charging;DP steel;TRIP steel;Hygen embrittlement;