N.R. Moody

Bio: N.R. Moody is an academic researcher from Sandia National Laboratories. The author has contributed to research in topics: Environmental stress fracture & Embrittlement. The author has an hindex of 1, co-authored 1 publications receiving 20 citations.

Hydrogen embrittlement of high strength steels

Abstract: This chapter reviews experimental studies of the hydrogen embrittlement of high strength steels. The focus has been on six types of steel, having distinctly different microstructures. The six steel types are the low alloy steels, high toughness secondary hardening steels such as AF1410, hot work die steels, martensitic secondary hardening stainless steels, maraging steels and precipitation strengthened martensitic stainless steels. The susceptibilities of these classes of steel to hydrogen embrittlement as measured by the effects of hydrogen on fracture initiation and subsequent crack growth are discussed when the steels are tested in hydrogen gas, when the hydrogen has been introduced by charging and when the hydrogen embrittlement is associated with stress corrosion cracking in distilled water or salt water.

A review of hydrogen embrittlement of martensitic advanced high-strength steels

Abstract: The martensitic advanced high-strength steels (MS-AHSS) are used to create fuel-efficient, crashworthy cars. Hydrogen embrittlement (HE) is an issue with high-strength steels; thus, the interaction of hydrogen with MS-AHSS needs to be studied. There are only a few published works on the HE of MS-AHSS. The current literature indicates that the HE susceptibility of MS-AHSS is affected by (i) the strength of the steel, (ii) the applied strain rate, (iii) the concentration of hydrogen, (iv) microstructure, (v) tempering, (vi) residual stress, (vii) fabrication route, (viii) inclusions, (ix) metallic coatings, and (x) specific precipitates. Some of the unresolved issues include (i) the correlation of laboratory results to service performance, (ii) establishing the conditions or factors that lead to a certain HE response, (iii) studying the effect of stress rate on HE, and (iv) a comprehensive understanding of hydrogen trapping in MS-AHSS.

The influence of microstructure on the hydrogen embrittlement susceptibility of martensitic advanced high strength steels

Abstract: This work addresses the influence of microstructure on the hydrogen embrittlement of advanced high-strength steels. With sufficient hydrogen, fracture initiates at the ultimate tensile stress, but initiation is at the specimen surface. Fracture initiation is typically intergranular, transgranular or quasi-cleavage. These micro-fracture modes suggest that planar defects are important, such as prior austenite grain boundaries and lath and block boundaries. Fracture propagation is by shear fracture indicating a major influence of hydrogen-dislocation interactions. These hydrogen assisted fractures occur at a fast rate, probably approaching the speed of sound, that is at fracture velocities greater than 1000 m/s.