Effects of Alloying Elements Addition on Delayed Fracture Properties of Ultra High-Strength TRIP-Aided Martensitic Steels

Abstract

To develop ultra high-strength cold stamping steels for automobile frame parts, the effects of alloying elements on hydrogen embrittlement properties of ultra high-strength low alloy transformation induced plasticity (TRIP)-aided steels with a martensite matrix (TM steels) were investigated using the four-point bending test and conventional strain rate tensile test (CSRT). Hydrogen embrittlement properties of the TM steels were improved by the alloying addition. Particularly, 1.0 mass% chromium added TM steel indicated excellent hydrogen embrittlement resistance. This effect was attributed to (1) the decrease in the diffusible hydrogen concentration at the uniform and fine prior austenite grain and packet, block, and lath boundaries; (2) the suppression of hydrogen trapping at martensite matrix/cementite interfaces owing to the suppression of precipitation of cementite at the coarse martensite lath matrix; and (3) the suppression of the hydrogen diffusion to the crack initiation sites owing to the high stability of retained austenite because of the existence of retained austenite in a large amount of the martensite–austenite constituent (M–A) phase in the TM steels containing 1.0 mass% chromium.

Effects of Residual Stress on Hydrogen Embrittlement of a Stretch-Formed Tempered Martensitic Steel Sheet

“…steels [14][15][16][17][18] and tempered martensitic steels, 19,20) have been evaluated in previous studies using the above-mentioned techniques.…”

Performance of Mechanical Properties of Ultrahigh-Strength Ferrous Steels Related to Strain-Induced Transformation

“…One review and nine research articles have been published in this Special Issue of Metals. The subjects of this Issue are roughly divided into four categories: (1) strain-induced transformation behavior [1][2][3], (2) deformation mechanism [4,5], (3) formability [6,7] and (4) mechanical properties [8][9][10] of the ultrahigh-strength ferrous steels. The abovementioned (1) and (2) give important information for improving (3) and (4).…”

Studies on the Mechanical Properties of C45 Steel with Martensitic Structure after a High Tempering Process

“…In [8] steels with 12% CR, enhanced with Z phase, were tested to determine the dependence between corrosion and its resistance to creeping. In [9], the mechanical properties, that is, the stretching and elongation, of ferritic and martensitic steel were tested, depending on the different share of C, N and W. In another aspect [10], it was proposed to develop ultra-high-strength steels, intended for cold stamping in the automotive industry, by using special alloy additions. In [11] presents the results of tests on the strength of steel as a result of the repeated quenching-partitioning-tempering process and replacement of 1.5% (wt.…”