Experimental study on the effect of boron on hydrogen embrittlement fracture of low-carbon thin wear-resistant plates
Martensitic low-carbon thin wear-resistant plates are used to manufacture automotive parts that must have ultra-high strength and be able to withstand side impacts and rollovers. This wear-resistant plate is usually used to make shaped parts through roll forming. Recently steel parts with martensitic microstructures and more complex shapes have been successfully produced by hot stamping and then press quenching at austenite stabilizing temperatures.
A systematic study on the effect of tempering on tensile specimens of AISI10B22, 0.22wt%C, 22MnB5 boron alloy thin wear-resistant plates found that after 6%-8% of the specimens were tempered to martensite at 150-350oC, the strength was 1200MPa There is almost no change in the ductility of the wear-resistant plate between 1600MPa and 1600MPa. After increasing the tempering temperature, a large amount of discontinuous yielding occurs, strain hardening is reduced, and the strength is reduced. Wear-resistant plates with a carbon content of 0.4wt%, quenched, and tempered to super-strength steel, especially medium-carbon steel, are highly sensitive to hydrogen embrittlement. When plating high-strength fasteners with chromium or cadmium, hydrogen is introduced by electroplating, and the sensitivity to hydrogen embrittlement must be reduced through low-temperature baking at around 150oC. The main characteristics of hydrogen embrittlement of medium carbon steel are intergranular fractures at the original austenite grain boundaries, and the precipitation of phosphorus, antimony, tin, and arsenic atoms.
The hydrogen embrittlement of iron and low carbon wear-resistant plates manifests itself as transgranular fracture and intergranular fracture. The brittle intergranular fracture occurs on the slip plane instead of the {100} cleavage plane of the body-centered cubic structure, which is consistent with the slip plane debonding mechanism. Mild steel is commonly welded and suffers from hydrogen embrittlement damage.
