Effect of chromium on the properties of high-strength steel 30N9K4MF

1. Additional alloying of steel 30N9K4MF with chromium (up to 3%) increases its resistance to tempering, the hardenability, and the quench hardness. 2. The optimal Cr addition is 1–2%, ensuring a good combination of strength and toughness after oil quenching and high-temperature tempering (550°): σb > 155 kgf/mm3, σ0.2 ≥ 130 kgf/mm3, δ5 > 15%, ω>55%,a1>7 kgf-m/cm2,a1−196=4–5 kgf-m/cm2,a0.25=3.5–4.5 kgf-m/cm2,ap=2–3 kgf-m/cm2, T50=−140 to −165°.