Abstract: A martensitic stainless steel is produced by continuously casting a melt comprising 0.0.04%-0.065% by weight C, about 0.25%-0.5% by weight Si, about 0.9%-1.2% by weight Mn, up to 0.025% P by weight, about 0.1%-0.16% by weight S, about 11.9%-12.8% by weight Cr, up to about 0.35% by weight Ni, about 0.5%-0.65% by weight Cu, about 0.03%-0.06% by weight N, about 0.02%-0.1% by weight V, and the balance being Fe with residual impurities, at a temperature between 2730° F. to 2820° F. and a specific casting speed to form a continuous strand of the alloy while not splitting or cracking. The strand is cut to length to form a slab which is descaled and hot worked during the subsequent hot working process where its thickness is reduced to form a plate of a specific gauge and width while not splitting or cracking at a segregation line through the slab and plate during hot working. Hot working of the continuously cast slab may be provided by either rolling or forging or a combination of both. The mold plate is air cooled.

Abstract: Provided is a steel alloy and process for manufacture thereof. The steel alloy has improved ductility, weldability and dimensional stability. Also provided is a manufacturing mold having a manifold that may be formed of the steel alloy. The manifold may include sprues or runners such that the manifold may be used in plastic injection mold. The steel alloy has the chemical composition comprised of (by weight percent) about 0.16-0.2 carbon, about 0.6-0.9 manganese, up to about 0.02 phosphorous, up to about 0.02 sulfur, about 0.25-0.45 silicon, about 2.3-2.7 chromium, up to about 0.2 nickel, up to about 0.15 copper, up to about 0.15 molybdenum, about 0.15-0.03 aluminum and the balance being iron with trace amounts of ordinarily present elements. The steel alloy is electric furnace melted, ladle refined, vacuum degassed and argon shield poured in order to ensure cleanliness and quality.

Abstract: A hot worked low alloy tool steel plate can be machined into mold base parts useful for holding tooling used in plastic injection molding. The tool steel alloy preferably exhibits desired strength, toughness, ductility, weldability, uniform hardness and dimensional stability. A process for manufacture of the steel plate includes hot working, hot roller leveling, air cooling and tempering to desired hardness.