One aspect of the present disclosure is directed to low-alloy steels exhibiting high hardness and an advantageous level of multi-hit ballistic resistance with minimal crack propagation imparting a level of ballistic performance suitable for military armor applications. Certain embodiments of the steels according to the present disclosure have hardness in excess of 550 HBN and demonstrate a high level of ballistic penetration resistance relative to conventional military specifications.

The present invention provides an integrally cast excavator bucket and a manufacturing method thereof. The integrally cast excavator bucket comprises a lifting lug, a top plate, two side plates and a bottom plate connected with the two side plates. A method for manufacturing the integrally cast excavator bucket by adopting the cast steel comprises the following steps: putting cast steel components into a melting furnace, and carrying out modification treatment before furnace after melting is finished; manufacturing models and a template, coating, heating, vacuumizing, placing sandboxes, adding sand, molding, carrying out mold closing, casting, quenching, tempering and cooling to room temperature to finish casting of the excavator bucket. The integrally cast excavator bucket is formed by once casting from a low-alloy steel material by adopting a vacuum sealing technology, and is high in product strength, resistant to wear and corrosion, high in impact resistance and long in service life.

The present invention provides an integrally cast excavator bucket and a manufacturing method thereof. The integrally cast excavator bucket comprises a lifting lug, a top plate, two side plates and a bottom plate connected with the two side plates. A method for manufacturing the integrally cast excavator bucket by adopting the cast steel comprises the following steps: putting cast steel components into a melting furnace, and carrying out modification treatment before furnace after melting is finished; manufacturing models and a template, coating, heating, vacuumizing, placing sandboxes, adding sand, molding, carrying out mold closing, casting, quenching, tempering and cooling to room temperature to finish casting of the excavator bucket. The integrally cast excavator bucket is formed by once casting from a low-alloy steel material by adopting a vacuum sealing technology, and is high in product strength, resistant to wear and corrosion, high in impact resistance and long in service life.

The invention relates to a creping blade for the detachment of a travelling paper web from a dryer cylinder, said blade having a working edge to be placed against the cylinder, wherein the creping blade has a tensile strength of 1800-2500 N/mm.sup.2 and a hardness of 57-66 HRC in the hardened and tempered condition and wherein the blade is made from a steel, which comprises the following main components (in wt. %): C: 1.2-1.5; Si: 0.1-0.8; Mn: 0.1-0.7; Cr: 4.2-5.2; Mo: 3.0-4.0; V: 3.2-4.2; N: 0.01-0.15; balance Fe and impurities.

The invention relates to a creping blade for the detachment of a travelling paper web from a dryer cylinder, said blade having a working edge to be placed against the cylinder, wherein the creping blade has a tensile strength of 1800-2500 N/mm.sup.2 and a hardness of 57-66 HRC in the hardened and tempered condition and wherein the blade is made from a steel, which comprises the following main components (in wt. %): C: 1.2-1.5; Si: 0.1-0.8; Mn: 0.1-0.7; Cr: 4.2-5.2; Mo: 3.0-4.0; V: 3.2-4.2; N: 0.01-0.15; balance Fe and impurities.

Disclosed are: a cold forging wire rod and a steel part in which the microstructure is controlled through the alloy composition and manufacturing method, thus enabling cost reduction and enhancing delayed fracture resistance; and a method for manufacturing same. The steel part having improved delayed fracture resistance according to an embodiment of the present invention contains, in weight percent, 0.18-0.25% of C, 0.30-0.50% of Si, 0.35-0.50% of Mn, more than 0% and no more than 0.03% of P, more than 0% and no more than 0.03% of S, 0.45-0.60% of Cr, 0.015-0.03% of Ti, 0.001-0.004% of B, with the remainder comprising Fe and inevitable impurities, and may include at least 90% by volume of auto-tempered martensite.

Disclosed are: a cold forging wire rod and a steel part in which the microstructure is controlled through the alloy composition and manufacturing method, thus enabling cost reduction and enhancing delayed fracture resistance; and a method for manufacturing same. The steel part having improved delayed fracture resistance according to an embodiment of the present invention contains, in weight percent, 0.18-0.25% of C, 0.30-0.50% of Si, 0.35-0.50% of Mn, more than 0% and no more than 0.03% of P, more than 0% and no more than 0.03% of S, 0.45-0.60% of Cr, 0.015-0.03% of Ti, 0.001-0.004% of B, with the remainder comprising Fe and inevitable impurities, and may include at least 90% by volume of auto-tempered martensite.

A process for quenching heat treated metal parts using a liquid quenchant and high pressure is disclosed. In general, the process includes the steps of providing a load of heat treated metal parts in a pressure vessel wherein the load is at an elevated temperature after being heat treated. In a subsequent step, a liquid quenchant is injected into the pressure vessel such that a vapor of the liquid quenchant forms rapidly in the pressure vessel and cools the metal parts. The step of injecting the liquid quenchant into the pressure vessel is continued for a time sufficient to establish a desired peak vapor pressure in the pressure vessel. An apparatus for carrying out the disclosed process is also described.

A cooling apparatus includes: cooling nozzles which are disposed around an object to be treated accommodated inside a cooling room and spray a cooling medium onto the object to be treated; a header pipe communicating with the cooling nozzles; and a cooling pump which supplies the cooling medium to the header pipe. The cooling nozzles are divided into groups. The header pipe is provided in each of the groups of the cooling nozzles.

A cooling apparatus includes: cooling nozzles which are disposed around an object to be treated accommodated inside a cooling room and spray a cooling medium onto the object to be treated; a header pipe communicating with the cooling nozzles; and a cooling pump which supplies the cooling medium to the header pipe. The cooling nozzles are divided into groups. The header pipe is provided in each of the groups of the cooling nozzles.