The present disclosure relates to a thick steel material that can be appropriately used as a line pipe, a sour-resistant material and, more particularly, to a high-strength steel material having excellent sulfide stress corrosion cracking resistance and excellent resistance against propagation of sulfide stress corrosion cracking, and a method of manufacturing the steel material.

Provided is a steel sheet and a method for manufacturing same, the steel sheet which can be used for automobile parts and the like, having excellent bending workability, and excellent balance of strength and ductility and of strength and hole expansibility.

A steel material for a vacuum tube according to an aspect of the present disclosure may include C: 0.1˜0.2%, Si: 0.05∞0.5%, Mn: 1.0∞1.6%, Ni: 0.5∞1.0%, Cr: 1.5∞4.0%, and the balance of Fe and unavoidable impurities in percentage by weight, and may have a complex structure of ferrite and pearlite as a microstructure.

Disclosed is a stainless steel for a fuel cell separator, more specifically, a stainless steel for a fuel cell separator having a low contact resistance. According to an embodiment of the stainless steel for a fuel cell separator disclosed herein, an arithmetic mean summit curvature Ssc of the surface defined according to the ISO 25178 standard is at least 6.0 μm.sup.−1, a root mean square surface slope Sdq is at least 23, and a contact resistance is at most 10 mΩ.Math.cm.sup.2.

Provided is a ferritic stainless steel in which cracking is unlikely to be caused in the vicinity of a weld zone by the stress due to expansion, contraction, and deformation due to the thermal effect of welding in the case of performing welding after deep drawing and which is excellent in corrosion resistance in the vicinity of the weld zone. The ferritic stainless steel has a composition containing C: 0.001% to 0.020%, Si: 0.01% to 0.30%, Mn: 0.01% to 0.50%, P: 0.04% or less, S: 0.01% or less, Cr: 18.0% to 24.0%, Ni: 0.01% to 0.40%, Mo: 0.30% to 3.0%, Al: 0.01% to 0.15%, Ti: 0.01% to 0.50%, Nb: 0.01% to 0.50%, V: 0.01% to 0.50%, Co: 0.01% to 6.00%, B: 0.0002% to 0.0050%, and N: 0.001% to 0.020% on a mass basis, the remainder being Fe and inevitable impurities. The composition satisfies 0.30%≤Ti+Nb+V≤0.60%.

This disclosure is related to high yield strength steel where mechanical properties, such as elongation, ultimate tensile strength and yield strength in a sheet are maintained or enhanced via thermal treatment optionally provided during a galvanization coating operation.

The disclosed martensitic stainless steel is defined in its composition is by specified ranges of weight percentages of C; Mn; Si; ≤Mn+Si; ≤S; 10,000×Mn×S; P; Cr, with [Cr−10.3−80*(C+N).sup.2]≤(Mn+Ni); Ni; Mo; Mo+2W; Cu; Ti; V; Zr; Al; O; Ta; Nb; (Nb+Ta)/(C+N); Nb; N; Co; Cu+Co; Cu+Co+Ni; B; rare earths+Y; Ca; the remainder being iron and impurities resulting from processing. Its microstructure includes at least 75% martensite, at most 20% ferrite and at most 0.5% carbides, the size of the ferrite grains being between 4 and 80 μm, preferably between 5 and 40 μm. Also disclosed is a method of manufacturing such steel.

A hot stamped article having excellent shock absorption having a predetermined chemical composition, having a microstructure containing prior austenite having an average grain size of 3 μm or less and further containing at least one of lower bainite, martensite, and tempered martensite in an area ratio of 90% or more, and having a grain boundary solid solution ratio Z defined by Z=(mass % of one or both of Nb and Mo at grain boundaries)/(mass % of one or both of Nb and Mo at time of melting) of 0.3 or more.

A precipitation hardenable, martensitic stainless steel is disclosed. The alloy has the following broad composition in weight percent. TABLE-US-00001 Ni 10.5-12.5 Co 1.0-6.0 Mo 1.0-4.0 Ti 1.5-2.0 Cr  8.5-11.5 Al Up to 0.5 Mn  1.0 max. Si 0.75 max. B 0.01 max.
The balance of the alloy is iron and the usual impurities found in commercial grades of precipitation hardenable martensitic stainless steels as known to those skilled in the state of the art in melting practice for such steels. A method of making parts from the alloy and an article of manufacture made from the alloy are also described.

The present invention discloses to a Hot-work die steel electroslag remelted ingot and a manufacture method thereof. The electroslag remelted ingot comprises the following chemical components, C: 0.36-0.41%, Si: 0.80-1.10%, Mn: 1.00-3.00%, Cr: 4.90-5.40%, Mo: 1.35-1.55%, V: 0.4-0.7%, Ni≤0.04%, Cu≤0.04%%, S≤0.003%, P≤0.012%, O≤0.0015%, H≤0.0002%, N≤0.006%, 0.05%≤RE≤0.20%, the balance being Fe. The above percentage is percentage by mass. According to the present invention, the features of electroslag remelting under inert gas protection are fully combined and a rare earth alloy is precisely fed during the electroslag remelting, thus exerting the excellent effects of RE inclusion modification and micro-alloying under high purity and high uniformity conditions and realizing high-quality and high-performance Hot-work die steel.