There is provided a centrifugally cast composite roll for rolling having excellent wear resistance and surface deterioration resistance at levels of a high-speed steel cast iron roll and having rolling incident resistance at a level of a high alloy grain cast iron roll. A centrifugally cast composite roll for rolling having an outer layer and an inner layer, the outer layer including chemical components by mass ratio: C: 1.0 to 3.0%; Si: 0.3 to 3.0%; Mn: 0.1 to 3.0%; Ni: 0.1 to 6.0%; Cr: 0.5 to 6.0%; Mo: 0.5 to 6.0%; V: 3.0 to 7.0%; Nb: 0.1 to 3.0%; B: 0.001 to 0.1%; N: 0.005 to 0.070%; and the balance being Fe and inevitable impurities, wherein: the chemical composition of the outer layer satisfies following Formula (1), has a crystallization and precipitation amount of graphite suppressed to less than 0.3% by area ratio, and has 1 to 15% of MC carbide by area ratio; and the centrifugally cast composite roll for rolling does not have a cast defect having a diameter of ϕ4 mm or more at a boundary between the outer layer and the inner layer,

50×N+V<9.0  (1).

There is provided a centrifugally cast composite roll for rolling having excellent wear resistance and surface deterioration resistance at levels of a high-speed steel cast iron roll and having rolling incident resistance at a level of a high alloy grain cast iron roll. Its outer layer includes chemical components by mass ratio: C: 1.5 to 3.5%; Si: 0.3 to 3.0%; Mn: 0.1 to 3.0%; Ni: 1.0 to 6.0%; Cr: 1.5 to 6.0%; Mo: 0.1 to 2.5%; V: 2.0 to 6.0%; Nb: 0.1 to 3.0%; B: 0.001 to 0.2%; N: 0.005 to 0.070%; and the balance being Fe and inevitable impurities, wherein: a chemical composition of the outer layer satisfies Formula (1) and has 5 to 30% of M.sub.3C carbide by area ratio; an outer layer Shore hardness (A) of a roll surface satisfies Formula (2); and a residual stress (B) of the roll surface satisfies Formula (3),

2×Ni+0.5×Cr+Mo>10.0  (1)

Hs 75≤A≤Hs 85  (2)

100 MPa≤B≤350 MPa  (3).

There is provided a centrifugally cast composite roll for rolling having excellent wear resistance and surface deterioration resistance at levels of a high-speed steel cast iron roll and having rolling incident resistance at a level of a high alloy grain cast iron roll. Its outer layer includes chemical components by mass ratio: C: 1.5 to 3.5%; Si: 0.3 to 3.0%; Mn: 0.1 to 3.0%; Ni: 1.0 to 6.0%; Cr: 1.5 to 6.0%; Mo: 0.1 to 2.5%; V: 2.0 to 6.0%; Nb: 0.1 to 3.0%; B: 0.001 to 0.2%; N: 0.005 to 0.070%; and the balance being Fe and inevitable impurities, wherein: a chemical composition of the outer layer satisfies Formula (1) and has 5 to 30% of M.sub.3C carbide by area ratio; an outer layer Shore hardness (A) of a roll surface satisfies Formula (2); and a residual stress (B) of the roll surface satisfies Formula (3),

2×Ni+0.5×Cr+Mo>10.0  (1)

Hs 75≤A≤Hs 85  (2)

100 MPa≤B≤350 MPa  (3).

A machine component, made of steel or cast iron and having a circular hole that opens in a first surface, includes a plurality of first quench-hardened regions that include the first surface and are arranged apart from each other along a first circle surrounding the hole when viewed in a plane in a direction perpendicular to the first surface, and a base region that is a region other than the first quench-hardened regions.

A machine component, made of steel or cast iron and having a circular hole that opens in a first surface, includes a plurality of first quench-hardened regions that include the first surface and are arranged apart from each other along a first circle surrounding the hole when viewed in a plane in a direction perpendicular to the first surface, and a base region that is a region other than the first quench-hardened regions.

A method is disclosed for producing a brake element, in particular a brake disk or brake drum, which has a friction portion and a fastening portion, wherein a blank for at least the friction portion is produced by a casting method from gray cast iron with lamellar graphite, wherein the blank is subjected to austenitizing at a predefined austenitizing temperature, and wherein the austenitized blank is subjected to austempering at a predefined austempering temperature. The friction portion and the fastening portion is produced in one piece, and that the fastening portion is produced with a wall thickness of at least 1.5 and at most 4.5 mm.

A method is disclosed for producing a brake element, in particular a brake disk or brake drum, which has a friction portion and a fastening portion, wherein a blank for at least the friction portion is produced by a casting method from gray cast iron with lamellar graphite, wherein the blank is subjected to austenitizing at a predefined austenitizing temperature, and wherein the austenitized blank is subjected to austempering at a predefined austempering temperature. The friction portion and the fastening portion is produced in one piece, and that the fastening portion is produced with a wall thickness of at least 1.5 and at most 4.5 mm.

The present invention suppresses leakage of combustion gas from a contact surface. A cylinder head (20) is attached to a cylinder block. The surface (26) of the side of the cylinder head (20) that is attached to the cylinder block includes a first region (AH1) and a second region (AH2) that has higher hardness than the first region (AH1).

The present invention suppresses leakage of combustion gas from a contact surface. A cylinder head (20) is attached to a cylinder block. The surface (26) of the side of the cylinder head (20) that is attached to the cylinder block includes a first region (AH1) and a second region (AH2) that has higher hardness than the first region (AH1).

Cast alloys comprising 20 to 35 wt. % nickel; 25% to 42.5 wt. % chromium; 1.5 to 2.5 wt. % carbon; 0.5 to 2.0 wt. % manganese; 0.25 to 2.0 wt. % silicon; 0 to 1.5 wt. % aluminum; 0 to 0.5 wt. % titanium, niobium, tantalum combined, 0 to 1 wt. % copper, other residual elements up to 0.5 wt. %, and iron to bring the total percentage to 100 wt. %, are described. The cast alloys can be used to form components for mixers, turbines and pumps, such as impellers, diffusers, and spacers, or for fracking operations as seats or flow diverters, as well as other oil and gas or energy industry components. In some applications, the cast alloys are custom made for downhole electro submersible pump applications.