Nip roll of a paper or board machine

1 - 8 . (canceled)

9 . A nip roll of a paper or board machine comprising a heatable roll manufactured of steel, having a thermal shock resistance greater than 6000 W/m 2 , a tensile strength greater than 1000 MPa, an elongation at fracture greater than 7%, a dynamic ductility greater than 20 J, and a surface hardness greater than 400 HV 20 .

10 . The roll of claim 9 wherein the material of the roll is quenched and tempered steel.

11 . The roll of claim 10 wherein the tempered steel is at a basic hardness of about 250 HV 20 .

12 . The roll of claim 10 wherein the tempered steel has a hardness in the quenched and tempered state which is greater than 400-500 HV 20 .

13 . The roll of claim 9 wherein the roll has a surface which is hard coated to increase wear resistance.

14 . The roll of claim 9 wherein the roll has a surface which is heat treated by induction hardening to increase wear resistance.

15 . The roll of claim 9 wherein the roll has a shell which is made of at least two different materials.

16 . The roll of claim 9 further comprising a long nip calender formed with the roll.

17 . A calender comprising:

a first calendering element selected from the group consisting of: a shoe roll, and a belt/roll;

a backing roll having at least a first layer forming a backing roll surface, the first layer having a thickness, and the roll surface forming a long nip of greater than 30 mm in length with the first calendering element;

a means for heating the backing roll surface to greater than 160° C.;

a web in heat transfer relation to the backing roll surface;

wherein the the first layer forming a backing roll surface is homogeneous in a direction defined by the thickness of the first layer and is formed of steel in a quenched and tempered state, so that the hardness of said surface is greater than 400 HV 20 , the first layer having a modulus of elasticity of greater than 200,000 MPa, a tensile strength of greater than 1,000 MPa, a bending fatigue strength greater than 350 MPa, a thermal conductivity of greater than 30 W/mK, an elongation at fracture of greater than 7% and a dynamic ductility greater than 20 J.

18 . The calender of claim 17 wherein the first layer is formed of martensite or bainite.

19 . The calender of claim 17 wherein the backing roll is formed of the first layer enveloping an inner part of the backing roll.

20 . The calender of claim 17 wherein the backing roll surface is coated with a wear resistant material, whereby the surface hardness is increased.

21 . A method of calendering a web comprising the steps of:

forming a backing roll having at least a first layer, the first layer forming a backing roll surface, the first layer having a thickness, and the roll surface forming a long nip of greater than 30 mm in length with a first calendering element, wherein the the first layer is homogeneous in a direction defined by the thickness of the first layer and is formed of steel in a quenched and tempered state, so that the hardness of the surface is greater than 400 HV 20 , the first layer having a modulus of elasticity of greater than 200,000 MPa, a tensile strength of greater than 1,000 MPa, a bending fatigue strength greater than 350 MPa, a thermal conductivity of greater than 30 W/mK, an elongation at fracture of greater than 7% and a dynamic ductility greater than 20 J;

heating the backing roll surface to greater than 160° C.; and

passing a web through the long nip to produce a thermal shock of greater than 6,000 W/m 2 in the first layer of the backing roll.

22 . The method of claim 21 wherein the backing roll is formed of the first layer enveloping an inner part of the backing roll.

23 . The method of claim 21 wherein the backing roll surface is coated with a wear resistant material, increasing the surface hardness.