Component made of b-zr alloyed steel

Abstract

Component with a steel part, wherein the steel, among other things, 0.30-0.50 wt. % C, 0.05-1.3 wt. % Mn, 0.001-0.015 wt. % P, 0.001-0.015 wt. % S, 0.01-0.8 wt. % Si, 0.3-1.5 wt. % Cr, 0.005-0.40 wt. % V, 0.0008-0.0050 wt. % B, 0.02-0.35 wt. % Al, 0.0001-0.0200 wt. % N, 0.01-0.08 wt. % Ti, and 0.0030-0.0800 wt. % Zr; comprises the rest iron and unavoidable impurities, wherein the B content in the steel at a depth of 5-60 μm is ≥80% of the B content in the steel at a depth of 500 μm.

1 . A component with a steel part, the component comprising: steel having
 0.30-0.50 wt. % C,   0.05-1.3 wt. % Mn,   0.001-0.015 wt. % P,   0.001-0.015 wt. % S,   0.01-0.8 wt. % Si,   0.3-1.5 wt. % Cr,   0.005-0.40 wt. % V,   0.0008-0.0050 wt. % B,   0.02-0.35 wt. % Al,   0.0001-0.0200 wt. % N,   0.01-0.08 wt. % Ti, and   0.0030-0.0800 wt. % Zr;   wherein the part of the component has a steel surface and the B content in the steel at a depth of 5-60 μm is ≥80% of the B content in the steel at a depth of 500 μm, the depth being measured perpendicular to the steel surface.   
     
     
         2 . The component of  claim 1 , wherein the B content in the steel at a depth of 5-60 μm is ≥90% of the B content in the steel at a depth of 500 μm. 
     
     
         3 . The component of  claim 1 , wherein the B content in the steel at a depth of 140-220 μm is ≥80% of the B content in the steel at a depth of 500 μm, the depth being measured perpendicular to the steel surface. 
     
     
         4 . The component of  claim 1 , wherein the B content in the steel at a depth of 140-220 μm is ≥90% of the B content of the steel at a depth of 500 μm. 
     
     
         5 . The component of  claim 1 , wherein the steel consists of unavoidable impurity that amounts to ≤0.01 wt. %. 
     
     
         6 . The component of  claim 1 , wherein the steel comprises:
 0.30-0.46 wt. % C,   0.01-0.60 wt. % Si,   0.3-1.3 wt. % Cr,   0.005-0.35 wt. % V,   0.0012-0.0050 wt. % B,   0.02-0.25 wt. % Al,   0.0020-0.0150 wt. % N,   0.014-0.060 wt. % Ti, and   0.0050-0.0500 wt. % Zr.   
     
     
         7 . The component of  claim 1 , wherein the steel comprises:
 0.01-0.20 wt. % Mo,   0.01-0.50 wt. % Ni,   0.01-0.50 wt. % Cu,   0.0010-0.0100 wt. % Ca,   0.01-0.10 wt. % Bi,   0.01-0.30 wt. % Co,   0.01-0.06 wt. % Nb,   0.01-0.40 wt. % Pb,   0.01-0.10 wt. % Se,   0.01-0.10 wt. % Te,   0.01-0.3 wt. % W,   0.01-0.04 wt. % As,   0.01-0.02 wt. % Sn,   0.01-0.20 wt. % Ta,   0.01-0.20 wt. % Ce,   0.01-0.50 wt. % Sn,   0.01-0.40 wt. % Sb,   0.01-0.20 wt. % Hf, and/or   one or more lanthanoid(s), each in an amount of 0.01-0.02 wt. %.   
     
     
         8 . The component of  claim 1 , wherein (Zr+Ti+Al)/N is in a range from 2.7 to 150. 
     
     
         9 . The component of  claim 1 , wherein the steel part has a Vickers hardness at a depth of 30-100 μm, preferably 40-120 μm measured from the surface perpendicular to the surface of the steel part, which is less than 150 HV 0.3 below the Vickers hardness HV 0.3 of the steel part at a depth of 400 μm. 
     
     
         10 . The component of  claim 1 , wherein the component is a fastening means selected from the group consisting of screws, nuts, rivets, bolts and chains. 
     
     
         11 . The component of  claim 1 , wherein the steel makes up at least 90 wt. % of the component and/or the component has a tensile strength according to ISO 898-1:2021 of ≥800 MPa. 
     
     
         12 . The component of  claim 1 , wherein the microstructure of the steel is bainitic and/or martensitic after tempering ≥90% by volume. 
     
     
         13 . The component of  claim 1 , wherein the microstructure of the steel without tempering is ≥90% by volume ferritic-pearlitic. 
     
     
         14 . A method of manufacturing a component with a steel part, the method comprising the steps of:
 Providing a steel with a composition having 0.30-0.50 wt. % C, 0.05-1.3 wt. % Mn, 0.001-0.015 wt. % P, 0.001-0.015 wt. % S, 0.01-0.8 wt. % Si, 0.3-1.5 wt. % Cr, 0.005-0.40 wt. % V, 0.0008-0.0050 wt. % B, 0.02-0.35 wt. % Al, 0.0001-0.0200 wt. % N, 0.01-0.08 wt. % Ti, and 0.0030-0.0800 wt. % Zr; and   Forming at least a part of a component with the steel.   
     
     
         15 . The method of  claim 14 , further comprising the steps of:
 a) thermomechanical rolling of the steel,   b) production of a wire or bar of steel, and   c) wire drawing.   
     
     
         16 . The method of  claim 14 , further comprising the step of heat treatment and/or tempering the steel. 
     
     
         17 . The method of  claim 14 , further comprising the step of heating to 700-750° C. for 6-10 hours.