Method of producing a steel moulding

Abstract

The invention relates to a method of producing a steel moulding using a sinter powder with a base of iron containing at least one non-ferrous metal selected from a group comprising Mn, Cr, Si, Mo, Co, V, B, Be, Ni and Al, the rest being Fe and unavoidable impurities resulting from the manufacturing process, comprising the steps of preparing the sinter powder, compacting the sinter powder to produce a green compact in a mould, sintering the green compact under a reducing atmosphere and then cooling and hardening, characterised in that the total proportion of non-ferrous metals in the sinter powder is selected from a range with a lower limit of 1% by weight and an upper limit of 60% by weight, and the sinter powder is sintered to an at least approximately completely austenitic structure, and hardening takes place by subjecting the steel moulding to mechanical load so that the austenitic structure is transformed at least partially to a martensitic structure.

1 . Method of producing a steel moulding using a sinter powder with a base of iron containing at least one non-ferrous metal selected from a group comprising Mn, Cr, Si, Mo, Co, V, B, Be, Ni and Al, the rest being Fe and unavoidable impurities resulting from the manufacturing process, comprising the steps of preparing the sinter powder, compacting the sinter powder to produce a green compact in a mould, sintering the green compact under a reducing atmosphere and then cooling and hardening, wherein the total proportion of non-ferrous metals in the sinter powder is selected from a range with a lower limit of 1% by weight and an upper limit of 60% by weight, and the sinter powder is sintered to an at least approximately completely austenitic structure, and hardening takes place by subjecting the steel moulding to mechanical load so that the austenitic structure is transformed at least partially to a martensitic structure. 
     
     
         2 . Method as claimed in  claim 1 , wherein the mechanical-load is obtained by applying a pressure which is at least as high as the pressure at −10% of the pressure threshold of the respective material (measured in accordance with DIN 50106). 
     
     
         3 . Method as claimed in  claim 1 , wherein the mechanical load is produced at a temperature selected from a range with a lower limit of 20° C. and an upper limit of 180° C. or selected from a range with a lower limit of 180° C. and an upper limit of 550° C. 
     
     
         4 . Method as, claimed in  claim 1 , wherein a carburizing gas is added to the reducing atmosphere for the sintering process or a carburizing gas is used as the reducing atmosphere. 
     
     
         5 . Method as claimed in  claim 1 , wherein the steel moulding is produced with a core density of 7.3 g/cm 3  maximum. 
     
     
         6 . Method as claimed in  claim 1 , wherein graphite is added to the sinter powder in a proportion selected from a range with a lower limit of 0.1% by weight and an upper limit of 5% by weight. 
     
     
         7 . Method as claimed in  claim 1 , wherein up to 8% by weight of pressing agent and/or up to 2% by weight of binding agent, in particular an organic one, is added to the iron-based powder. 
     
     
         8 . Method as claimed in  claim 1 , wherein an additional sinter powder is placed in the mould and compacted together with the iron-based sinter powder 
     
     
         9 . Method as claimed in  claim 1 , wherein a semi-finished moulding is produced in a first step and placed in the mould, and at least certain regions of it are coated with the steel powder with an iron base and sintered jointly with the steel powder with an iron base. 
     
     
         10 . Method as claimed in  claim 1 , wherein a semi-finished moulding is produced from the sinter powder with an iron base in a first step and the semi-finished moulding is joined to another semi-finished moulding made from a sinter powder that is different from the sinter powder of the first semi-finished moulding in another step. 
     
     
         11 . Sintered moulding with a moulding body made from a sinter powder with an iron base containing at least one non-ferrous metal selected from a group comprising Mn, Cr, Si, Mo, Co, V, B, Be, Ni and Al, the rest being Fe with unavoidable impurities caused by the production process, wherein the total proportion of the at least one non-ferrous metal in the sinter powder is selected from a range with a lower limit of 1% by weight and an upper limit of 60% by weight and the moulding body has a martensitic structure at least at the surface or in regions close to the surface or in surface regions induced by a reaction under high mechanical load. 
     
     
         12 . Sintered component as claimed in  claim 11 , wherein part of the moulding body is produced from another sinter powder that is different from the sinter powder with an iron base.