Ascometal

Ascometal (societe Anonyme)

Claude Pichard

Jacques Bellus

Pierre Jolly

Daniel Robat

Daniel Forest

Vincent Jacot

Christian Tomme

Gilles Pierson

Process for manufacturing a mechanical component made of steel, in which a blank of the steel component is manufactured and a high-temperature carburizing or carbonitriding treatment of at least part of the surface of the blank of the component is carried out, the chemical composition of the steel of which the component is composed comprises, by weight: 0.15%.ltoreq.C.ltoreq.0.35%; 0%.ltoreq.Si.ltoreq.0.6%; 0%.ltoreq.Mn+Cr+Ni+Mo.ltoreq.5%; 0%.ltoreq.Al.ltoreq.0.1%; 0%.ltoreq.Cu.ltoreq.0.5%; 0%.ltoreq.Ti.ltoreq.0.05%; 0.004%.ltoreq.N.ltoreq.0.02%; 0%.ltoreq.S.ltoreq.0.15%; P.ltoreq.0.03%; optionally, up to 0.02% tellurium, up to 0.04% selenium, up to 0.07% lead, up to 0.005% calcium, the balance being iron and impurities resulting from the smelting; the chemical composition being adjusted so that the Jominy curve of the steel is such that: 45 HRC.ltoreq.J.sub.3 .ltoreq.50 HRC; 39 HRC.ltoreq.J.sub.11 .ltoreq.47 HRC; 31 HRC.ltoreq.J.sub.25 .ltoreq.40 HRC; the average values J.sub.3m, J.sub.11m and J.sub.25m of five Jominy tests are such that: .vertline.J.sub.11m -J.sub.3m .times.14/22-J.sub.25m .times.8/22.vertline..ltoreq.2.5 HRC and J.sub.3m -J.sub.15m .ltoreq.9 HRC. Carburizing or carbonitriding steel for manufacturing this component.

Process for manufacturing a carburized or carbonitrided steel component,

The invention relates to a steel and to a process for the manufacture of a steel component formed by cold plastic deformation.

Steel and process for the manufacture of a steel component formed by

Steel chemical composition of which contains, by weight: 0.1%.ltoreq.C.ltoreq.0.4%; 1%.ltoreq.Mn.ltoreq.1.8%; 0.15%.ltoreq.Si.ltoreq.1.7%; 0%.ltoreq.Ni.ltoreq.1%; 0%.ltoreq.Cr.ltoreq.1.2%; 0%.ltoreq.Mo.ltoreq.0.3%; 0%.ltoreq.V.ltoreq.0.3%; Cu.ltoreq.0.35%; optionally from 0.005% to 0.06% of aluminum, optionally boron in contents of between 0.0005% and 0.01%, optionally between 0.005% and 0.03% of titanium, optionally between 0.005% and 0.06% of niobium, optionally from 0.005% to 0.1% of sulfur, optionally up to 0.007% of calcium, optionally up to 0.03% of tellurium, optionally up to 0.05% of selenium, optionally up to 0.05% of bismuth, optionally up to 0.1% of lead, the balance being iron and impurities resulting from smelting. Process for the manufacture of a forging.

Process for manufacturing a forging

Steel for the manufacture of forgings having a bainitic structure and the mechanical properties of which are: R.sub.p0.2 .gtoreq.800 MPa, R.sub.m .gtoreq.1000 MPa, K.sub.cu .gtoreq.50 J/cm.sup.2 its chemical composition comprising, by weight: 0.05%.ltoreq.C.ltoreq.0.12%, 0.1%.ltoreq.Si.ltoreq.0.45%, 1.01%.ltoreq.Mn.ltoreq.1.8%, 0.15%.ltoreq.Cr .ltoreq.1.15%, 0.06%.ltoreq.Mo.ltoreq.0.12%, Cu.ltoreq.0.30%, Ni.ltoreq.0.30%, 0.01%.ltoreq.Ti.ltoreq.0.04%, 0.005%.ltoreq.Al.ltoreq.0.04%, 0.006%.ltoreq.N.ltoreq.0.013%, 0.0005% 5 B.ltoreq.0.004%, P.ltoreq.0.025%, 0.02%.ltoreq.S.ltoreq.0.1%, 0%.ltoreq.Pb.ltoreq.0.1%, 0%.ltoreq.Te.ltoreq.0.07%, optionally from 0.0002% to 0.002% of calcium, the balance being iron and impurities resulting from the smelting, the chemical composition furthermore satisfying the relationship: 0.2% .ltoreq.Ni+Mo+Cu.ltoreq.0.7%, the uncombined boron content not being less than 0.0005% above 950.degree. C. Process for the manufacture of a forging.

Steel for the manufacture of forging having a bainitic structure and

The invention relates to a method for fabricating a piece of structural steel that includes thermal or thermomechanical treatment steps that could ordinarily lower the fatigue strength and shock and impact resistance of the steel piece. In the method of the invention a workpiece of microalloy steel is fabricated containing the following elements in the mounts indicated and having a bainitic structure:

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Malancourt la Montagne, France

Claude Pichard