Additive manufacturing of ferritic/martensitic steel with improved high temperature strength
Techniques for using additive manufacturing (AM) to fabricate creep resistant ferritic/martensitic steel with improved high temperature strength are described. AM processing may be performed on Grade 91 steel powder. Beam powers from about 221 W to about 270 W may be used. Traverse rates from about 675 mm/s to about 825 mm/s may be used. Heat inputs ranging from about 55.7 J/mm 3 to about 83.2 J/mm 3 may be produced. Creep resistant ferritic/martensitic steel, produced according to the present disclosure, has improved strain yield strength and ductility as compared to wrought steel.
1. A creep resistant ferritic and martensitic steel produced from powder bed fusion (PBF) additive manufacturing (AM) of steel powder, comprising:
improved ductility as compared to a wrought steel;
wherein the creep resistant ferritic and martensitic steel is produced from PBF AM of Grade 91 steel powder; and
wherein when the creep resistant ferritic and martensitic steel is annealed for about 20 hours at 600° C., the annealed creep resistant ferritic and martensitic steel has a strain yield strength of 870 MPa at room temperature.
2. The creep resistant ferritic and martensitic steel of claim 1 , wherein the creep resistant ferritic and martensitic steel has a strain yield strength of 700 MPa at 600° C.
3. The creep resistant ferritic and martensitic steel of claim 1 , wherein the creep resistant ferritic and martensitic steel has a ductility of 0.09 at room temperature.
4. The creep resistant ferritic and martensitic steel of claim 1 , wherein the creep resistant ferritic and martensitic steel has a ductility of 0.05 at 600° C.
5. The creep resistant ferritic and martensitic steel of claim 1 , wherein:
the annealed creep resistant ferritic and martensitic steel has a ductility of 0.08 at room temperature.
6. The creep resistant ferritic and martensitic steel of claim 1 , wherein:
the annealed creep resistant ferritic and martensitic steel has a ductility of 0.03 at 600° C.
7. A creep resistant ferritic and martensitic steel produced from powder bed fusion (PBF) additive manufacturing (AM) of steel powder, comprising:
improved ductility as compared to a wrought steel;
wherein the creep resistant ferritic and martensitic steel is produced from PBF AM of Grade 91 steel powder; and
wherein when the creep resistant ferritic and martensitic steel is annealed for about 20 hours at 600° C., the annealed creep resistant ferritic and martensitic steel has a strain yield strength of 680 MPa at room temperature.
8. A creep resistant ferritic and martensitic steel produced from powder bed fusion (PBF) additive manufacturing (AM) of steel powder, comprising:
improved ductility as compared to a wrought steel;
wherein the creep resistant ferritic and martensitic steel is produced from PBF AM of Grade 91 steel powder; and
wherein when the creep resistant ferritic and martensitic steel is annealed for about 20 hours at 600° C., the annealed creep resistant ferritic and martensitic steel has a strain yield strength of 835 MPa at room temperature.
9. A method of producing the creep resistant ferritic and martensitic steel according to claim 1 , the method comprising:
obtaining a Grade 91 steel powder; and
performing a powder bed fusion (PBF) additive manufacturing (AM) using the Grade 91 steel powder.
10. The method of claim 9 , wherein the performing comprises using a beam power between about 221 W and about 270 W.
11. The method of claim 9 , wherein the performing comprises using a traverse rate between about 675 mm/s and about 825 mm/s.
12. The method of claim 9 , wherein the performing comprises producing a heat input between about 55.7 J/mm 3 and about 83.2 J/mm 3 .
13. The method of claim 9 , wherein the performing comprises a heat input value of about 68.1 J/mm 3 .
14. The method of claim 9 , wherein the performing comprises rotating a direction of deposition.
15. The method of claim 14 , wherein directions of deposition of adjacent layers of the steel powder are rotated about 67°.