Flow meter with rotor assembly

1. A flow meter for determining a flow rate of a fluid, comprising:

a housing comprising a flow bore;

a rotor assembly rotatable by the flow of fluid within the flow bore and comprising a thermally diffused metallic material, wherein the thermally diffused metallic material comprises a metallic material and a diffusion substance; and

a sensor unit configured to generate a signal indicative of a rotational rate of the rotor assembly.

2. The flow meter of claim 1 , wherein the rotor assembly comprises a rotor shaft comprising the thermally diffused metallic material.

3. The flow meter of claim 2 , wherein the rotor assembly comprises a rotor shaft and a rotor comprising rotor blades, the rotor being at least partially located in the flow bore.

4. The flow meter of claim 3 , wherein the rotor blades comprise turbine blades.

5. The flow meter of claim 3 , wherein the rotor is fixedly coupled to the rotor shaft by machine pressing.

6. The flow meter of claim 1 , wherein the rotor assembly comprises a rotor shaft and rotor blades integral with the rotor shaft, the rotor blades being at least partially located in the flow bore.

7. The flow meter of claim 6 , wherein the integral rotor blades comprise turbine blades.

8. The flow meter of claim 6 , wherein the rotor shaft and the integral rotor blades are formed by additive manufacturing.

9. The flow meter of claim 1 , wherein the thermally diffused metallic material comprises a hardened surface, hardened by changing a molecular structure of the surface through thermal chemical diffusion of the diffusion substance.

10. The flow meter of claim 1 , wherein the thermally diffused metallic material comprises a steel alloy.

11. The flow meter of claim 1 , wherein the thermally diffused metallic material is configured to resist erosion, corrosion, and cracking.

12. The flow meter of claim 1 , wherein the fluid comprises a hydrocarbon fluid.

13. A rotor assembly for rotating in a flow bore in a flow meter housing, the assembly comprising a rotor shaft comprising a thermally diffused metallic material and rotatable by the flow of fluid in the flow meter housing, wherein the thermally diffused metallic material comprises a metallic material and a diffusion substance.

14. The rotor assembly of claim 13 , further comprising a rotor comprising rotor blades.

15. The rotor assembly of claim 14 , wherein the rotor blades are integral with the rotor shaft.

16. The rotor assembly of claim 15 , wherein the rotor shaft and the integral rotor blades are formed by additive manufacturing.

17. A method for determining a flow rate of a fluid, comprising:

flowing a fluid through a flow bore of a housing;

rotating a rotor assembly with the fluid flowing through the flow bore, wherein the rotor assembly comprises a thermally diffused metallic material, wherein the thermally diffused metallic material comprises a metallic material and a diffusion substance;

detecting a rotational rate of the rotating rotor;

generating a signal indicative of the rotational rate of the rotor; and

determining the flow rate of the fluid using the signal.

18. The method of claim 17 , wherein the rotating comprises rotating a shaft comprising the thermally diffused metallic material.

19. The method of claim 17 , wherein the rotating comprises rotating a shaft and rotor blades integral with the rotor shaft, the rotor blades being at least partially in the flow bore.

20. The flow meter of claim 1 , wherein the thermally diffused metallic material has a hardness of about 10 to about 40, on the Rockwell C scale, greater than the hardness of the metallic material.

21. The rotor assembly of claim 13 , wherein the thermally diffused metallic material has a hardness of about 10 to about 40, on the Rockwell C scale, greater than the hardness of the metallic material.

22. The method of claim 17 , wherein the thermally diffused metallic material has a hardness of about 10 to about 40, on the Rockwell C scale, greater than the hardness of the metallic material.