Low carbon microalloyed steel

1. A low carbon microalloyed steel tube or bar, in a hot rolled and air cooled condition having a microstructure consisting precipitation strengthened ferrite and pearlite, said steel consisting essentially of in weight %: 0.06-0.30 C; 0.5-1.5 Mn; 0.04 max S; 0.025 max P; 1.0 max Si; >1.0-2.0 Ni; 0.05-0.30 V; 0.01-2.0 Cu; 0.0010-0.0250 N; up to 0.2 Cb; 0.05-0.3 Cr; up to 0.15 Mo; 0.01-0.03 Al; balance Fe and minor additions and impurities, and

wherein said steel has a carbon equivalent value, C.E., ranging between 0.3-0.55, calculated by the formula:

C

.

E

.

=

C

+

Mn

+

Si

6

+

Cu

+

Ni

15

+

Cr

+

Mo

+

V

+

Cb

5

⁢

.

2. The steel of claim 1 containing 0.25-2.0 Cu.

3. The steel of claim 1 containing >0.1-0.30 V.

4. The steel of claim 1 containing 0.06-0.15 C.

5. The steel of claim 1 in the form of a bar or tubular shape having a minimum yield strength of 45-80 ksi.

6. The steel of claim 5 having a minimum yield strength of 65 ksi.

7. A hot rolled and air cooled low carbon microalloyed steel in the form of a bar or tubular shape having a minimum yield strength of between 45-80 ksi and having a microstructure consisting of precipitation strengthened ferrite and pearlite, said steel consisting essentially of in weight %: 0.06-0.30 C; 0.5-1.5 Mn; 1.0 max Si; 0.04 max S; 0.025 max P; >1.0-2.0 Ni; >0.1-0.3 V; 0.01-2.0 Cu; 10-250 ppm N; up to 0.2 Cb; 0.05-0.3 Cr; up to 0.15 Mo; 0.01-0.03 Al; balance Fe and incidental additions and impurities; wherein said steel has a carbon equivalent value, C.E., of between about 0.3-0.55, derived from the following formula:

C

.

E

.

=

C

+

Mn

+

Si

6

+

Cu

+

Ni

15

+

Cr

+

Mo

+

V

+

Cb

5

⁢

.