selection of proper steel bar for ASTM A320 L7M bolting

[sam1212]

Daer Experts,

I have to produce bolting (different diameters 14mm-68mm) as per ASTM A320 grade L7M. Before I did not work with ASTM specs, and I have some doubts with proper selection of steel bar for bolting manufacturing. Please help me with my questions, listed below:

1) I got the following offer from steel manufacturer: “AISI 4140 round bars, cold drawn, peeled with max hardness 310HB”.
But ASTM A320 spec says "... the term bolting material as used in this spec covers bars, bolts, screws, studs, stud bolts and wire. Bar and wire shall be hot wrought. The material may be further processed by centerless grinding or by cold drawing."
Does it mean that offered cold drawn 4140 bars are not suitable for producing bolting as per ASTM A320?

2) ASTM A320 spec specifies hardness in range 200 HB-max 235HB for grade L7M.
Can I still have above mentioned 4140 bar with max hardness 320HB and heat treat them to 200-235HB to satisfy to L7M grade requirements?

 

[metengr]

The 4140 cold drawn bar material is acceptable, but you must have MTR's for the purchased material to ensure compliance with chemical composition requirements in Table 4 of A 320. The bar material must be reheat treated in accordance with Table 1 of A 320 to ensure mechanical properties and impact values in accordance with Table 3 of A 320 are met. Please review A 320 material specification before certification as ASTM A 320 bolting.

 

[sam1212]

Thanks a lot metengr