First, what is the section size or material thickness of the 4130 steel?
Second, are you intending to heat treat the 4130 steel after it has been received or did you have the 4130 supplied as quenched and tempered and it did not pass impact testing at -42 deg C?
As metengr has indicated, it would make it a lot easier if you would tell us what you are trying to do.
What product are you dealing with?
What is the QTC size?
How are you heat treating? What kind of quench?
Yes, you can meet those mechanical properties with 4130, but you have to have a high percentage martensite formed on quenching, and you have to keep the sulfur and phosphorus low.
Products is API 6A Flanges, Destructive test has been carriedout to verify on th finished flanges and found that impact is low. Hardness and Tesile exactly meet the requirements.
Can we check impact on actual parts.what is the better way to achieve impact of 42J at -42 deg by heattreatment.
It's been a while since I have read 6A, but I think that if you take test specimens from the actual product (as opposed to from a QTC), they must come from 1/4 T of the thickest section of the product and the specimens from all tests (tensile, impact, and hardness) must come from actual product. In addition, if you have a failed test result, there are specific retest procedures you must follow to qualify the lot, you can't just ignore the test results and keep testing until you find results you like.
Get a copy of the standard and read up on the requirements, I am pretty sure it tells you exactly what needs to be done (probably re-heat treating the lot).
