Yield Point and Temparature relationship of High Tensile Steel

Vashi

I have a steel material that has a yield strength of 515 mpa and a tensile strength of 615 mpa at zero degrees. What i need to know is will the tensile strength and yield strength be higher than 293 mpa at 80 degrees. The steel is ahigh tensile grade steel from china (Q390C).

FredGarvin

If it's Chinese, then I wouldn't count on any of those numbers.

Most common forms of steel are going to exhibit a general trend of decrease in yield strength and ultimate strength with increasing temperature. Since Q390C is not in any of my handy references, I can't comment exactly. However, if that alloy follows the same characteristics of regular alloy steels like a 4140, the yield point should be around 92-95% of the room temperature value according to MIL Handbook 5 (assuming your temperatures were in deg C).

Vashi

Thanks for your response. Yes I agree, it is difficult to count on these numbers. According to chinese standards. The Chemical Composition of these materials should be as follows. C-0.2,Si-0.55,Mn-1.00-1.6,P<0.045,S<0.035,V-0.02-0.2,NB-0.015-0.060,Ti-0.02-0.20,AL>0.015,CR<0.030,NI<0.7.

The yield Strength varies from 330 mpa to 390 mpa min allowed, with >50mm thick plates having the lowest min yield allowed at zero degrees.

Would this information help to determine if the mpa would be higher at 80 degrees c. And yes i was refering to the temprerature in C.

nucleus

The following is from Machinery’s Handbook for structural steel

Degrees Fahrenheit 210 400 570 750 930 1100 1300 1475
Strength % of 70 Deg F 103 132 122 86 49 28 ….. ……..