AISI 4130 - Tangent modulus AISI 4130 - Tangent modulus sumacon2003 (Structural) (OP) 4 Feb 18 11:29 What is a reasonable value of tangent modulus for AISI 4130 material? ( 1Cr 0.5Mo Temperature 350 F ) SUMATECH, INC. www.sumacon.com RE: AISI 4130 - Tangent modulus sdm919 (Aerospace) 16 Feb 18 21:18 Cannot answer simply because: The Tangent Modulus is the slope of the stress-strain curve at a specific point. Therefore it is not a single value, but varies with the stress. At low stresses, the tangent modulus is the same as the normal Young's Modulus. As the stress approaches the yield stress, the modulus decreases, and this local modulus is called the Tangent Modulus. Since you need to know the stress to know the tangent modulus, it becomes an iterative problem. In a nonlinear material analysis, you can define the full stress-strain curve or use a bilinear approximation with a "hardening slope" which reduces the modulus to a constant single value after exceeding the yield stress. RE: AISI 4130 - Tangent modulus sumacon2003 (Structural) (OP) 17 Feb 18 12:17 Thanks sdm919 . I should have clarified. The Tangent modulus was for bilinear-idealization. So the second slope, after reaching the yield point is what I was referring to. SUMATECH, INC. www.sumacon.com RE: AISI 4130 - Tangent modulus rb1957 (Aerospace) 20 Feb 18 14:41 Instead of asking us, plot a stress/strain curve from Et data and fit whatever curve you want. another day in paradise, or is paradise one day closer ?