Content deleted Content added
m →Copper: copyedit (rmv unencyclopedic language) |
m →Steels: Clean up/copyedit |
||
Line 31:
Steel with an ultimate [[tensile strength]] of less than 1000 MPa (~145,000 psi) or hardness of less than [[Hardness comparison|HRC]] 32 on the [[Rockwell scale|Hardness Rockwell Scale]] is not generally considered susceptible to hydrogen embrittlement. As an example of severe hydrogen embrittlement, the elongation at failure of 17-4PH precipitation hardened [[stainless steel]] was measured to drop from 17% to only 1.7% when smooth specimens were exposed to high-pressure hydrogen<ref name="nasa" />
As the [[Strength of materials|strength]] of steels increases, the [[fracture toughness]] decreases, so the likelihood that hydrogen embrittlement will lead to fracture increases. In [[High-strength low-alloy steel|high-strength steels]], anything above a [[hardness]] of HRC 32 may be susceptible to early hydrogen cracking after [[plating]] processes that introduce hydrogen. They may also experience long-term failures any time from weeks to decades after being placed in service due to accumulation of hydrogen over time from [[cathodic protection]] and other sources. Numerous failures have been reported in the hardness range from HRC 32-36 and
Testing the fracture toughness of hydrogen-charged, embrittled specimens is complicated by the need to keep charged specimens very cold, in liquid nitrogen, to prevent the hydrogen diffusing away.<ref name="twitest">[https://www.twi-global.com/technical-knowledge/published-papers/fracture-mechanics-techniques-for-assessing-the-effects-of-hydrogen-on-steel-properties Fracture Mechanics Techniques for Assessing the Effects of Hydrogen on Steel Properties]M J Cheaitani and R J Pargeter, TWI, paper presented at the International Steel and Hydrogen Conference 28 September 2011.</ref>
| |||