Table of Contents
What are the causes of residual stress in welding?
Welding residual stresses are caused by differential thermal expansion and contraction of the weld metal and parent material. This is illustrated in Fig. 7.5 for longitudinal residual stresses (transverse residual stresses are also induced, although these generally have compressive and tensile zones within the weld).
What is the effect of residual stress on fatigue failure?
This result suggests that the residual stress in the rollover area strongly affected the fatigue performance of the specimen. In general, a decrease of tensile residual stress or an increase of compressive residual stress improves the fatigue strength of materials.
Why does compressive residual stress increase fatigue?
Low-temperature grinding produces compressive residual stresses and improves fatigue life. This beneficial result is due to the mechanical grinding force applied to the surface which has a similar effect to surface peening.
What are the causes of residual stresses induced during martensitic hardening?
Residual Stresses Due to Quenching
- Quenching/cooling conditions.
- Temperature difference between the surface and the core during the quenching process.
- Temperature interval between the beginning and end of martensite transformation and the cooling rate in this zone.
Why residual stresses are important for engineering applications?
Residual stresses have a significant impact on the propensity for engineering components and structures to undergo fatigue and fracture, with either a positive (life enhancing) or negative (life reducing) effect that is largely dependent on the sign of the residual stress relative to that of the applied stress, i.e. on …
How does residual compressive stress work?
Compressive residual stress can have a very positive impact on fatigue performance because it acts to resist the applied tensile stress as it holds the crack faces shut, minimizing damage. To take advantage of this concept many compressive residual stress surface treatments have been developed.
Is residual stress good?
Effects of residual stress Residual stresses can be beneficial or detrimental, depending on whether the stress is tensile or compressive. Tensile residual stresses can be large enough to cause component distortion or cracking. Also, fatigue and stress corrosion cracking require the presence of tensile stresses.
What happens when internal residual stresses are not removed?
Explanation: When internal residual stresses are not removed, distortion or warpage of the material may occur. Stress relief annealing is carried out to remove these stresses caused by castings, quenching, machining, welding etc.
What is residual stress?
Residual stresses are stresses caused by manufacturing processes. This type od stress remains in a solid material after the original cause of the stresses has been removed. For example, welding leaves residual stresses in the metals welded.
What are residual stress and how do they affect welding?
Residual stresses are those stresses that remain in an object (in particular, in a welded component) even in the absence of external loading or thermal gradients. In some cases, residual stresses result in significant plastic deformation, leading to warping and distortion of an object. In others, they affect susceptibility to fracture and fatigue.
What are residual stresses and how do they affect plastic?
In some cases, residual stresses result in significant plastic deformation, leading to warping and distortion of an object. In others, they affect susceptibility to fracture and fatigue. Click here to see our latest technical engineering podcasts on YouTube. What are the causes? What effects do they have? How can I measure residual stress?
How to reduce residual tensile stresses?
One of the heat treatment processes, stress-relief annealing, can also be used to reduce the residual tensile stresses. The total stress of a component is the sum of the all applied service stresses and residual stresses.