Residual Stress Relief Research Articles

Residual stress relief and local embrittlement in a A533B reactor pressure vessel weldment

A suitable testing technique is developed for evaluating the effect of weld residual stress on fracture toughness in the HAZ region of a reactor pressure vessel steel (SA533 Grade B, Class 1) and for investigating its susceptibility to reheat and underclad cracking or local embrittlement in the coarse-grained HAZs during post weld heat treatment. Use of a fracture mechanics approach leads to an interpretation of the effect of weld residual stress, tempering due to PWHT and notch acuity on the HAZ fracture toughness. This is applied to the estimation of COD transition temperature in the actual component of the reactor pressure vessel in terms of a summation of the various changes in the COD transition temperature associated with several factors such as weld residual stress, tempering, notch acuity and environment. Detailed comments are given on the determination of an allowable crack size in an actual component.

Controlled Surface Flaw‐Initiated Fracture in Reaction‐Densified Silicon Carbide

Controlled surface flaws were produced in commercial reaction‐densified SiC by Knoop microhardness indentation. The flaws themselves could not be observed easily, thus an etching technique was used to delineate their semielliptical shape, thereby enabling calculation of the critical stress‐ intensity factor KIC at room temperature. Room‐temperature fracture was insensitive to annealing environment (air or vacuum), flaw “healing” being observed at ≫1000°C. The variation in fracture stress of indented specimens with temperature showed 3 distinct regions of behavior which were interpreted in terms of residual stress relief, flaw healing, and Si‐SiC bond weakening.

Residual stress relief in cold-extruded rod

AbstractThe residual stresses in cold-extruded mild-steel rods have been estimated by the longitudinal slitting method, and the effect of low-temperature annealing on the residual stress level has been investigated. For the extrusion ratios used (2.78:1 and 4:1), residual stress relief appears first at about 250°C and is substantially complete at about 500°C, the tensile strength having decreased over this temperature range by less than 10%. A correction factor is proposed that allows the determination of residual stresses by the longitudinal slitting method to be independent of slit length.

Use of lasers for the relief of residual welding stresses

Use of lasers for the relief of residual welding stresses

Optimal time and temperature for maximum moment and springback and residual stress relief of stainless steel wire

Optimal time and temperature for maximum moment and springback and residual stress relief of stainless steel wire

On the relation between stress-relief annealing, ordering and stress-corrosion cracking susceptibility in three copper alloys

The effects of post-forming heat treatments on the scc susceptibility in ammoniacal environments of three new commercial copper alloys (CDA Alloys 619, 638 and 688) have been investigated. The stress-corrosion susceptibility was evaluated semi-quantitatively using pre-formed U-bend specimens exposed to environments of moist ammonia and Mattsson's solution. Short time (30 min) heat treatments at various temps. (within the range 250–600°F) were carried out on the preformed U-bend specimens. During subsequent stress-corrosion testing the specimens were stressed elastically, with little further plastic deformation being introduced. The heat treatments used resulted in differing degrees of residual stress relief in the pre-formed U-bend specimens and also in the formation of differing amounts of order in the alloys; these latter effects were evaluated using differential thermal analysis techniques. The stress-corrosion data, expressed as per cent springback with time, are interpreted in terms of the amount of residual stress relief and the degree of ordering. An optimum stress-relief anneal temp. for maximum stress-corrosion resistance of formed components is recommended for each alloy. Results of a metallographic examination of failed specimens are also reported.

Residual stress relief in butt-welded 5083 aluminum alloy by local heating

This paper describes local stress relief heat treatment for butt-joints of a 5083-O plate. The following results were obtained by experiments.(1) In order to relieve the residual stress at a butt-joint, the region of the maximum stress had to be heated at least above 150°C. For relaxing it to about half a degree of as-welded state, the heating had to be above 250°C and for virtually relieving it, the heating above 350°C was needed.(2) Among three heating methods in these experiment, the best results were obtained by the heating method of reciprocation. The results of one or two-point heating method were inferior to those of the above method.(3) The degree of stress relief annealing tended to be similar to the reduction in high temperature tensile strength of the base metal rather than its yield strength.

Improved fibre composite tensile performance by mechanical residual stress relief: ASM Trans Quarterly, Vol 62, No 3, pp 740–748 (1969)

Improved fibre composite tensile performance by mechanical residual stress relief: ASM Trans Quarterly, Vol 62, No 3, pp 740–748 (1969)

Residual Stress and Shape Distortion in High-Strength Tool Steels

AbstractOne of the major problems that has plagued the tool and die maker for many years and more recently has come to the attention of the manufacturer of missiles and high-performance aircraft is the problem of shape distortion which occurs during heat treatment in the high-strength tool and die steels. Not only is shape distortion a problem in the heat treatment and use of these materials, but the origin of shape distortion has been a controversial issue among metallurgists for many years. The quantitative measurement of shape distortion on heat-treated steels is simply carried out hy machining standard shape samples, in this case, an L-shaped sample, and making a measurement of the variation after heat treatment from the 90° of the original 90° angle of the L. It is usually assumed that relief of residual stresses in heat-treated parts will occur by the shape changes which have been described above; however, it has been demonstrated that elastic residual stresses may still be present in heat-treated parts that have been tempered and theoretically should be stress free. By a very straightforward and simple application of the backreflection X-ray diffraction method for residual-stress determination, a very striking relationship has been demonstrated between the shape (angular) distortion of both A2 tool steel (air hardening) and O1 tool steel (oil hardening) and the residualstress pattern of these steels. Conversely, one could presumably utilize residualstress data at changes in cross section to estimate semiquantitatively the amount of shape distortion which occurs in rather complex parts.

Influence of ultrasonic vibrations on the relief of residual stresses during tempering of Kh VG steel

1. When ultrasonic vibrations are transmitted through an oil bath during tempering there is only a slight reduction of the residual stresses in KhVG steel. 2. When the samples are tempered with direct ultrasonic ibrations the residual stresses are reduced sharply. In 0.5 h of treatment with ultrasonic vibrations the residual stresses were reduced to 50% of the initial value, which is equivalent to tempering alone for 2 h at 180°C.

Closure to “Relief of Residual Stresses by Heating Patterns”

Closure to “Relief of Residual Stresses by Heating Patterns”

Discussion of “Relief of Residual Stresses by Heating Patterns”

Discussion of “Relief of Residual Stresses by Heating Patterns”

Discussion of “Relief of Residual Stresses by Heating Patterns”

Discussion of “Relief of Residual Stresses by Heating Patterns”

Relief of Residual Stresses by Heating Patterns

A method is presented for calculating the relief of residual stresses in a rectangular welded plate by local heating. The thermal stresses developed by the local heating patterns are illustrated by graphs. Plastic strain, hence plastic strain gradients, develop when the thermal stress combined with the residual stress exceeds the elastic limit of the material. To calculate the stress field caused by the plastic strains, an analogy between plastic strain gradients and body forces is applied. The Reuss-Mises incremental polyaxial inelastic stress-strain relationship is used. The stress field equation satisfying the conditions of equilibrium, compatibility, and the Reuss-Mises relation of the material are expressed in a system of simultaneous equations in finite difference form, and are solved by a digital computer. The effectiveness of local heating in the relief of residual stress is shown. The method does not require iteration and may be extended to plates of other shapes.

Relief of residual stresses in welded 1Kh18N12T steel pipe

1. To decrease the level of the tensile stresses concentrated in one area of a rigid construction one must heat the neighboring area. 2. The method of relaxation tests of rings with the same resistance to bending should be used to determine the conditions for relief of thermal stresses. 3. Thermal stresses are much easier to relieve than welding stresses after the same stabilization conditions. This is due to the peculiar strength of the melted metal in the weld seam. Welding stresses are removed almost completely at the austenization temperature.

残留応力の不減衰範囲について

In this experiment, we carried out an investigation to find the non-fading region of residual stress. Two kinds of steels, S45C and S35C were used, the former in an oil-quenched and the latter in a low-temperature quenched condition. The residual stress at the surface layers of the two steels was tensile and compressive, respectively. To vary the value of residual stress, mechanical means, i.e. static loading with a uniform bending moment was employed. Taking the residual stress (regarding as a mean stress) as abscissa, and the stress amplitude as ordinate, the non-fading line of residual stress was found to be much less steep than the 45°slope of the yield limit line hitherto considered theoretically, and to be nearly parallel to the line connecting the fatigue limit and the actual breaking stress, both on the tension and compression sides. From this relation, empirical formulas on the non-fading lines were established. After the maximum shear stress law for the relief of residual stress asserted by D. Rosenthal, residual and load maximum shear stresses divided by the yield strength were taken as both axes, and the non-fading lines were represented as 45°slope lines. From these diagrams, the equations of the non-fading lines basing on the yield strength of the material were formulated.

Relief of residual grinding stresses by annealing : H. R. Letner and A. B. Sauvegeot. Metal progress, v. 72, Sept. 1957, p. 79–82

Relief of residual grinding stresses by annealing : H. R. Letner and A. B. Sauvegeot. Metal progress, v. 72, Sept. 1957, p. 79–82

熔接継手の振動特性に及ぼす残留応力の影響

We have studied in this paper on the problem of effect of residual stress on the vibration of welded joints. For the sake of simplicity we have used the so-called "H-type constrained specimen" as shown in Fig. 1 which was made from structural plain cabon steel SS41 of 10mm thick.At first we examined the relief of residual stress due to vibration. Specimen, which was fixed at oneend, was vibrated at constant amplitude and constant frequency, and the residual stress was measuredafter 10, 102, 103, 104 and 105 numbers of vibration respectively. It was known'that the residual stress, initial value of which is about 14-18kg/mm2 in center bar of the specimen, decreased with the increase of numbers of vibration, and after 105 numbers of vibration it became about 50% of the initial value for the case of amplitude 10mm. The magnitude of relieaved stress increase with amplitude. The resultsof this experiment are shown in Figs.3, 4and 5.Nextly we have made the test of free damped vibration of the specimen which was fixed at one end. The frequency and logarithmic decrement of each specimen are shown in Table 3. It is known from this that the frequency decreases with increase of residual stress and the logarithmic decrement is vice versa. At last we have made the test of forced vibration at various number of frequency, and the amplitude of welded specimen was known to be lower than the specimen without weld at the resonance point.

Heat-Treatments of Welded Structures for Relief of Residual Stresses With Particular Reference to Type 347 Stainless-Steel Weldments

Abstract Welded ring samples of Type 347 stainless steel were given a number of different thermal treatments to study their effectiveness in relieving residual stresses. Treatment at temperatures of 1650 F and above caused complete relaxation. At lower temperatures the amount of relaxation obtainable in reasonable periods depended upon the magnitude of the residual stresses. Experiments conducted on twisted Type 347 stainless-steel wire showed that relaxation occurred at low temperatures. A treatment at 1100 F produced some untwisting and established a pattern of residual stresses that did not cause any further movement when the wire was cycled from room temperature at 850 F. High-temperature treatments produce metallurgical changes which may be of greater importance in conditioning the weld for the intended service than the fact that residual welding stresses were relieved. To emphasize the over-all effect of heat-treatments of welded structures, the use of the term “thermal-conditioning” is suggested in place of “stress-relieving.”

Relief of residual stress in streamline tierods

Relief of residual stress in streamline tierods