Cause and Prevention of Stress-Relief Cracking in Quenched and Tempered Steel Weldments

1972 ◽  
Vol 94 (1) ◽  
pp. 336-341 ◽  
Author(s):  
C. F. Meitzner
Keyword(s):  
High Temperature ◽  
Heat Affected Zone ◽  
Elevated Temperatures ◽  
Stress Relief ◽  
Heat Treatments ◽  
Intergranular Cracking ◽  
Quenched And Tempered Steel ◽  
Postweld Heat ◽  
Tempered Steel

The paper reviews the causes and characteristics of stress-relief cracking, i.e., intergranular cracking in the heat-affected zone that occurs during the exposure of welded assemblies to the elevated temperatures produced by postweld heat treatments or high-temperature service. The findings presented are based largely on work at the Homer Research Laboratories with quenched and tempered steels. Means for preventing cracking during fabrication and service are discussed.

Creep Rupture Properties of High-Temperature Bainitic Steels After Weld Repair

2000 ◽  
Vol 122 (3) ◽  
pp. 259-263 ◽  
Author(s):  
J. E. Indacochea ◽  
G. Wang ◽  
R. Seshadri ◽  
Y. K. Oh
Keyword(s):  
High Temperature ◽  
Heat Affected Zone ◽  
Elevated Temperatures ◽  
Rupture Life ◽  
Creep Rupture ◽  
Welding Parameters ◽  
Structure Stability ◽  
Rotor Steel ◽  
Bainitic Steels ◽  
Alloy Steels

Welded high-temperature power plant components can experience a greater risk of failure by creep during service, when compared to similar as-wrought components. The heat-affected zone (HAZ) of alloy steels is usually the region of a weldment exhibiting poor mechanical properties. The arc welding of an ASTM A470, Class 8-rotor steel in this study identified the intercritical heat affected zone (ICHAZ) as the weakest region in terms of creep rupture life. The type of welding procedure significantly affects this region, but most important are the welding parameters utilized. Because of the microstructural heterogeneity of the HAZ and sensitivity of these microstructures to changes when exposed to elevated temperatures, their performance at later times is difficult to predict. Extrapolation techniques are limited in value for predicting service lives of homogeneous materials, because these do not incorporate the microstructure changes of the materials during high temperature operation. They are even less useful for predicting the operating lives of weldments. This paper considers the creep performance and structure stability of the ICHAZ of 12 percent Cr and 214-1Mo vanadium modified weldments produced on a retired CrMoV rotor steel. [S0094-4289(00)00303-0]

Study on Anti-Corrosion of the HAZ of 30CrMnSi Treated by Laser Remelting

2011 ◽  
Vol 291-294 ◽  
pp. 1421-1424 ◽  
Author(s):  
Yan Li Li ◽  
Ren Xu Huang ◽  
Pei Zhong Zhao ◽  
De Xian Yi
Keyword(s):  
Mechanical Properties ◽  
Laser Treatment ◽  
Heat Affected Zone ◽  
Processing Parameters ◽  
Corrosion Property ◽  
Laser Remelting ◽  
Corrosion Properties ◽  
Yag Laser ◽  
Quenched And Tempered Steel ◽  
Tempered Steel

30CrMnSi is quenched and tempered steel with medium hardenability, and good mechanical properties. However, the anti-corrosion of the weld heat affected zone will be decreased, which will lead to the worse overall properties of parts. The anti-corrosion properties of heat affected zone will be improved by YAG laser treatment according optimized processing parameters. The microstructure of the modified heat affected zone was observed and analyzed in this paper. And the anti-corrosion property was studied also. The results showed that the anti-corrosion property of heat affected zone will be improved by laser remelting technology. The laser anti-corrosion is the effective method to enhance anti-corrosion property.

Cracking in Grade 23 Weldments at Elevated Temperatures

2014 ◽  
Author(s):  
Jude R. Foulds ◽  
John A. Siefert
Keyword(s):  
Heat Affected Zone ◽  
Large Scale ◽  
Elevated Temperatures ◽  
Compact Tension ◽  
Life Assessment ◽  
Intergranular Cracking ◽  
Cracking Behavior ◽  
Post Test ◽  
Furnace Tube ◽  
Lower Test

Recent, brittle fracture in Grade 23 power plant components at relatively low temperatures has increased the need to assess the cracking behavior of this material. Time-dependent cracking in the heat-affected zone of Grade 23 weldments was assessed using crack growth testing of subsize compact tension specimens at a temperature (482°C, 900°F) characteristic of the upper portion of a furnace wall in supercritical boilers. Results of additional testing at a higher, typical design temperature (566°C, 1050°F) for superheater and reheater tubing and headers will be reported later. Post-test metallurgical evaluation of the cracking morphology was conducted using traditional light microscopy and laser microscopy. Although large-scale creep deformation is absent under these lower test temperature conditions, significant weldment heat-affected zone intergranular cracking was documented. An example of application of the data to the inservice integrity and life assessment of a furnace tube is also described, providing preliminary perspective on the factors controlling lifetime and manageability of integrity. Paper published with permission.

Microstructure modeling of high-temperature microcrack initiation and evolution in a welded 9Cr martensitic steel

2019 ◽  
Vol 233 (10) ◽  
pp. 2160-2174
Author(s):  
M Li ◽  
PE O'Donoghue ◽  
SB Leen
Keyword(s):  
High Temperature ◽  
Crystal Plasticity ◽  
Heat Affected Zone ◽  
Elevated Temperatures ◽  
Element Model ◽  
Plasticity Model ◽  
Welded Steel ◽  
Premature Failure ◽  
Crystal Plasticity Model ◽  
Microcrack Initiation

Welded joints in tempered 9Cr–1Mo operating at elevated temperatures are well known to be prone to premature failure due to cracking in the heat-affected zone. This paper describes a crystal plasticity model to predict the microcrack initiation and evolution in the inter-critical heat-affected zone of 9Cr–1Mo welded steel at elevated temperature. A crystal plasticity finite element model indicates that the micro-cracks of 9Cr–1Mo steel mostly nucleate at prior austenite grain boundaries and boundary clustered regions. Inter-granular and trans-granular microcracking are shown to be the key predicted microdamage mechanisms from the current crystal plasticity model. A small amount of ferrite in the inter-critical heat-affected zone is shown to not only influence the microcrack initiation and evolution, but also significantly accentuate material degradation for a given applied load leading to premature failure at high temperature.

High-Temperature Instability of A Cr2Nb-Nb(Cr) Microlaminate Composite

1996 ◽  
Vol 54 ◽  
pp. 374-375
Author(s):  
M. Larsen ◽  
R.G. Rowe ◽  
D.W. Skelly
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Aircraft Engine ◽  
Lattice Parameter ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Cross Sectional ◽  
Bcc Structure

Microlaminate composites consisting of alternating layers of a high temperature intermetallic compound for elevated temperature strength and a ductile refractory metal for toughening may have uses in aircraft engine turbines. Microstructural stability at elevated temperatures is a crucial requirement for these composites. A microlaminate composite consisting of alternating layers of Cr2Nb and Nb(Cr) was produced by vapor phase deposition. The stability of the layers at elevated temperatures was investigated by cross-sectional TEM.The as-deposited composite consists of layers of a Nb(Cr) solid solution with a composition in atomic percent of 91% Nb and 9% Cr. It has a bcc structure with highly elongated grains. Alternating with this Nb(Cr) layer is the Cr2Nb layer. However, this layer has deposited as a fine grain Cr(Nb) solid solution with a metastable bcc structure and a lattice parameter about half way between that of pure Nb and pure Cr. The atomic composition of this layer is 60% Cr and 40% Nb. The interface between the layers in the as-deposited condition appears very flat (figure 1). After a two hour, 1200 °C heat treatment, the metastable Cr(Nb) layer transforms to the Cr2Nb phase with the C15 cubic structure. Grain coarsening occurs in the Nb(Cr) layer and the interface between the layers roughen. The roughening of the interface is a prelude to an instability of the interface at higher heat treatment temperatures with perturbations of the Cr2Nb grains penetrating into the Nb(Cr) layer.

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