Steel. Determination of yield strength increase by the effect of heat treatment (Bake-Hardening-Index)

2015 ◽  
Keyword(s):  
Heat Treatment ◽  
Yield Strength ◽  
Strength Increase ◽  
Bake Hardening

scholarly journals Microstructural Change during the Interrupted Quenching of the AlZnMg(Cu) Alloy AA7050

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2554 ◽  
Author(s):  
Thomas M. Kremmer ◽  
Phillip Dumitraschkewitz ◽  
Daniel Pöschmann ◽  
Thomas Ebner ◽  
Peter J. Uggowitzer ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Yield Strength ◽  
Phase Distribution ◽  
Atom Probe ◽  
Industrial Applications ◽  
Treatment Temperature ◽  
Strength Increase ◽  
Artificial Ageing ◽  
Cu Alloy

This study reports on the effect of interrupted quenching on the microstructure and mechanical properties of plates made of the AlZnMg(Cu) alloy AA7050. Rapid cooling from the solution heat treatment temperature is interrupted at temperatures between 100 and 200 °C and continued with a very slow further cooling to room temperature. The final material’s condition is achieved without or with subsequent artificial ageing. The results show that an improvement in the strength–toughness trade-off can be obtained by using this method. Interrupted quenching at 125 °C with peak artificial ageing leads to a yield strength increase of 27 MPa (538 MPa to 565 MPa) compared to the reference material at the same fracture toughness level. A further special case is the complete omission of an artificial ageing treatment with interrupted quenching at 200 °C. This heat treatment exhibits an 20% increase in fracture toughness (35 to 42 MPa m−1/2) while retaining a sufficient yield strength of 512 MPa for industrial applications. A detailed characterization of the relevant microstructural parameters like present phases, phase distribution and precipitate-free zones is performed using transmission electron microscopy and atom probe tomography.

Effects of a Thermal Coating Process on X100 UOE Line Pipe

2005 ◽  
Author(s):  
Chris Timms ◽  
Duane DeGeer ◽  
Martin McLamb
Keyword(s):  
Heat Treatment ◽  
Yield Strength ◽  
Room Temperature ◽  
High Strength ◽  
Economic Benefits ◽  
Slight Reduction ◽  
Strength Increase ◽  
Coating Process ◽  
Line Pipe ◽  
Heat Treated

The increased demand for high strength linepipe for onshore and offshore pipeline systems has been well documented over the past few years. The economic benefits have been demonstrated, and solutions have been developed to address the technical issues facing high strength linepipe use. However, there are still a few unanswered questions, one of which is addressed in this paper: what is the effect of thermal treatment during the pipeline coating process on the material behaviour of high strength linepipe? This paper presents the results of a thermal coupon study investigating the effects of low temperature heat treatment on the tensile and compressive stress strain curves of samples taken from X100 linepipe. Thirty axial test coupons and thirty circumferential test coupons were machined from a 52 inch diameter, 21 mm wall thickness UOE X100 linepipe. Some of the coupons were maintained in the as-received condition (no heat treatment) while others were heat-treated in a manner that simulates a coating plant induction heat treatment process. All coupons were subsequently tested in tension or compression, either at room temperature or at −18°C. This study has provided a number of interesting results. In regards to material strength, the heat treatment increased the tensile and compressive yield strengths in the longitudinal and circumferential coupons. Axial tensile, axial compressive and circumferential tensile yield strength increases ranged from 5 to 10%. Circumferential compressive yield strength increases ranged from 14 to 24%. A Y/T ratio increase of approximately 7% was observed for all heat-treated tensile coupons. The coupon tests conducted at −18°C were only slightly different than their room temperature counterparts; with an average yield strength increase of 4% in all directions and orientations and a slight reduction in Y/T ratio.

LOCAL USE OF BAKE HARDENING IN MULTIPHASE STEELS FOR IMPROVED PROPERTIES IN STRUCTURES AND JOINTS

2008 ◽  
Vol 07 (02) ◽  
pp. 283-285
Author(s):  
HEINZ PALKOWSKI ◽  
ANNA BRUECK
Keyword(s):  
Heat Treatment ◽  
Automobile Industry ◽  
Steel Structure ◽  
Local Heat ◽  
Processing Parameters ◽  
Local Deformation ◽  
Strength Increase ◽  
Bake Hardening ◽  
Local Heat Treatment ◽  
Multiphase Steels

This paper investigates processes leading to local bake hardening (BH) effects in multiphase steels. The influence of the deformation path and of the temperature and duration of thermal treatments on strengthening in multiphase steels, in regard to both local and bulk properties of steel structure are investigated. Bake hardening is the ability of a metal, to harden during an annealing after forming, for example during the paint baking process in the automobile industry, delivering a post-forming strength increase of the final component. Multiphase steels such as dual phase (DP) and complex phase (CP) steels are investigated to examine the effect of thermo mechanical processing parameters on the local bake hardening ability of hot rolled DP and CP steels. For this purpose two methods of achieving local BH (local deformation and local heat treatment) are studied. The influence of a local deformation through bending on the work hardening, and bake hardening effects is examined. By locally limited laser treatment on cold-rolled material local BH can be reached through local heat treatment. Furthermore, the ageing stability of the gain in strength is examined.

Viability of turbine blade material with a long service life

2019 ◽  
pp. 28-35
Author(s):  
O. B. Berdnik ◽  
I. N. Tsareva ◽  
M. K. Chegurov
Keyword(s):  
Heat Treatment ◽  
Service Life ◽  
Yield Strength ◽  
Mechanical Characteristics ◽  
Operating Time ◽  
Structural Features ◽  
Operating Conditions ◽  
Standard Methods ◽  
Experimental Values ◽  
Plasticity Coefficient

This article deals with structural features and characteristic changes that affect the mechanical characteristics after different service life in real conditions using the example of the blades of the 4th stage of turbine GTE-45-3 with an operating time of 13,000 to 100,000 hours. To study the change in the state of the material under different operating conditions, determine the degree of influence of heat treatment on the regeneration of the microstructure, and restore the mechanical characteristics of the alloy after different periods of operation, non-standard methods were used: relaxation tests on miniature samples to determine the physical yield strength and microplasticity limit and quantitative evaluation of the plasticity coefficient of the material from experimental values of hardness, which allow us to identify the changes occurring in the microvolumes of the material and predict the performance of the product as a whole.

scholarly journals A thermo-mechanical machining method for improving the accuracy and stability of the geometric shape of long low-rigidity shafts

2021 ◽  
Author(s):  
Antoni Świć ◽  
Arkadiusz Gola ◽  
Łukasz Sobaszek ◽  
Natalia Šmidová
Keyword(s):  
Heat Treatment ◽  
Cross Section ◽  
Mechanical Treatment ◽  
Geometric Shape ◽  
Different Dimensions ◽  
Thermo Mechanical Treatment ◽  
Mechanical Machining ◽  
Simultaneous Heat ◽  
Accuracy And Stability

AbstractThe article presents a new thermo-mechanical machining method for the manufacture of long low-rigidity shafts which combines straightening and heat treatment operations. A fixture for thermo-mechanical treatment of long low-rigidity shafts was designed and used in tests which involved axial straightening of shafts combined with a quenching operation (performed to increase the corrosion resistance of the steel used as stock material). The study showed that an analysis of the initial deflections of semi-finished shafts of different dimensions and determination of the maximum corrective deflection in the device could be used as a basis for performing axial straightening of shaft workpieces with simultaneous heat treatment and correction of the initial deflection of the workpiece. The deflection is corrected by stretching the fibers of the stock material, at any cross-section of the shaft, up to the yield point and generating residual stresses symmetrical to the axis of the workpiece. These processes allow to increase the accuracy and stability of the geometric shape of the shaft.

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