scholarly journals Effect of Post-Weld Heat Treatment on the Fatigue Behavior of Medium-Strength Carbon Steel Weldments

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1700
Author(s):  
Byeong-Choon Goo
Keyword(s):  
Heat Treatment ◽  
Yield Strength ◽  
Weld Metal ◽  
Base Material ◽  
Charpy Impact ◽  
Parent Material ◽  
Bogie Frame ◽  
Absorption Energy ◽  
Heat Treated ◽  
Impact Absorption

Railway vehicle makers manufacture the bogie frame by welding medium-strength carbon steel sheets. It has been a long-standing practice to perform post-weld heat treatment (PWHT) to remove welding-residual stress, but rail car manufacturers are moving toward producing bogie frames without PWHT. Since securing the fatigue strength of the bogie frame is essential for vehicle operation safety, it is necessary to systematically evaluate the effects of PWHT on hardness, microstructure, mechanical properties, corrosion, fatigue strength, etc. In this study, small-scale welding specimens and full-size components were produced using S355JR used in general structures, automobiles, shipbuilding, railroad vehicles, etc. The effect of PWHT on material properties-the hardness of the base material, heat-affected zone and weld metal, microstructure, shock absorption energy, yield strength, tensile strength, and fatigue were investigated. When the weld specimen was annealed at 590 °C and 800 °C for 1 h, the yield strength and tensile strength of the specimen decreased, but the elongation increased. For specimens not heat-treated, the parent material’s yield strength, the yield strength in HAZ, and the yield strength of the weld metal were 350 MPa, 345 MPa, and 340 MPa. For specimens heat-treated at 590 °C, they were 350 MPa, 345 MPa, and 340 MPa. For specimens heat-treated at 800 °C, they were 350 MPa, 345 MPa, and 340 MPa. Annealing heat treatment of the specimen at 800 °C homogenized the structure of the weldments similar to that of the base material and slightly improved the shock absorption energy. For specimens not heat-treated, the Charpy impact absorption energies at 20 °C of the parent material and weld metal were 291.5 J and 187 J. For specimens heat-treated at 590 °C, they were 276 J and 166 J. For specimens heat-treated at 800 °C, the Charpy impact absorption energy at 20 °C of the parent material was 299 J. PWHT at 590 °C had the effect of slightly improving the fatigue limit of the specimen but lowered the fatigue limit by 10.8% for the component specimen.

scholarly journals Characteristics of Black Ginseng (Panax ginseng C.A. Mayer) Production Using Ginseng Stored at Low Temperature after Harvest

Metabolites ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 98
Author(s):  
Hyo Bin Oh ◽  
Ji Won Lee ◽  
Da Eun Lee ◽  
Soo Chang Na ◽  
Da Eun Jeong ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Low Temperature ◽  
Panax Ginseng ◽  
Low Temperatures ◽  
Sugar Content ◽  
Base Material ◽  
Free Sugar ◽  
Drying Process ◽  
Heat Treated ◽  
Black Ginseng

Ginseng processing often involves multiple drying and heat treatments. Ginseng is typically processed within one week of harvesting or is stored at low temperatures to prevent spoilage. Black ginseng (BG) is manufactured by repeating the heat treatment and drying process of ginseng several times. We compared the suitability of low-temperature stored ginseng (SG) and harvested ginseng (HG) as the components for black ginseng production. SG and HG were processed into black ginseng and the appearance change, free sugar content, and benzo[a]pyrene (BAP) content were observed. Appearance observations showed the SG to be suitable in terms of quality when heat-treated at a temperature of 95 ℃ or higher. The BAP content of the SG increased significantly as the steaming process was repeated. A maximum BAP concentration of 5.31 ± 1.12 μg/kg was measured in SG steamed from 2 to 5 times, making it unsuitable for processing into BG. SG and HG showed similar trends in the content of sucrose, fructose, and glucose during steaming. This study aimed to facilitate the proper choice of base material to improve the safety of black ginseng by limiting BAP production during processing.

Characterization of Local Deformation in Welded Joints Using a Combined Experimental and Numerical Approach

2014 ◽  
Vol 627 ◽  
pp. 241-244 ◽  
Author(s):  
Pawel Kucharczyk ◽  
Sebastian Münstermann
Keyword(s):  
Chemical Composition ◽  
Weld Metal ◽  
Welded Joints ◽  
Base Material ◽  
Welding Process ◽  
Numerical Approach ◽  
Geometrical Model ◽  
Local Deformation ◽  
Heat Treated ◽  
Welded Structure

The microstructure of welded joints differs significantly from that of the base material, what changes their mechanical properties and influences fatigue life. The aim of this work was the investigation of the local deformation field within a butt joint made of 10 mm thick structural steel S355. However, a direct sampling even of the weld metal was impossible due to small dimensions of butt joints. Therefore, the following procedure was utilized in order to manufacture big samples of the microstructure identical to that of the local weldment areas.A geometrical model of the welded structure describing the relevant areas e.g. weld metal, heat-affected zone was established. It was based on the results of the metallographic investigations, hardness mapping and electron-probe-micro-analysis of the local chemical composition. The welding process was numerically simulated using SYSWELD program to estimate the time-temperature-transition (TTT) curves for each identified area. The parameters of the heat input source were calibrated. Afterwards, the material of the defined chemical composition was heat-treated according to the TTT curves. For the validation purpose the heat-treated work pieces were evaluated in terms of microstructure and hardness distribution. Finally, the up-scaled samples of the respective bulk microstructure were manufactured and investigated in monotonic tests.

Influence of Volume Fraction of Bainite on Mechanical Properties of X80 Pipeline Steel with Excellent Deformability

2011 ◽  
Vol 695 ◽  
pp. 271-274
Author(s):  
Xiao Yong Zhang ◽  
Hui Lin Gao ◽  
Xue Qin Zhang ◽  
Yan Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Yield Strength ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
Dual Phase ◽  
Absorption Energy ◽  
Impact Absorption Energy ◽  
Impact Absorption ◽  
Work Hardening Exponent

The pipeline steel with excellent deformability with ferrite and bainite dual-phase microstructure are obtained by inter-critically accelerating cooling method, aiming to get good deformation capability of avoiding failure from the geological disasters such as landslides and earthquake. The influence of volume fraction of bainite on the mechanical properties of dual-phase pipeline steels was investigated by means of microscopic analysis method and mechanical properties testing. The results indicated that both yield strength and ultimate tensile strength of the steels increase almost linearly with the increasing volume fraction of bainite, while ductility, work hardening exponent and impact absorption energy decrease. When the volume fraction of bainite is about 50%, the yield strength, the yield strength/tensile strength ratio (Y/T), work hardening exponent, uniform elongation and impact absorption energy of X80 pipeline steels with excellent deformability is 665MPa, 0.8, 0.12, 8% and 245J respectively.

Mechanical Behavior of Surface Nitrided and Heat-Treated Laser Welded Ti-6Al-4V

2016 ◽  
Vol 1135 ◽  
pp. 167-178
Author(s):  
Helio Rubens Simoni ◽  
Antonio Jorge Abdalla ◽  
Carlos Antonio Reis Pereira Baptista ◽  
Milton Sergio Fernandes de Lima
Keyword(s):  
Heat Treatment ◽  
Fusion Zone ◽  
Fatigue Behavior ◽  
Base Material ◽  
Nitride Layer ◽  
Zone Structure ◽  
Additional Advantage ◽  
Heat Treated ◽  
Controlled Structure ◽  
Intrinsic Reactivity

The welding of the titanium alloy Ti-6Al-4V has been reported to be difficult because of the intrinsic reactivity with oxygen and also because the weld usually produces an unbalanced α/β structure. This contribution deals with a heat treatment of the laser welded Ti-6Al-4V alloy in a CVD nitriding chamber. The heat treatment aims to obtain a fusion zone structure similar to the base material. An additional advantage of the method is creating a hard nitride layer at the surfaces of the piece, increasing the hardness. The CVD treatment at 850°C per 2 hours proved to be efficient to transform the as-welded martensitic structure to a biphase α/β diffusion controlled structure. Although the fusion zone was soft after the treatment (330 HV), the surface is hard attaining about 750 HV. The tensile strength and ductility after welding were very similar to the base material. However, the yield strength decreased from 1030 MPa to 880 MPa and the uniform strain was reduced from 8 to 1% after the CVD treatment. The fatigue behavior was quite different depending on the testing conditions. For the rotating bending condition, the higher fatigue limits, around 400 MPa, were observed for the CVD-treated weld coupon. However, the fatigue behavior in uniaxial conditions was very similar to the as-welded condition and the CVD-treated weld, attaining the fatigue limits at 250 MPa.

Weld Hardness Study of P91 Welded Pipes with Post Weld Heat Treatment for Elevated Temperature Application in Power Plants

2015 ◽  
Vol 1115 ◽  
pp. 503-508 ◽  
Author(s):  
Muhammad Sarwar ◽  
Mohd Amin bin Abd Majid
Keyword(s):  
Heat Treatment ◽  
Power Plant ◽  
Weld Metal ◽  
Creep Strength ◽  
Power Plants ◽  
Thermal Power ◽  
Base Material ◽  
Welding Process ◽  
Post Weld Heat Treatment ◽  
Weld Heat

The creep strength-enhanced ferritic (CSEF) steels are undergoing an encouraged use around the world especially in power plant construction. On construction sites, it has always been the target to have no problems in welded joints but premature failures are being encountered. The primary reason of these premature failures is found to be the improper heat treatment that is mandatorily carried out to achieve the required weld hardness. Weld hardness has close relationship with creep strength and ductility of the welded structures. Hence it is important for any weld to achieve certain level of weld hardness. This study aims at ascertaining the importance of Post Welding Heat Treatment (PWHT) in achieving the required hardness in creep-strength enhanced ferritic (CSEF) materials.The study was carried out on the welding of alloy steel ASTM A335 Gr. P-91 with the same base material (ASTM A335 Gr. P-91) by Gas Tungsten Arc Welding (GTAW) process using ER90S-B9 filler wire with pre-heat of 200oC (min) and inter-pass temperature of 300oC (max). After welding, the joints were tested for soundness with Radiography testing. Induction heating was used for heat treatment of P91 pipes during welding and post weld heat treatment. The effect of Post Weld Heat Treatment (PWHT) was investigated on the Weld metal and the Heat Affected Zones (HAZ) by hardness testing. It is perceived that the scattered and higher hardness values, more than 250HB in 2” P91 pipes in the weld metal and in the heat affected zones, can be brought into the lower required level, less than 250HB, with an effective post weld heat treatment at 760°C for 2hrs.It is concluded that PWHT is the most effective way of relieving the welding stresses that are produced due to high heat input in the welding process and to achieve the required level of hardness in the weld as well as in the heat affected zones (HAZ) in thermal power plant main steam piping.

Improved Workability of Diameter-Enlarged Process for S35C through Quenching and Tempering Heat Treatment

2019 ◽  
Vol 943 ◽  
pp. 26-33
Author(s):  
Xia Zhu ◽  
Keiji Ogi ◽  
Nagatoshi Okabe
Keyword(s):  
Heat Treatment ◽  
Charpy Impact ◽  
Hardness Test ◽  
Charpy Impact Test ◽  
Medium Carbon Steel ◽  
Medium Carbon ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Deformation Speed ◽  
Quenching And Tempering

The hardness test, Charpy impact test, and axial expansion experiment were performed on a medium carbon steel S35C specimen typically used for shaft materials after first subjecting it to quenching and tempering heat treatment under different heating temperatures/time conditions. The effect of the tempering conditions on the mechanical properties of the specimen and the limit of the diameter-enlarged ratio used for evaluating the workability of the partial diameter-enlarged were investigated. The summary of the results are as follows: after quenching at 880 °C, a fine troostite or sorbite structure was obtained under all heat treatment conditions at heating temperatures of 550 °C to 675 °C, and heating times of 0.5 h to 1.5 h. An improvement was shown in the limit of the diameter-enlarged ratio because the quenching and tempering heat treatment led to an increase in the Charpy impact value/ductility as well as a reduction in the hardness, tensile strength, and yield strength; the partial diameter-enlarged process could be performed on the heat treated material at almost the same deformation speed as a cold-drawn material with a much lower axial pressure; it was possible to estimate the diameter-enlarged deformation behavior using the tempering parameter M. We confirmed that the quenching tempering heat treatment performed in this study facilitates the improvement of the workability of the diameter-enlarged.

Effects of semi-solid extrusion and heat treatment on the microstructure, mechanics, and wear resistance of SiC/High aluminum zinc-base alloy composites

2020 ◽  
Vol 34 (25) ◽  
pp. 2050261
Author(s):  
Yingwu Wang ◽  
Xiaoqing Zuo ◽  
Songjiang Ran ◽  
Yushun Ye ◽  
Jihua Tian
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Wear Resistance ◽  
Yield Strength ◽  
Base Alloy ◽  
Extrusion Temperature ◽  
Heat Treated ◽  
Semi Solid ◽  
High Aluminum

The effects of semi-solid extrusion temperature change, extrusion pressure, SiC content and T5 heat treatment on the microstructure, mechanical properties, and wear resistance of SiC particle strengthened high aluminum zinc-base alloy [Formula: see text] composites were studied. The results show that semi-solid extrusion broke the dendrites of [Formula: see text] composites, refined their grain structure, and improved particle aggregation. The density, hardness, yield strength, tensile strength and elongation of [Formula: see text] composites first increased and then decreased when the extrusion temperature and SiC content increased, and also increased when the extrusion pressure rose. The optimal extrusion temperature, pressure and SiC content are 475[Formula: see text], 15 MPa and 10 wt.%, respectively. T5 heat treatment further refined the crystalline grains and promoted [Formula: see text] and [Formula: see text] to precipitate as strengthening phases, which improve the mechanical properties and wear resistance of [Formula: see text] composites. Consequently, the hardness, yield strength, tensile strength and elongation of the heat-treated composites improved by 18.99%, 9.66%, 4.93% and 9.76%, respectively. The wear loss of the heat-treated composites reduced by 31.65% under a load of 1600 N and a rotational speed of 200 r/min compared with the as-cast composites.

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.

Chemical, Structural, Mechanical and Intergranular Corrosion Characterization of Welded Pipes Joints Made of TP 347 Steel

2013 ◽  
Vol 291-294 ◽  
pp. 2594-2604
Author(s):  
Doru Romulus Pascu ◽  
Roşu Radu Alexandru ◽  
Fulga Doru ◽  
Duma Iuliana
Keyword(s):  
Heat Treatment ◽  
Base Metal ◽  
Welded Joints ◽  
Intergranular Corrosion ◽  
Base Material ◽  
Chemical Compositions ◽  
Base Materials ◽  
Heat Treated ◽  
Complex Carbides ◽  
Precision Temperature

The paper presents the experimental results obtained on the pipes welded joints made of TP 347 steel in normal state, NT (welded) and heat-treated state, TT for post-welding stabilization. Heat treatment for stabilization was performed in an electric furnace which provided the process parameters (Theat = 900°C, Vheat = vcooling ≈ 300°C, etc.) and a precision temperature of ±10°C to 1000°C. Chemical compositions of TP 347 steel pipe and of the filler material (ER 347) have values falling within the manufacturing standards (Cr = 17 ... 19% and Ni = 9... 13%). In the specific areas of the welded joints were detected austenitic structures with heterophasic areas of ferrite and complex carbides areas, having the hardness between 162 and 225 HV10. No welding and heat treatment defects were detected, such as cracks and microcracks. The mechanical strength (Rp0,2 and Rm), determined on the base metal and on the welded joints presents high values. Thus, for the base metal were obtained values of Rp0,2 of minimum 212 N/mm2, respectively values of minimum 523 N/mm2 for Rm. For the welded joints, Rm has values between 522 N/mm2 and 527 N/mm2. All the values obtained are higher than those required by ASTM A370standard. The base materials in NT and TT state presents high values of impact energy KV at 20°C, between 72J and 78J, and for the welded joints, the values of KV are between 53J and 60J, with ductile breaking aspect of the specimens’surfaces. The surfaces of the tested specimens for resistance to intergranular corrosion according to ASTM A 262-2010, Method E, presented not specific defects, attesting a corresponding behavior of the intergranular corrosion of TP347 steel and of the welded joints made of the pipes having the dimensions of ø219 x 8.18 mm. The values of the chemical, structural, mechanical and intergranular corrosion characteristics determined on specific samples evidence a high quality of the base material and of the welded joints of TP 347steel pipe, conducted by qualified welding technology, commonly used in the manufacture of components from chemical and petrochemical industries.

The Causes of Low Impact Strength of T23 Steel Weld Joints

2015 ◽  
Vol 226 ◽  
pp. 103-106
Author(s):  
Janusz Adamiec ◽  
Izabela Pikos ◽  
Michał Stopyra
Keyword(s):  
Heat Treatment ◽  
Impact Strength ◽  
Weld Metal ◽  
Post Weld Heat Treatment ◽  
Weld Joints ◽  
Heat Treated ◽  
Heat Treated Condition ◽  
The Impact ◽  
Welding Technique ◽  
Weld Heat

T23 is modern bainitic steel designed for use in supercritical boilers. According to producer’s data weldability of this steel is good enough to avoid post-weld heat treatment. However, some of the T23 weld joints in as-welded condition have not met the minimal ductility requirement. The impact test revealed significant differences between the joints in as-welded and heat treated condition. Metallographic and fractographic examinations have been conducted in order to explain those differences. The specimens with low impact strength were characterized by brittle fracture and non-tempered martensite presence in weld metal. It was concluded that avoiding formation of disadvantageous structure in weld metal requires conducting of post weld heat treatment or applying multi-pass welding technique with annealing run.

Sign in / Sign up

Export Citation Format

Share Document