Assessment of Retained Austenite in Fine Grained Inductive Heat Treated Spring Steel

Advanced thermomechanical hot rolling is becoming a widely used technology for the production of fine-grained spring steel. Different rapid phase transformations during the inductive heat treatment of such steel causes the inhomogeneous mixture of martensitic, bainitic, and austenitic phases that affects the service properties of the steel. An important task is to assess the amount of retained austenite and its distribution over the cross-section of the inductive quenched and tempered wire in order to evaluate the mechanical properties of the material. Three different analytical methods were used for the comparative quantitative assessment of the amount of retained austenite in both the core and rim areas of the sample cross-section: neutron diffraction—for the bulk of the material, Mössbauer spectroscopy—for measurement in a surface layer, and the metallographic investigations carried by the EBSD. The methods confirmed the excessive amount of retained austenite in the core area that could negatively affect the plasticity of the material.

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On the Q&P Potential of a Commercial Spring Steel

Metals ◽

10.3390/met11101612 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1612

Author(s):

Markus Härtel ◽

Alisa Wilke ◽

Sebastian Dieck ◽

Pierre Landgraf ◽

Thomas Grund ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Retained Austenite ◽

Volume Fraction ◽

Electron Backscatter Diffraction ◽

Tensile Tests ◽

Spring Steel ◽

Process Window ◽

Compression Tests ◽

Process Step

Over the last years heat treatment concept of “quenching and partitioning” (Q&P) has reached popularity for its ability to precisely adjust material properties to desired values. Mostly, Q&P process are applied on tailor-made materials with high purities or prototype alloys. The research in hand presents the whole routine of how to investigate the potential of a commercial 0.54C-1.45Si-0.71Mn spring steel in terms of Q&P heat treatment from lab scale in dilatometer measurements to widely used inductive heat treatment on larger scale. In order to obtain the small process window for this material we were focusing on the interplay of the formed microstructure and the resulting mechanical properties in hardness measurements, compression tests as well as tensile tests. After full austenitizing, three different Q&P processing routes were applied. Microstructural analyses by optical microscopy, Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction (EBSD) exhibit a condition with 6.4 % and 15 % volume fraction of fine distributed retained austenite. Interestingly, the 15 % of retained austenite developed during the partitioning heat treatment. Contradictory to our expectations, tensile and compression testing were showing that the 6.4 % condition achieved improved mechanical properties compared to the 15 % retained austenite condition. The remarkable conclusion is that not only volume fraction and fine distribution of retained austenite determines the potential of improving mechanical properties by Q&P in commercial alloys: also the process step when the retained austenite is developing as well as occurring parallel formation of carbides may strongly influence this potential.

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Influence of Post Weld Heat Treatment on the Grain Size, and Mechanical Properties of the Alloy-800H Rotary Friction Weld Joints

Materials ◽

10.3390/ma14164366 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4366

Author(s):

Saqib Anwar ◽

Ateekh Ur Rehman ◽

Yusuf Usmani ◽

Ali M. Al-Samhan

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Grain Size ◽

Heat Affected Zone ◽

Tensile Testing ◽

Weld Zone ◽

Alloy 800H ◽

Weld Joints ◽

Heat Treated ◽

Friction Weld

This study evaluated the microstructure, grain size, and mechanical properties of the alloy 800H rotary friction welds in as-welded and post-weld heat-treated conditions. The standards for the alloy 800H not only specify the composition and mechanical properties but also the minimum grain sizes. This is because these alloys are mostly used in creep resisting applications. The dynamic recrystallization of the highly strained and plasticized material during friction welding resulted in the fine grain structure (20 ± 2 µm) in the weld zone. However, a small increase in grain size was observed in the heat-affected zone of the weldment with a slight decrease in hardness compared to the base metal. Post-weld solution heat treatment (PWHT) of the friction weld joints increased the grain size (42 ± 4 µm) in the weld zone. Both as-welded and post-weld solution heat-treated friction weld joints failed in the heat-affected zone during the room temperature tensile testing and showed a lower yield strength and ultimate tensile strength than the base metal. A fracture analysis of the failed tensile samples revealed ductile fracture features. However, in high-temperature tensile testing, post-weld solution heat-treated joints exhibited superior elongation and strength compared to the as-welded joints due to the increase in the grain size of the weld metal. It was demonstrated in this study that the minimum grain size requirement of the alloy 800H friction weld joints could be successfully met by PWHT with improved strength and elongation, especially at high temperatures.

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Effect of Si Content on Microstructure and Properties of 60Si2CrVA Spring Steel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.968.63 ◽

2014 ◽

Vol 968 ◽

pp. 63-66 ◽

Cited By ~ 1

Author(s):

Fei Zhao ◽

Zhan Ling Zhang ◽

Jun Shuai Li ◽

Cui Ye ◽

Ni Li

Keyword(s):

Mechanical Properties ◽

Retained Austenite ◽

Volume Fraction ◽

Testing Machine ◽

Spring Steel ◽

Impact Testing ◽

X Ray ◽

Comprehensive Properties ◽

Spring Steels ◽

Si Content

The microstructure and mechanical properties of the four spring steels with different Si content treated by Q-I-Q-T process were studied by metallographic microscope, MTS, impact testing machine and X-ray stress analyzer. The results show that the tensile strength and yield strength is first increased and then decreased with the increase of Si content, the volume fraction of retained austenite and elongation are fist decreased and then increased when the Si content is less than 2.1%, and the microstructure become finer and homogeneous. When Si content reaches 2.1%, the comprehensive properties of 60Si2CrVA spring steel is the best.

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Application of Tailored Heat Treated Blanks under Quasi Series Conditions

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.344.383 ◽

2007 ◽

Vol 344 ◽

pp. 383-390 ◽

Cited By ~ 3

Author(s):

Marion Merklein ◽

Uwe Vogt

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Local Heat ◽

Strength Distribution ◽

Process Window ◽

Short Term ◽

Forming Process ◽

Heat Treated ◽

Set Up ◽

The Impact

Tailored Heat Treated Blanks (THTB) are blanks that exhibit locally different strength specifically optimized for the succeeding forming process. The strength distribution is set by a local, short-term heat treatment modifying the mechanical properties of the material. Hence, THTB allow enhancing forming limits significantly leading to shorter and more robust manufacture process chains. In order to qualify the use of THTB under quasi series conditions, the interdependencies of the blank’s local heat treatment and the entire process chain of the car body manufacture have to be analyzed. In this respect, the impact of a short-term heat treatment on the mechanical properties of AA6181PX, a commonly used aluminum alloy in today’s car bodies, was studied. Also the influence of a short-term heat treatment on the coil lubricant, usually already applied by the material supplier, was given a closer look. Based on these experiments process restrictions for the application of THTB in an industrial automotive environment were derived and a process window for the THTB design was set up. In conclusion, strategies were defined how to enhance the found process boundaries leading to a more robust process window.

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Effects of Cryogenic Treatment on the Microstructure and Mechanical Properties of High-alloyed Tool Steels

HTM Journal of Heat Treatment and Materials ◽

10.1515/htm-2020-750505 ◽

2020 ◽

Vol 75 (5) ◽

pp. 73-93

Author(s):

Alwin Schulz ◽

Chengsong Cui ◽

Matthias Steinbacher ◽

Tuncer Ümit ◽

Martin Wunde ◽

...

Keyword(s):

Mechanical Properties ◽

Wear Resistance ◽

Retained Austenite ◽

Cryogenic Treatment ◽

Homogeneous Distribution ◽

Tool Steels ◽

Positive Effects ◽

Heat Treated ◽

Primary Carbides ◽

Complete Transformation

Abstract In this work, the influence of a cryogenic treatment on the microstructure, mechanical properties and wear resistance of the high-alloyed tool steels X38CrMoV5-3, X153CrMoV12 and ~X190CrVMo20-4 were investigated. Based on tempering curves of the steels, the heat treatment parameters were determined for the mechanical and wear specimens so that the conventionally heat-treated steels and the cryogenically treated steels featured similar hardness. The investigations showed that an almost complete transformation of retained austenite and a more homogeneous distribution of secondary carbides in the microstructure could be achieved by incorporating a cryogenic treatment. However, the cryogenic treatment does not show significantly positive effects on the investigated mechanical properties and wear resistance of the tool steels. The wear resistance of the samples was dominated by primary carbides. The cryogenic treatment would have a positive effect on large tool components with large wall thicknesses in terms of uniform and complete transformation of retained austenite throughout the entire components.

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Effect of heat treatment on mechanical properties of 3D printed polylactic acid parts

Materials Testing ◽

10.1515/mt-2020-0010 ◽

2021 ◽

Vol 63 (1) ◽

pp. 73-78

Author(s):

Pulkin Gupta ◽

Sudha Kumari ◽

Abhishek Gupta ◽

Ankit Kumar Sinha ◽

Prashant Jindal

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Polylactic Acid ◽

Recrystallization Temperature ◽

Fused Deposition Modelling ◽

Fused Deposition ◽

Dog Bone ◽

Heat Treated ◽

Maximum Decrease ◽

3D Printed

Abstract Fused deposition modelling (FDM) is a layer-by-layer manufacturing process type of 3D-printing (3DP). Significant variation in the mechanical properties of 3D printed specimens is observed because of varied process parameters and interfacial bonding between consecutive layers. This study investigates the influence of heat treatment on the mechanical strength of FDM 3D printed Polylactic acid (PLA) parts with constant 3DP parameters and ambient conditions. To meet the objectives, 7 sets, each containing 5 dog-bone shaped samples, were fabricated from commercially available PLA filament. Each set was subjected to heat treatment at a particular temperature for 1 h and cooled in the furnace itself, while one set was left un-treated. The temperature for heat treatment (Th) varied from 30 °C to 130 °C with increments of 10 °C. The heat-treated samples were characterized under tensile loading of 400 N and mechanical properties like Young’s modulus (E), Strain % ( ε ) and Stiffness (k) were evaluated. On comparing the mechanical properties of heat-treated samples to un-treated samples, significant improvements were observed. Heat treatment also altered the geometries of the samples. Mechanical properties improved by 4.88 % to 10.26 % with the maximum being at Th of 110 °C and below recrystallization temperature (Tr) of 65 °C. Deformations also decreased significantly at higher temperatures above 100 °C, by a maximum of 36.06 %. The dimensions of samples showed a maximum decrease of 1.08 % in Tr range and a maximum decrease of 0.31 % in weight at the same temperature. This study aims to benefit the society by establishing suitable Th to recover the lost strength in PLA based FDM 3D printed parts.

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Influence of Heat Treatment on Microstrudture and Mechanical Properties of AZ31B Magnesium Alloy Prepared by Solid-State Recycling

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.271-272.17 ◽

2012 ◽

Vol 271-272 ◽

pp. 17-20

Author(s):

Shu Yan Wu ◽

Ze Sheng Ji ◽

Chun Ying Tian ◽

Ming Zhong Wu

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Solid State ◽

Magnesium Alloy ◽

Static Recrystallization ◽

Annealing Treatment ◽

Az31b Magnesium Alloy ◽

Heat Treated ◽

Elongation To Failure ◽

Strength And Ductility

This work is to study the influence of heat treatment on microstrudture and mechanical properties of AZ31B magnesium alloy prepared by solid -state recycling. AZ31B magnesium alloy chips were recycled by hot extruding. Three different heat treatments were conducted for recycled alloy. Mechanical properties and microstructure of the recycled specimen and heat treated specimen were investigated. 300°C×2h annealing specimen exhibits finer grain due to static recrystallization, and microstructure of 400°C×2h annealing specimen becomes more coarse. 300°C×2h annealing treatment improves obviously strength and ductility of recycled alloy. Ultimate tensile strength of alloy decreases and elongation to failure increases after 400°C×2h annealing. Grain size, dislocation density and bonding of chips have an effect on the elongation of recycled materials. 190°C×8h ageing has no influence on microstructure and mechanical properties of recycled alloy.

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Electron Beam Melting of Ti-6Al-4V Lattice Structures; Correlation between Post Heat Treatment and Mechanical Properties

10.21203/rs.3.rs-248635/v1 ◽

2021 ◽

Author(s):

Giuseppe Del Guercio ◽

Manuela Galati ◽

Abdollah Saboori

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Computer Aided Design ◽

Mechanical Performance ◽

Industrial Applications ◽

Heat Treatments ◽

Layer By Layer ◽

Lattice Structures ◽

Heat Treated ◽

Aided Design

Abstract Additive Manufacturing processes are considered advanced manufacturing methods. It would be possible to produce complex shape components from a Computer-Aided Design model in a layer-by-layer manner. Lattice structures as one of the complex geometries could attract lots of attention for both medical and industrial applications. In these structures, besides cell size and cell type, the microstructure of lattice structures can play a key role in these structures' mechanical performance. On the other hand, heat treatment has a significant influence on the mechanical properties of the material. Therefore, in this work, the effect of the heat treatments on the microstructure and mechanical behaviour of Ti-6Al-4V lattice structures manufactured by EBM was analyzed. The main mechanical properties were compared with the Ashby and Gibson model. It is very interesting to notice that a more homogeneous failure mode was found for the heat-treated samples. The structures' relative density was the main factor influencing their mechanical performance of the heat-treated samples. It is also found that the heat treatments were able to preserve the stiffness and the compressive strength of the lattice structures. Besides, an increment of both the elongation at failure and the absorbed energy was obtained after the heat treatments. Microstructure analysis of the heat-treated samples confirms the increment of ductility of the heat-treated samples with respect to the as-built one.

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PROPERTIES OF PARTICLEBOARD PANELS MADE OF SUGARCANE PARTICLES WITH AND WITHOUT HEAT TREATMENT

Revista Árvore ◽

10.1590/1806-90882019000500002 ◽

2019 ◽

Vol 43 (5) ◽

Author(s):

Emerson Gomes Milagres ◽

Raiana Augusta Grandal Savino Barbosa ◽

Karine Fernandes Caiafa ◽

Gabriel Soares Lopes Gomes ◽

Tatiana Aurora Condezo Castro ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Sugarcane Bagasse ◽

Linear Expansion ◽

Basic Density ◽

Water Vapor Adsorption ◽

Thickness Swelling ◽

Specific Mass ◽

Heat Treated ◽

Significant Difference

ABSTRACT The objective of this work was to determine the properties of particleboard panels made of “in natura” sugarcane bagasse particles, heated at 250 °C for 5 minutes. Various particle proportions were utilized to produce the panels and their properties were compared with that of a panel made of Pinus sp. The panels were produced with 8% tannin formaldehyde adhesive, and 0.5% paraffin emulsion, being pressed at 32 kgf.cm-2 for 10 minutes at 180 ° C. It was determined the basic density of the “in natura” and heat-treated particles, their chemical composition, as well as the compression ratio necessary to obtain panels with density equal to 0.75 g.cm-3. The basic density of the panels, hygroscopic equilibrium humidity, thickness swelling, linear expansion, water vapor adsorption, modulus of elasticity and rupture, perpendicular traction, screw pullout, and Janka hardness were determined. The basic densities of Pinus particles and sugarcane bagasse without and with heat treatment were 0.46, 0.27 and 0.30 g.cm-3, respectively. The average specific mass of the panels was 0.74 g.cm-3 with no significant difference between them. Generally, panels made of sugarcane particles were less hygroscopic and dimensionally more stable than panels made of Pinus particles. However, the perpendicular tensile strength, screw pullout and Janka hardness of these panels were higher than for the Pinus panels. The heat treatment of sugarcane bagasse particles resulted in better mechanical properties of perpendicular traction and Janka hardness. In general, the panels are within the limits set by ANSI A208.1. It is therefore possible to replace panels made of Pinus particles for the ones made of sugarcane bagasse, provided that at least 25% of the particles are heat treated for 5 minutes at 250 ° C.

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Study on the Effect of High-Temperature Heat Treatment on the Microscopic Pore Structure and Mechanical Properties of Tight Sandstone

Geofluids ◽

10.1155/2021/8886186 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Liangbin Dou ◽

Guanli Shu ◽

Hui Gao ◽

Jinqing Bao ◽

Rui Wang

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Pore Structure ◽

Water Cooling ◽

Tight Sandstone ◽

The Core ◽

Core Samples ◽

High Temperature Heat Treatment ◽

Different Temperatures ◽

Cooling Methods

The investigation of changes in physical properties, mechanical properties, and microscopic pore structure characteristics of tight sandstone after high-temperature heat treatment provides a theoretical basis for plugging removal and stimulation techniques, such as high energy gas fracturing and explosive fracturing. In this study, core samples, taken from tight sandstone reservoirs of the Yanchang Formation in the Ordos Basin, were first heated to different temperatures (25-800°C) and then cooled separately by two distinct cooling methods—synthetic formation water cooling and natural cooling. The variations of wave velocity, permeability, tensile strength, uniaxial compressive strength, and microscopic pore structure of the core samples were analyzed. Experimental results demonstrate that, with the rise of heat treatment temperature, the wave velocity and tensile strength of tight sandstone decrease nonlinearly, yet its permeability increases nonlinearly. The tight sandstone’s peak strength and elastic modulus exhibit a trend of the first climbing and then declining sharply with increasing temperature. After being treated by heat at different temperatures, the number of small pores varies little, but the number of large pores increases obviously. Compared to natural cooling, the values of physical and mechanical properties of core samples treated by synthetic formation water cooling are apparently smaller, whereas the size and number of pores are greater. It can be explained that water cooling brings about a dramatic reduction of tight sandstone’s surface temperature, generating additional thermal stress and intensifying internal damage to the core. For different cooling methods, the higher the core temperature before cooling, the greater the thermal stress and the degree of damage caused during the cooling process. By taking into consideration of changes in physical properties, mechanical properties, and microscopic pore structure characteristics, the threshold temperature of tight sandstone is estimated in the range of 400-600°C.

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