Effect of Heat Treatment on Impact Toughness of Selective Laser Melted Stainless Steel Parts

2018 ◽  
Author(s):  
Sagar Sarkar ◽  
Soumya Dubey ◽  
Ashish Kumar Nath
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stainless Steel ◽  
Impact Toughness ◽  
Thermal Loading ◽  
Processing Technique ◽  
Layer By Layer ◽  
Solution Annealing ◽  
Tem Analysis ◽  
Suitable Heat Treatment

One of the versatile additive manufacturing processes is laser based Selective Laser Melting (SLM) which allows to build complex intricate shapes directly from its three dimensional digital images. Layer by layer deposition and depending upon build orientations, SLM parts tends to be anisotropic in nature. Also non-uniformity in thermal loading across the part leads to inhomogeneous microstructure which may have detrimental effect on various mechanical properties. Heat treatment of as-built SLM parts could be used as a post processing technique to reduce the anisotropy and produce homogenous microstructure to ensure reproducible mechanical properties. Application oriented mechanical properties can be obtained for precipitation hardened stainless steel by suitable heat treatment process. Present study is based on effect of heat treatments namely solution annealing, ageing and overaging on impact toughness of SLM 15-5 PH stainless steel. In order to support experimental observations, various metallurgical techniques have been applied. Effect of notch orientations causes anisotropy in impact toughness but this anisotropy is reduced with application of suitable heat treatment. In case of ageing, Transmission Electron Microscopy (TEM) analysis shows formation of fine spherical Cu precipitates which solution strengthens but makes the specimen brittle. As a result relatively lower impact toughness is obtained as compared to overaged condition where combined effect of coarsening of Cu precipitates and increased retained austenite makes the specimen ductile. Increased ageing temperature and soaking time does not have significant effect on impact toughness. However, solution annealing before ageing is recommended for homogenous precipitation throughout the specimen and statistically less scattered data. In all the cases SLM specimens have lower impact toughness to that of cold rolled 15-5 PH stainless steel. Present study could be used as a guideline to get application oriented mechanical properties mainly impact toughness.

Effect of Different Heat Treatments on Mechanical Properties of Laser Sintered Additive Manufactured Parts

2017 ◽  
Author(s):  
Sagar Sarkar ◽  
Cheruvu Siva Kumar ◽  
Ashish Kumar Nath
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Yield Strength ◽  
Tensile Strain ◽  
Wear Loss ◽  
Layer By Layer ◽  
Solution Annealing ◽  
Wear Properties ◽  
Sem Images ◽  
Wide Range

One of the most popular additive manufacturing processes is laser based direct metal laser sintering process which enables us to make complex three dimensional parts directly from CAD models. Due to layer by layer formation, parts built in this process tend to be anisotropic in nature. Suitable heat treatment can reduce this anisotropic behaviour by changing the microstructure. Depending upon the applications, a wide range of mechanical properties can be achieved between 482–621° C temperature for precipitation-hardened stainless steels. In the present study effect of different heat treatment processes, namely solution annealing, ageing and overaging, on tensile strength, hardness and wear properties has been studied in detail. Suitable metallurgical and mechanical characterization techniques have been applied wherever required, to support the experimental observations. Results show H900 condition gives highest yield strength and lowest tensile strain at break whereas solution annealing gives lowest yield strength and as-built condition gives highest tensile strain at break. SEM images show that H900 and H1150 condition produces brittle and ductile morphology respectively which in turn gives highest and lowest hardness value respectively.XRD analysis shows presence of austenite phases which can increase hardness at the cost of ductility. Average wear loss for H900 condition is highest whereas it is lowest for solution annealed condition. Further optical and SEM images have been taken to understand the basic wear mechanism involved.

Effect of Different Heat Treatments on Mechanical Properties of Laser Sintered Additive Manufactured Parts

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Sagar Sarkar ◽  
Cheruvu Siva Kumar ◽  
Ashish Kumar Nath
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Yield Strength ◽  
Computer Aided Design ◽  
Tensile Strain ◽  
Wear Loss ◽  
Layer By Layer ◽  
Solution Annealing ◽  
Sem Images ◽  
Wide Range

One of the most popular additive manufacturing processes is laser-based direct metal laser sintering (DMLS) process, which enables us to make complex three-dimensional (3D) parts directly from computer-aided design models. Due to layer-by-layer formation, parts built in this process tend to be anisotropic in nature. Suitable heat treatment can reduce this anisotropic behavior by changing the microstructure. Depending upon the applications, a wide range of mechanical properties can be achieved between 482 °C and 621 °C temperature for precipitation-hardened stainless steels. In the present study, effect of different heat treatment processes, namely solution annealing, aging, and overaging, on tensile strength, hardness, and wear properties has been studied in detail. Suitable metallurgical and mechanical characterization techniques have been applied wherever required, to support the experimental observations. Results show H900 condition gives highest yield strength and lowest tensile strain at break, whereas solution annealing gives lowest yield strength and as-built condition gives highest tensile strain at break. Scanning electron microscope (SEM) images show that H900 and H1150 condition produces brittle and ductile morphology, respectively, which in turn gives highest and lowest hardness value, respectively. X-ray diffraction (XRD) analysis shows presence of austenite phases, which can increase ductility at the cost of hardness. Average wear loss for H900 condition is highest, whereas it is lowest for solution annealed condition. Further optical and SEM images have been taken to understand the basic wear mechanism involved.

scholarly journals Microstructure Evolution and Mechanical Properties of X6CrNiMoVNb11-2 Stainless Steel after Heat Treatment

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5243
Author(s):  
Jia Fu ◽  
Chaoqi Xia
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stainless Steel ◽  
Impact Toughness ◽  
Martensite Phase ◽  
High Density ◽  
Air Cooling ◽  
Rocket Engines ◽  
Forming Process ◽  
The Impact

X6CrNiMoVNb11-2 supermartensitic stainless steel, a special type of stainless steel, is commonly used in the production of gas turbine discs in liquid rocket engines and compressor disks in aero engines. By optimizing the parameters of the heat-treatment process, its mechanical properties are specially adjusted to meet the performance requirement in that particular practical application during the advanced composite casting-rolling forming process. The relationship between the microstructure and mechanical properties after quenching from 1040 °C and tempering at 300–670 °C was studied, where the yield strength, tensile strength, elongation and impact toughness under different cooling conditions are obtained by means of mechanical property tests. A certain amount of high-density nanophase precipitation is found in the martensite phase transformation through the heat treatment involved in the quenching and tempering processes, where M23C6 carbides are dispersed in lamellar martensite, with the close-packed Ni3Mo and Ni3Nb phases of high-density co-lattice nanocrystalline precipitation created during the tempering process. The ideal process parameters are to quench at 1040 °C in an oil-cooling medium and to temper at 650 °C by air-cooling; final hardness is averaged about 313 HV, with an elongation of 17.9%, the cross-area reduction ratio is 52%, and the impact toughness is about 65 J, respectively. Moreover, the tempered hardness equation, considering various tempering temperatures, is precisely fitted. This investigation helps us to better understand the strengthening mechanism and performance controlling scheme of martensite stainless steel during the cast-rolling forming process in future applications.

Effect of Heat Treatment on Corrosion Properties of Selective Laser Melted Stainless Steel Parts

2018 ◽  
Author(s):  
Sagar Sarkar ◽  
Saumya Ranjan Jha ◽  
Ashish Kumar Nath
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Metal Powders ◽  
Solution Annealing ◽  
Corrosion Properties ◽  
Pitting Potential ◽  
Suitable Heat Treatment ◽  
Inhomogeneous Microstructure ◽  
Over Time

One of the most popular additive manufacturing processes among today’s manufacturing industries is Selective Laser Melting (SLM) in which very intricate shapes can be fabricated directly from its three dimensional digital design data by melting metal powders using laser. Layer by layer deposition of material about different build axes make SLM parts anisotropic in nature. Also, non-uniformity in thermal loading at top and bottom surfaces of a SLM part leads to inhomogeneous microstructure and may change electro-chemical properties across the part. Suitable heat treatment as a post processing technique can reduce this anisotropy and produce homogeneous microstructure leading to reproducible mechanical and electrochemical properties. Depending upon the application in actual industrial scenarios, SLM parts may be subjected to corrosive media and thus may affect service life of the part. In the present study, effect of different heat treatment namely solution annealing, ageing, overaging on corrosion properties of SLM 15-5 Precipitation-Hardened (PH) stainless steel have been studied. Various metallurgical characterizations have been carried out wherever required to support experimental observations. As-built specimens have approximately six times higher pitting potential which may be attributed to higher nitrogen content present in as-built specimens but corrode more over time than solution annealed (SA) specimens. Relatively bigger size pits and non-uniformity in their distributions can be attributed to residual stresses and inhomogeneous microstructure associated with as-built SLM specimens respectively. Specimen undergone standard ageing condition (H900) corrodes least over time among all the heat treatment conditions considered in the present study. However, in this case, a large number of shallow pits can be observed from the corroded surface. Overaged (H1150) specimens corrode more than H900 specimens but pitting starts late in case of H1150 specimens since pitting potential is almost ten times higher in the former case. Increased ageing temperature and soaking time (Mod H900 (SA)) increases formation of higher Cr23C6 precipitates than that of H900 condition and hence corrode more over time. Ageing without solution annealing (Mod H900 (AB)) leads to higher corrosion and larger pit size non-uniformly distributed over the corroded surface than that of Mod H900 (SA) condition which may be attributed to presence of residual stresses and non-uniform precipitation throughout the matrix. Present study will be useful for selecting suitable heat treatment yielding desired corrosion resistance for SLM stainless steel parts.

scholarly journals Effect of Intercritical Annealing on the Microstructure and Mechanical Properties of 0.1C-13Cr-3Ni Martensitic Stainless Steel

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 392
Author(s):  
Jaka Burja ◽  
Blaž Šuler ◽  
Marko Češnjaj ◽  
Aleš Nagode
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stainless Steel ◽  
Impact Toughness ◽  
Martensitic Stainless Steel ◽  
Large Deviation ◽  
Intercritical Annealing ◽  
Charpy Impact ◽  
Charpy Impact Toughness ◽  
Microstructure And Mechanical Properties

Standard heat treatment of martensitic stainless steel consists of quenching and tempering. However, this results in high strength and hardness, while Charpy impact toughness shows lower values and a large deviation in its values. Therefore, a modified heat treatment of 0.1C-13Cr-3Ni martensitic stainless steel (PK993/1CH13N3) with intercritical annealing between Ac1 and Ac3 was introduced before tempering to study its effect on the microstructure and mechanical properties (yield strength, tensile strength, hardness and Charpy impact toughness). The temperatures of intercritical annealing were 740, 760, 780 and 800 °C. ThermoCalc was used for thermodynamic calculations. Microstructure characterization was performed on an optical and scanning electron microscope, while XRD was used for the determination of retained austenite. Results show that intercritical annealing improves impact toughness and lowers deviation of its values. This can be attributed to the dissolution of the thin carbide film along prior austenite grain boundaries and prevention of its re-occurrence during tempering. On the other hand, lower carbon concentration in martensite that was quenching from the intercritical region resulted in lower strength and hardness. Intercritical annealing refines the martensitic microstructure creating a lamellar morphology.

Mechanical Properties and Microstructure of Aluminum Alloy Al-6061 Obtained by the Liquid Forging Process

2010 ◽  
Vol 654-656 ◽  
pp. 1420-1423 ◽  
Author(s):  
Chun Wei Su ◽  
Peng Hooi Oon ◽  
Y.H. Bai ◽  
Anders W.E. Jarfors
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
Treatment Process ◽  
Forging Process ◽  
Al 6061 ◽  
Casting Alloys ◽  
Suitable Heat Treatment ◽  
Structural Applications ◽  
Wrought Aluminum

The liquid forging process has the flexibilities of casting in forming intricate profiles and features while imparting the liquid forged components with superior mechanical strength compared to similar components obtained via casting. Additionally, liquid forging requires significantly lower machine loads compared to solid forming processes. Currently, components that are formed by liquid forging are usually casting alloys of aluminum. This paper investigates the suitability of liquid forging a wrought aluminum alloy Al-6061 and the mechanical properties after forming. The proper handling of the Al-6061 alloy in its molten state is important in minimizing oxidation of its alloying elements. By maintaining the correct alloying composition of Al-6061 after liquid forging, these Al-6061 samples can subsequently undergo a suitable heat treatment process to significantly improve their yield strengths. Results show that the yield strengths of these liquid forged Al-6061 samples can be increased from about 90MPa, when they are in the as-liquid forged state, to about 275MPa after heat treatment. This improved yield strength is comparable to that of Al-6061 samples obtained by solid forming processes. As such, the liquid forging process here has been shown to be capable of forming wrought aluminum alloy components that has the potential for structural applications.

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