Microstructure Evolution and Control of 30Cr2Ni4MoV Steel During Hot Forming

2011 ◽  
Vol 317-319 ◽  
pp. 170-173 ◽  
Author(s):  
Xiao Xun Zhang ◽  
Yun Hua Sun ◽  
Ye Ling Zhu
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Process Parameters ◽  
Microstructure Evolution ◽  
Hot Forming ◽  
Forming Process ◽  
Industry Practice ◽  
Prediction And Control ◽  
3D Software ◽  
And Control

Prediction and control of the microstructure to improve product performance are very important for the industry practice. In this study, microstructure evolutions of 30Cr2Ni4MoV steel under different conditions were simulated by changing the process parameters using the Deform 3D software. Effects of the forming process parameters on the microstructure were revealed: (1) the higher the temperature and the lower the strain rate, the smaller the strain are needed for the dynamic recrystallization; (2) when strain is enough, the higher the strain rate, the easier the uniform and small grain size can be obtained; (3) under a certain strain rate, the grain size increases as the deformation temperature increases. The microstructure of metal can be predicted and controlled according to the effects of hot forming process parameters on the microstructure evolution.

scholarly journals Microstructure Prediction during Incremental Processes for Hot Forming of 718 Alloy

2011 ◽  
Vol 278 ◽  
pp. 186-191 ◽  
Author(s):  
Christian Dumont ◽  
Eric Georges
Keyword(s):  
Grain Size ◽  
Microstructure Evolution ◽  
Phenomenological Approach ◽  
Original Method ◽  
Hot Forming ◽  
Forming Process ◽  
Die Forging ◽  
Microstructure Prediction ◽  
Different Populations ◽  
Additional Assumptions

Main works on microstructure prediction on superalloys during hot forming processes deal with close die forging of 718 alloy. In this paper, we focused our interest towards incremental hot forming process. In that case, matters become more complex, due to the partially recrystallized microstructure we have to take into account at the beginning of each pass. An original method is presented in this paper, still using a phenomenological approach, according to Avrami formulation, with two main additional assumptions, in order to carry out computation on microstructure evolution during the process. Examples with comparisons between real and computed microstructure (recristallyzed fraction, different populations of grain size) enable us to valid our model for bar forging.

Research on Synchronized Cooling Hot Forming Process of 6016 Aluminum Alloy

2012 ◽  
Vol 452-453 ◽  
pp. 81-85 ◽  
Author(s):  
Ming He Chen ◽  
Y.Y. Cao ◽  
W. Chen ◽  
Guo Liang Chen
Keyword(s):  
Aluminum Alloy ◽  
Process Parameters ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Alloy Sheet ◽  
Hot Forming ◽  
Al Alloy ◽  
Forming Process ◽  
Process Step ◽  
6016 Aluminum Alloy

In order to improve formability of high strength Al-alloy sheet metal, in this paper, it come up with the synchronized cooling hot forming process. Taking the aluminum alloy of 6016 H18 aluminum alloy, which carried out its technology test by Gleeble3500 hot-mechanical simulator. The process parameters such as deformation temperature T, holding time t and cooling rate v is investigated by the orthogonal test and the microstructure is analyzed simultaneously. The results show that the synchronized cooling hot forming process can be applied to 6016 H18 aluminum alloy, it both improves the formability of 6016 H18 aluminum alloy significantly and obtains the high strength after forming, it can meet the purpose of implementing deformation and enhanced in one process step, the proper combination of process parameters are T=450 °C, t=210 s, v=60 °C/s. Strengthening mechanism is which there is a large number of strengthening phase precipitated from matrix in technology process, the strengthening phases are coarser and the dispersed uniformity is a bit worse compared with that of T4 state.

Application of a Material Model to Predict Rolling Forces and Microstructure during a Hot Ring Rolling Process

2013 ◽  
Vol 762 ◽  
pp. 354-359 ◽  
Author(s):  
Thomas Henke ◽  
Gerhard Hirt ◽  
Markus Bambach
Keyword(s):  
Grain Size ◽  
Microstructure Evolution ◽  
Rolling Force ◽  
Flow Behavior ◽  
Rolling Process ◽  
Ring Rolling ◽  
Experimental Investigations ◽  
Forming Process ◽  
Ring Geometry ◽  
Ring Rolling Process

Ring rolling is an incremental bulk forming process. Hence, the process consists of a large number of alternating deformations and dwell steps. For accurate calculations of material flow and thus ring geometry and rolling forces in hot ring rolling processes, it seems necessary to consider material softening due to static and post dynamic recrystallization which could occur between two deformation steps. In addition, due to the large number of cycles, the modeling results, especially the prediction of grain size, can easily be affected by uncertainties in the input data. However, for small rings and ring material with slow recrystallization kinetics, the interpass times can be short compared to the softening kinetics and the effect of softening can be so small, that microstructure evolution and the description of the materials flow behavior can be de-coupled. In this paper, a semi-empirical JMAK-based model for a stainless steel (1.4301/ X5CrNi18-9/ AISI304) is presented and evaluated by the use of experiments and other investigations published in [1],[2]. Finite Element (FE) simulations of a ring rolling process with a high number of ring revolutions and thus multiple, incremental forming steps were conducted based on ring rolling experiments. The FE simulation results were validated with the experimentally derived rolling force and evolution of ring diameter. The microstructure evolution was calculated in a post processing step considering the investigated evolution of strain and temperature. In this calculation the interrelations between the fraction of dynamically recrystallized microstructure, the evolution of post-dynamically recrystallized microstructure and the final grain size have been considered. Both, the calculated final microstructure and the evolution of rolling force and ring geometry calculated stand in good agreement with the experimental investigations.

Fabrication of Csf/Mg Composites Using Extrusion Directly Following Vacuum Infiltration - Part 1: Monitoring and Acquiring of Process Parameters

2008 ◽  
Vol 141-143 ◽  
pp. 85-89 ◽  
Author(s):  
Ji Ming Zhou ◽  
Le Hua Qi ◽  
Jun Tao Guan
Keyword(s):  
Data Acquisition ◽  
Process Parameters ◽  
Vacuum Infiltration ◽  
Forming Process ◽  
The Press ◽  
Data Acquisition Card ◽  
User Friendly ◽  
And Control ◽  
Collecting System ◽  
Selection Of

Many process parameters are involved during the fabrication of Csf/Mg composites using extrusion directly following vacuum infiltration. The selection of suitable process parameters is important for the successful fabrication of composites. This will require a continuous monitoring and collecting system of process parameters. This paper describes how this is performed. The monitoring and collecting system is developed to monitor and control the forming process successfully. The hardware was built with data acquisition (DAQ) card based on PCI and various sensors for temperature, pressure, displacement. The industrial computer is used to process the data collected from the sensors. The data acquisition card is the bridge between the computer and sensors. In order to reduce the signal noise from sensors, the hardware filter circuit is designed. The data acquisition card can not work by connecting the computer and sensors through it simply. It must be operated through the self-developed software. The data colletcing software is developed in this paper. It can realize the parameter monitoring and collecting easily by setting up the hardware through the user friendly interface. The curves of parameters can be displayed on the computer screen and the data can be saved into the database for post-processing. The software also supplies the warning function. When the parameters (for example the temperature of mold) arrives the set value, the computer can sound a note of warning to tell the worker to operate the press. It is demonstrated that the main parameters, such as temperature of mold and liquid metal, the loaded pressure and the displacement of punch, can be monitored and collected in real-time by use of this system. This paper found the base for the further selection of optimized process parameters.

Studies on the Hot Forming and Cold-Die Quenching of AA6082 Tailor Welded Blanks

2016 ◽  
Vol 716 ◽  
pp. 941-947
Author(s):  
Jun Liu ◽  
Ai Ling Wang ◽  
Hao Xiang Gao ◽  
Omer El Fakir ◽  
Xi Luan ◽  
...  
Keyword(s):  
Strain Rate ◽  
Strain Path ◽  
Element Model ◽  
Hot Forming ◽  
Forming Limit ◽  
Forming Process ◽  
Tailor Welded Blanks ◽  
Die Quenching ◽  
Experiment And Simulation ◽  
Temperature Strain

An advanced forming process involving hot forming and cold-die quenching, also known as HFQ®, has been employed to form AA6082 tailor welded blanks (TWBs). The HFQ® process combines both forming and heat treatment in a single operation, whereby upon heating the TWB, it is stamped and held between cold tools to quench the component to room temperature. The material therefore undergoes temperature, strain rate or strain path changes during the operation. In this paper, a finite element model (FEM) was developed to investigate the formability and deformation characteristics of the TWBs under HFQ® conditions. Experimental results, i.e. strain distribution, were used to compare and validate the simulation results. A good agreement between the experiment and simulation has been achieved. The developed temperature, strain rate and strain path dependent forming limit prediction model has been implemented into FE simulation to capture the complicated failure features of the HFQ® formed TWBs. It is found from both experiment and simulation that the forming speed has important effects on the occurrence of failure position, where the failure mode for the 1.5-2 mm TWBs may change from localised circumferential necking to parallel weld necking.HFQ® is a registered trademark of Impression Technologies Ltd.

scholarly journals Investigation on precision and performance for hot gas forming of thin-walled components of Ti2AlNb-based alloy

2018 ◽  
Vol 190 ◽  
pp. 07001
Author(s):  
Xueyan Jiao ◽  
Zhiqiang Liu ◽  
Yong Wu ◽  
Gang Liu
Keyword(s):  
Process Parameters ◽  
Microstructure Evolution ◽  
Element Model ◽  
Parameters Optimization ◽  
Forming Process ◽  
Performance Control ◽  
Hot Gas ◽  
Thin Walled ◽  
And Performance ◽  
Hot Gas Forming

Ti2AlNb-based alloys have received considerable attention as potential materials to replace the nickel alloy at 600-750 °C, depending on their advantages of high specific strength, good corrosion and oxidation resistance. To realize the precision and performance control for Ti2AlNb-based alloy thin-walled components, the microstructure evolution was analyzed for setting up the unified viscoplastic constitutive equations based on the physical variables and simulating the forming process coupled between the deformation and the microstructure evolution. Through the finite element model with coupling of microstructure and mechanical parameters, the microstructure evolution and shape fabricating can be predicted at the same time, to provide the basis for the process parameters optimization and performance control. With the reasonable process parameters for hot gas forming of Ti2AlNb thin-walled components, the forming precision and performance can be controlled effectively.

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