美国FORGE计划犹他州干热岩开发示范项目进展综述

21世纪是全球能源获取方式发生重要变化的时代。现有以煤炭、石油、天然气等传统资源为基础的能源正在逐渐被风能、太阳能、生物质能、地热能等环境友好、低排放的绿色能源所取代。干热岩是一种不含原生水(或含少量水但不能流动)的高温地热资源,可通过水力刺激改造形成增强型地热系统储层,从而提取数量相当可观的地热能。本文以美国能源部正在组织实施的FORGE计划犹他州干热岩示范项目为研究对象,综述了项目在场地地质条件表征、基础设施建设等方面取得的主要进展与成果,总结了项目在高温硬岩钻井、储层建造、微震监测等方面取得的广泛且深入认识,从统筹部署、组织实施、场地表征和设施建设、关键技术装备突破、数据共享等方面提出了值得我国借鉴参考的具体实践。

Effect of nitrogen content on the microstructure and mechanical properties of titanium-bearing nonquenched and tempered steel after hot forging

The microstructure and mechanical properties of titanium(Ti)-bearing medium-carbon nonquenched and tempered steel with different nitrogen content before and after hot forging were investigated through smelting,forging,and laboratory tests.The results show that the grain size of nonquenched and tempered steel was gradually refined,and the ferrite content gradually increased with an increase in nitrogen content.The grain size of the material with low nitrogen content increased abnormally,and its impact properties significantly decreased after hot forging.The grain size of nonquenched and tempered steel with higher nitrogen content was slightly larger than that before forging,and the tensile and yield strength increased,but the impact toughness was not significantly reduced.The Ti-bearing nonquenched and tempered steel showed better strength and toughness after hot forging with the addition of 0.010%0.015%nitrogen.

Simulation-Based Investigation of Crack Formation in Forged MB15 Magnesium Alloy

In the process of riveting an MB15 forging die,cracks were discovered emerging along the longitudinal direction and near the riveting hole.Through fracture analysis,microscopic observation,energy spectrum analysis,metallographic examination,and hardness test,the properties and causes of the cracks are discussed.The results indicate that the cracking type is intergranular brittle cracking,occurring during the forging stage.Furthermore,the recrystallization at the crack site is found to be incomplete,which is attributed to the low deformation temperature.

基于Simufact Forging高铁轮毂锻压成形工艺仿真

基于Simufact Forging有限元分析软件对高铁轮毂成形过程进行了仿真,着重研究了轮毂辗扩过程中的等效塑性应变、等效应力及材料流动。结果表明:高铁轮毂在辗扩过程中材料整体变形基本一致,可以获得较好的力学性能;随着锻压成形不断的进行,轮毂内圈塑性应变逐渐变大;成形过程中整个轮毂应力分布较为均匀。

MICROSTRUCTURAL MODEL OF GATORIZED WASPALOY IN THE ISOTHERMAL FORGING PROCESS

A microstructural model, which was used to predict the evolution of microstructure of Gatorized Waspaloy in the isothermal forging process, was developed in terms of dynamic recrystallization and grain growth. The following three steps of experiment were conducted during developing the model. (1) Specimens were compressed in the MTS testing machine. (2) Dynamic recrystallization and grain growth were discussed. (3) Dynamic recrystallization model and grain growth model were set up. The simulated results are in good agreement with the experimental data.

RIGID-PLASTIC MECHANICAL MODEL FOR THE FORGING METHOD WITH HORIZONTAL V-SHAPED ANVIL

In order to decrease the anisotropy of mechanical properties, the rigid-plastic mechanical model for the forging method with horizontal V-shaped anvil is presented. The forging method, through the change of anvils shape, is able to control fibrous tissue direction, to improve the anisotropy of mechanical properties of axial forgings, to realize uniform forging. Therefore, the forging method can overcome the defect that conventional forging methods produce. The mechanism of the forging method with horizontal V-shaped anvil and the process of metal deformation are analyzed. The agreement of theoretical analysis with experimental study verifies the fact that the forging method with horizontal V-shaped anvil can control effectively the mechanical properties of axial forgings.

Sensitivity Analysis Based Multiple Objective Preform Die Shape Optimal Design in Metal Forging

The multiple objective preform design optimization was put forward. The final forging＇s shape and deformation uniformity were considered in the multiple objective. The objective is to optimize the shape and the deformation uniformity of the final forging at the same time so that a more high integrate quality of the final forging can be obtained. The total objective was assembled by the shape and uniformity objective using the weight adding method. The preform die shape is presented by cubic B-spline curves. The control points of B-spline curves are used as the design variables. The forms of the total objective function, shape and uniformity sub-objective function are given. The sensitivities of the total objective function and the sub-objective functions with respect to the design variables are developed. Using this method, the preform die shape of an H-shaped forging process is optimally designed. The optimization results are very satisfactory.

MODELING OF MICROSTRUCTURAL EVOLUTION IN MICROALLOYED STEEL DURING HOT FORGING PROCESS

The microstractural evolution of microalloyed steel during hot forging process was investigated using physical simulation experiments. The dynamic recrystallized fraction was described by modifying Avrami＇s equation, the parameters of which were determined by single hit compression tests. Double hit compression tests were performed to model the equation describing the static recrystallized fraction, and the obtained predicted values were in good agreement with the measured values. Austenitic grain growth was modeled as： Dinc^5 = D0^5 ＋ 1.6 × 10^32t·exp （ -716870/RT ） using isothermal tests. Furthermore, an equation describing the dynamic recrystallized grain size was given as Ddyn=3771·Z^-0.2. The models of microstructural evolution could be applied to the numerical simulation of hot forging.

Computer Aided Simulation on Precision Cold Forging of Universal Joint Cross

The 3D FEM numerical simulation on multi-action precision cold forging technology of universal joint cross and differential spider is done in this article using DEFORM Software, a commercial computer aided engineering software specializing in forming and heat treatment simulation technology, and suitable for cold, warm and hot forging process. The material flow properties, the dynamic variation of stress and strain in the process of deformation and the load-stroke curve have also been achieved. A good consistency is exhibited between simulation results and practical data. Based on the DEFORM simulation results, the optimized procedure has been found for forging a universal joint cross. What should be emphasized here is that a better understanding of practical forging characters and the environmental factors can greatly improve the simulation accuracy thus make the simulation results more reliable.

Numerical simulation on forging process of TC4 alloy mounting parts

In order to eliminate forging defects appearing in production,based on the rigid-viscoplastic FEM principle,the DEFORM3D software package was employed to simulate the forming process of TC4 alloy mounting part and to optimize the process parameters.In this simulation,the temperature dependency of the thermal and mechanical properties of material was considered.Based on the simulation,the metal flow and thermomechanical field variables such as stress and damage are obtained.The simulation results show that the forging defects are caused by improper die dimension and the optimized die dimension was proposed.To verify the validity of simulation results,forging experiments were also carried out in a forging plant.The forging experiments show that the optimized die dimension can ensure the quality of forging part,and it can provide reference to improve and optimize die design process.

Effect of Zn/Mg/Cu Additions on Hot Cracking Tendency and Performances of Al-Cu-Mg-Zn Alloys for Liquid Forging

During the process of liquid forging, a host of hot cracking defects were found in the Al-CuMg-Zn aluminum alloy. Therefore, mechanical tests and analyses by optical microscope, scanning electron microscope, and X-ray diffraction were performed to research the influences of zinc, magnesium, and copper(three main alloying elements) on hot cracking tendency and mechanical properties. It was concluded that all the three alloying elements exerted different effects on the performances of newly designed alloys. And the impact of microstructures on properties of alloys was stronger than that of solution strengthening. Among new alloys, Al-5 Cu-4.5 Mg-2.5 Zn alloy shows better properties as follows: σb=327 MPa, δ=2.7%, HB=107 N/mm^2, and HCS=40.

Type Design for Heavy-payload Forging Manipulators

Heavy-payload forging manipulators are mainly characterized by large load output and large capacitive-load input.The relationship between outputs and inputs,which will greatly influence the control and the reliability,is the key issue in type design for heavy-payload forging manipulators.In this paper,a type design method by considering the incidence relationship between output characteristics and actuator inputs is presented and used to design the mechanism for forging manipulators.The concept of modeling method based on the outputs tasks is defined and investigated.The principle of type design from the viewpoints of the relationship between output characteristics and actuator inputs is discussed.An idea of establishing the incidence relationship between output characteristics and actuator inputs is proposed.The incidence relationship matrix between outputs and inputs is also given.The design flow is obtained,and the incidence relationship between outputs and inputs for heavy-payload forging manipulators is divided into three parts after detailed understanding of the functional properties.Four types of mechanisms for heavy-payload forging manipulators are given,and the corresponding spatial mechanical sketches are also drawn,some new designed mechanisms have been adopted by company or used as prototype.These novel forging manipulators which satisfy certain functional requirements provide an effective help for the design of forging manipulators and patent application.

Effect of Multiple Forging on Microstructure and Mechanical Properties of Powder Metallurgy FGH4096 Superalloy

FGH4096 is an important damage-tolerance-type powder metallurgy （PM） superalloy, which is also the optimized turbine material for high performance aero-engine. To turbine disc, bore and rim are used in high temperature-low stress condition and low temperature-high stress condition, and dual-microstructure is introduced. Coarse-grained microstructure is suit for rim region and fine-grained is no doubt most suitable for bore region. But fine-grained ingot can not make by PM technique, so that gradient heat treatment can not be developed to coarsen the grain of rim region. Under the confine of PM technique, several treatment processir, g should be taken place to refine the coarse grains of PM alloy. Multiple forging with large accumulate deformation was carried cat on PM FGH4096 superalloy, and fine grains of 3.5 μm were obtained by this treatment processing. Mechanical properties testing were ake carried out on both fine-grained and other statuses alloys, Microstrucmre evolution was observed by optical microscopy, scanning electron microscopy and transmission electron microscopy. As a result of repeated dynamic recrystallizafion, coarse grains could be completely refined into fine grains. And the increase of strength was mainly attributed to refinement effect and improvement of defects such as previous particle boundaries. Successful development of fine-grained treatment processing will promote the research of dual-microstructure turbine disc.

STRESS FIELD ANALYSIS OF EXTRA-HEIGHT FORGING DIE USING FINITE ELEMENT METHOD

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Optimization of TC11 alloy forging parameters using processing maps

Isothermal compression of TC11 alloy at the deformation temperatures ranging from 1023 to 1323 K with an interval of 20 K, the strain rates of 0.001, 0.1, 1.0, and 10.0 s-1, and the height reductions of 50% and 70% was conducted on a Gleeble-1500D thermomechanical simulator. According to the experimental results, the isothermal compression and the processing maps of TC11 alloy at different strains were drawn by using the dynamic material model （DMM）. Based on the processing maps, the proper forging parameters, including a combination of defor-mation temperature and strain rate, vary with the strain in different phases of TC11 alloy.

3D finite element simulation of microstructure evolution in blade forging of Ti-6Al-4V alloy based on the internal state variable models

The physically-based internal state variable （ISV） models were used to describe the changes of dislocation density, grain size, and flow stress in the high temperature deformation of titanium alloys in this study. The constants of the present models could be identified based on experimental results, which were conducted at deformation temperatures ranging from 1093 K to 1303 K, height reductions ranging from 20% to 60%, and the strain rates of 0.001, 0.01, 0.1, 1.0, and 10.0 s-1. The physically-based internal state variable models were implemented into the commercial finite element （FE） code. Then, a three-dimensional （3D） FE simulation system coupling of deformation, heat transfer, and microstructure evolution was developed for the blade forging of Ti-6Al-4V alloy. FE analysis was carried out to simulate the microstructure evolution in the blade forging of Ti-6Al-4V alloy. Finally, the blade forging tests of Ti-6Al-4V alloy were performed to validate the results of FE simulation. According to the tensile tests, it is seen that the mechanical properties, such as tensile strength and elongation, satisfy the application requirements well. The maximum and minimum differences between the calculated and experimental grain size of primary α phase are 11.71% and 4.23%, respectively. Thus, the industrial trials show a good agreement with FE simulation of blade forging.

Impedance Analysis of Forging Process and Strategy Study on Compliance for Forging Manipulator

In the field of heavy forging, there are numerous researches on deformation rule in forging process by FEM simulation, however, not many scholars take the equipment constraint and the mutual reaction load between the forging manipulator clamp and the forging blank into account, which will impact on safety of manipulator body and quality of forging blank. This paper presents an impedance model to describe the load and formulates compliance strategies correspondingly to reduce the mutual reaction load for forging manipulator. Firstly, an FEM model of forging process is built. Meanwhile, the clamp of forging manipulator is added to the model as movement constraint and interaction part between the manipulator and the forming process. Secondly, a typical forging process is simulated by changing the movement constraint, and then an impedance model is established to describe the relationship between the load and movement constraint. Finally, two kinds of compliance strategies are formulated according to the impedance model, one is called free compliance, and the other is initiative/passive compliance. The simulation results show that compliance strategies reduce the load amounting to 5 000 kN in z direction between the manipulator clamp and the forging blank obviously, which may lead to serious accidents, such as the capsizing of forging manipulator, the fracture of manipulator clamp, and so on. The proposed research simulates the more real forging process, gets the initiative/passive compliance strategy which is more simple and suitable to the real producing and better for forming a forging process planning and control system in the modern production, and improves the quality and efficiency of heavy forging.

Filling Rules of Bevel Gears in the Closed-die Cold Forging

The closed-died cold forging technology of the bevel gears used in Jada car was investigated. With the analysis of the strain field and velocity field of the plastic deformation and the endured forces of the dies, the filling rules for the metal were analyzed by the elastic-plastic finite element method （FEM）. The results show that there is a great difference among closed-die cold forging, extrusion and forging, as far as the metal flowing is concerned. The outer addendum cannot be filled completely in the closed-die cold forging of the bevel gears, and the round angle will be formed. But it does not influence the application of the bevel gears. At the beginning, the rigid area is formed in the cavity of the lower die. And then it will move upwards to supply the metal for the gear filling. For the closed-die cold forging of the bevel gears, the force acting on the upper die and the lower die is significantly different.

Preparation of Ni60-WC Coating by Plasma Spraying, Plasma Re-melting and Plasma Spray Welding on Surface of Hot Forging Die

In order to produce the hear-resistant inner layer of hot-forging die, the plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% tungsten carbide （WC） ceramic powder used as coating material to obtain different Nickel-based WC alloys coating. Micro-structure and micro-hardness analysis of the coating layer are conducted, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70%Ni60, 30%WC powder has the best properties with plasma spray welding, in which the micro-hardness can achieve 900HV, meanwhile it can improve the thermal property of hot-forging die dramatically.