Forging Handbook

First page Table of contents Next page Last page

SECTION 1: INTRODUCTION AND APPLICATIONS	XI
Condensed Glossary of Forging Terms	XI
Basic Forging Advantages	6
Directional Strength	6
Structural Integrity	6
Impact Strength	7
Uniformity	7
Metallurgical Spectrum	7
Physical Limits	7
Compatibility	8
Economic Advantages	8
Applications: Past and Present	9
American Axes	9
Hammers	9
Cutlery	9
The Horseless Carriage	10
Major Breakthroughs	10
Current Industry Profile	16
The State of the Industry in the I 980s	16
Forging Industry Concerns: A 20-Year Outlook	16
Conclusion	18
Future Trends	19
Forging Products	19
Materials	21
Productivity	22
Computerization	25
Purchasing of Forgings	26
Types of Forge Plants	27
A Service Industry	27
Inquiries and Orders for Forgings	28
Engineering Consultation	28
Providing Complete Information	28
Checklist for Forging Inquiries and Orders	29
References	30
SECTION 2: FORGING DESIGN	31
Types of Forgings	31
Die Forgings	31
Forging Design Principles and Practices for Aluminum	32
Parting Line	32
Die Side Thrust	33
Intersection of Parting Line and Forging Plane	33
Draft Angles	33
Matching Parting Line Contours	35
Constant Draft Angles for Best Die Economy	35
Undercuts and Back Drafts	35
Finish Allowances for Machining	36
Corner Radii	39
Fillet Radii	43
Grain Flow	44
Flash	45
Webs	45
Die Deflection	47
Pockets and Recesses	47
"Bathtub" Sections	49
Punchouts	50
Pads Added at Parting Line	50
Match Marks and Vent (Knockout) Marks	51
Drafting Conventions for Forgings	51
Engineering Terms	58
Tolerances for Die Forgings	59
Die Closure Tolerances	61
Coining Tolerances	62
Dimensional Tolerances	62
Match Tolerances	63
Straightness Tolerances	63
Flash Extension Tolerances	65
Draft Angle, Angular Radii , and Quantity Tolerances	65
Knockout and Vent Mark Tolerances	65
Additional Tolerances	66
Designs for Shapes Produced on Horizontal Forging Machines (Upsetters)	67
Conventional Forging Design: Other Alloy Systems	67
Parting Line	67
Finish Allowance	67
Draft	68
Corner and Fillet Radii	69
Minimum Section Size/Maximum Rib Height	69
Die Closure/Thickness Tolerances; Length and Width Tolerances	70
Match/Mismatch Tolerances	71
Computer-Aided Design and Manufacturing (CAD/CAM) Applications in Forging	76
Close-Tolerance Forging of Spiral Bevel Gears	78
Design of Finisher Dies	79
Design of Blocker Dies	79
Computer-Aided Simulation of the Forging Process	79
Future Outlook	80
References and Bibliography	81
SECTION 3: MATERIAL CHARACTERISTICS	83
The Metallic Bond and Crystal Structure	83
Plasticity in Metals	85
Deformation Mechanisms at Cold-Working Temperatures	86
Deformation Mechanisms at Warm- and Hot-Working Temperatures	86
Strengthening Mechanisms in Metals	89
Solid-Solution Hardening	89
Second Phase Hardening	89
Strain Aging	89
Hardening by Allotropic Transformation	89
Stability of Strengthening Mechanisms at Elevated Temperatures	90
Forgeability and Workability Tests for Open Die Forging	91
Forgeability of Cast Structures	91
Forgeability of Recrystallized Structures: Hot/Warm-Working Temperature Regime	93
Forgeability Involving Fracture-Controlled Defect Formation	94
Workability Tests for Establishing Effects of Process Variables	94
Tests for Establishing the Effect of Secondary Tensile Stresses on Forgeability	96
Forgeability Involving Flow-Localization-Controlled Failure	98
Forgeability of Recrystallized Structures: Cold-Working Temperature Regime	100
Forgeability and Metal Flow in Closed Die Forging	103
Control of Grain Flow in Closed Die Forging	103
Factors Affecting Die Filling	105
Effect of Metal Flow on Grain Structure Development	109
Metal Flow Defects	110
Empirical Guidelines for Die and Preform Design	111
Physical Modeling	113
Process Modeling	113
Forging Ferrous Alloys	119
Carbon and Alloy Steels	119
Martensitic Stainless Steels	121
Austenitic Stainless Steels	122
Precipitation Hardening Steels	122
Maraging Steels	123
Forging Light Alloys	124
Aluminum and Aluminum Alloys	124
Magnesium Alloys	125
Titanium and Titanium Alloys	125
Types of Titanium Alloys	127
Forging High-Temperature Superalloys	131
Forging Behavior: General Trends	132
Design Considerations for Forged Superalloys	134
Important Processing and Material Variables for Superalloy Forging	135
Effects of Processing on the Microstructure and Properties of Superalloys	137
Forging Refractory Metals	141
Molybdenum and Molybdenum Alloys	141
Columbiurn and Columbium Alloys	141
Tantalum and Tantalum Alloys	142
Tungsten and Tungsten Alloys	142
Beryllium Grades	143
References and Bibliography	145
SECTION 4: MANUFACTURE OF FORGINGS	147
Introduction	147
Preliminary Engineering	147
Stock Preparation	149
Heating for Forging	149
Typical Forging Sequence	150
Heat Treating	152
Cleaning	152
Finishing Operations	153
Inspection	153
Forging Processes and Methods	154
Compression Between Flat Dies	154
Compression Between Narrow Dies	154
Rolling	154
Impression Die Forging	154
Extrusion	156
Piercing	157
Preforming in Forging Practice	157
Ring Rolling	159
Flashless Forging	163
Precision Forging Processes	163
Cold Forging	171
Isothermal and Hot Die Forging	174
Powder Preform Forging	178
Thermomechanical Treatments	179
Upsetting	181
Roll Forging	185
Radial Forging	187
Special Forging Techniques	188
Equipment for Forging	193
Hammers	193
Forging Presses	195
Mechanical Forging Presses	195
Hydraulic Presses	196
Screw Presses	197
Forging Machines (Upsetters)	198
Selection of Forging Equipment	201
Interaction Between Process Requirements and Forging Machines	201
Classification and Characterization of Forging Machines	202
Hydraulic Presses	202
Mechanical Crank and Eccentric Presses	203
Screw Presses	208
Hammers	211
Tool and Die Manufacture	213
Material Considerations	213
Die Steels for Hot Forging	213
Die Materials for Cold Forging	215
Fabrication of Impression Forging Dies	215
Dies for Precision Forging	219
Use of Computerized Systems	220
Lubrication in Forging	223
Conventional Hot Forging	223
Selecting the Proper Lubricant	224
Lubricant Application	224
Isothermal and Hot Die Forging	224
Heat Treatment Practices	226
Heat Treatment of Steel Forgings	226
Heat Treatment of Carbon and Alloy Steels and Martensitic Stainless Steels	227
Cooling Reactions	228
Annealing	230
Normalizing	233
Hardenability	234
Tempering	236
Other Heat Treatment Processes for Hardenable Steels	238
Heat Treatment of Stainless Steels	245
Heating Methods for Ferrous Forgings	245
Computer-Aided Heat Treatment	247
Controlled Cooling of Steel Forgings to Develop High Strength	249
Heat Treatment of Nonferrous Forgings	249
Heat Treatment of Aluminum Alloys	251
Heat Treatment of Superalloys	252
Heat Treatment of Titanium Alloys	253
Controlled Quality Forging	256
Control, Inspection, and Testing of Incoming Stock	256
Process Control	256
Control of Heat Treatment	257
Methods of Validating Forging Integrity	257
Nondestructive Testing	257
Destructive Evaluation	260
Mechanical Property Evaluation	261
Test Material From Forgings	261
Test Specimen Preparation	262
Statistical Testing Methods	262
Principal Mechanical Testing Procedures	262
References	270
GLOSSARY	273
INDEX	287

Made with FlippingBook Digital Proposal Maker