Volume 01 - Properties and Selection Irons, Steels, and High-Performance Alloys Part 9 pptx

Hardenability Curves for Nickel-Chromium-Molybdenum 43xx Alloy Steels Figure 35... Hardenability Curves for Nickel-Molybdenum 46xx Alloy Steels Figure 38... Hardenability Curves for Nick

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Hardenability Curves for Nickel-Chromium-Molybdenum (43xx) Alloy Steels

Figure 35 SAE/AISI 4320H UNS H43200 Heat-treating temperatures recommended by SAE Normalize (for forged or rolled specimens only): 925 °C (1700 °F) Austenitize: 925 °C (1700

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Figure 37 SAE/AISI E4340H UNS H43406 Heat-treating temperatures recommended by SAE Normalize (for forged or rolled specimens only): 870 °C (1600 °F) Austenitize: 845 °C (1550

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Hardenability Curves for Nickel-Molybdenum (46xx) Alloy Steels

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Hardenability Curves for Nickel-Molybdenum (48xx) Alloy Steels

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Hardenability Curves for Chromium (50xx) Alloy Steels

Figure 45 SAE/AISI 50B40H UNS H50401 Heat-treating temperatures recommended by SAE Normalize (for forged or rolled specimens only): 870 °C (1600 °F) Austenitize: 845 °C (1550

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Hardenability Curves for Chromium (51xx) Alloy Steels

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Hardenability Curves for Chromium-Vanadium (61xx) Alloy Steels

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Hardenability Curves for Silicon-Manganese (92xx) Alloy Steels

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Sheet Formability of Steels

Revised by W.G Granzow, Armco, Inc., Research & Technology

Introduction

STEEL SHEET is widely used for industrial and consumer products, partly because it is relatively strong, easily joined, and readily available at moderate cost However, it is not these factors, but the formability of steel sheets that is primarily responsible for its wide use The term formability is commonly used to described the ability of a steel to maintain its structural integrity while being plastically deformed into various shapes However, not all shapes require the same forming characteristics, and a steel that has excellent formability in one application may exhibit poor formability in another application In practice, therefore, formability must be optimized by selecting a grade of steel that has the forming characteristics needed to make the required shape

These forming characteristics are normally estimated from an analysis of the mechanical properties of steel, which are determined by uniaxial tensile tests Although this type of test does not simulate any commercial forming operations, the test results have been universally used for many years to evaluate formability, and some understanding of them is

essential to the understanding of sheet steel formability Sheet metal forming methods are described in detail in Forming

and Forging, Volume 14 of ASM Handbook

Examples of formed parts that require different forming characteristics in the steel are shown in Fig 1 Part A was formed

by drawing; that is, all the metal that was required to form the part from a flat blank came from the flanges This shape

requires that the steel have a high plastic-strain ratio, or r value, which determines the resistance of steel sheet to thinning

during forming operations Part C was formed by stretching; the flange on the blank was clamped during forming, and all

of the metal that was required to form the part came from reducing the thickness of the metal This type of part requires

good ductility in the steel However, the r value should be low, because high r values can cause failures of stretched parts

Part B has failed in plane strain, which is a type of stretching Parts that develop this strain condition, such as automotive panels, require good ductility

Fig 1 Parts that required different forming characteristics in the steel sheet

This article discusses the mechanical properties and formability of steel sheet, the use of circle grid analysis to identify the properties of complicated shapes, and various simulative forming tests It covers the effects of steel composition, steelmaking practices, and metallic coatings, as well as the correlation between microstructure and formability A guide to the selection of steel sheet is also included

Sheet Formability of Steels

Revised by W.G Granzow, Armco, Inc., Research & Technology

Mechanical Properties and Formability

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The mechanical properties of steel sheet that influence its forming characteristics, either directly or indirectly, can be measured by uniaxial tension testing, such as that described in ASTM E 8 The tensile test results of particular interest include the yield strength, ultimate tensile strength, total elongation, uniform elongation, yield point elongation, plastic-strain ratio, planar anisotropy, and the strain-hardening exponent Uniaxial tensile tests may be made with specimens obtained from longitudinal, diagonal, transverse, or other orientations relative to the rolling direction Typical mechanical properties for common grades of hot-rolled and cold-rolled steel sheets are given in Tables 1 and 2

Table 1 Typical mechanical properties of hot-rolled steel sheet

Yield strength

Tensile strength Type or quality Special feature

MPa ksi MPa ksi

Elongation in

50

mm (2 in.), %

Hardness, HRB

hardening

Strain-exponent, n

strain

Table 2 Typical mechanical properties of cold-rolled steel sheet

Yield strength

Tensile strength Type or quality Special feature

MPa ksi MPa ksi

hardening

Strain-exponent, n

strain

Tiêu đề	Volume 01 - Properties and Selection Irons, Steels, and High-Performance Alloys Part 9
Trường học	Unknown University
Chuyên ngành	Materials Science and Engineering
Thể loại	lecture presentation
Năm xuất bản	Unknown
Thành phố	Unknown City

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Số trang	160
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