What Are Titanium Alloys?

For purposes of this chapter titanium alloys are those alloys of about 50% or higher titanium that offer exceptional strength-to-density benefits plus corrosion properties comparable to the excellent corrosion resistance of pure titanium. The range of operation is from cryogenic temperatures to around 538–595 C (1000–1100 F). Titanium alloys based on intermetallics such as gamma titanium aluminide (TiAl intermetallic compound which has been designated ) are included in this discussion. These alloys are meant to compete with superalloys at the lower end of superalloy temperature capability, perhaps up to 700 C ( 1300 F). They may offer some mechanical advantages for now but often represent an economic debit. Limited experience is available with the titanium aluminides. Temperature Capability of Titanium Alloys Although the melting point of titanium is in excess of 1660 C (3000 F), commercial alloys operate at substantially lower temperatures. It is not possible to create titanium alloys that operate close to their melting temperatures. Attainable strengths, crystallographic phase transformations, and environmental interaction considerations cause restrictions. Thus, while titanium and its alloys have melting points higher than those of steels, their maximum upper useful temperatures for structural applications generally range from as low as 427 C (800 F) to the region of about 538–595 C (1000–1100 F) dependent on composition. As noted, titanium aluminide alloys show promise for applications at higher temperatures, perhaps up to 700 C ( 1300 F), although at one time they were expected to offer benefits to higher temperatures. Actual application temperatures will vary with individual alloy composition. Since application temperatures are much below the melting points, incipient melting is not a factor in titanium alloy application. 

SELECTION OF TITANIUM ALLOYS

FOR DESIGN

Matthew J. Donachie

Rensselaer at Hartford

Hartford, Connecticut

Mechanical Engineers’ Handbook: Materials and Mechanical Design, Volume 1, Third Edition.

Edited by Myer Kutz

by John Wiley & Sons, Inc.


 

Nuts, bolts, screws and washers

ISO metric precision hexagon bolts, screws and nuts are covered by BS 3643 and ISO 272. The standard includes washer faced hexagon head bolts and full bearing head bolts. In both cases there is a small radius under the bolthead which would not normally be shown on drawings, due to its size, but is included here for completeness of the text. With an M36 bolt, the radius is only 1.7 mm. Bolts may be chamfered at 45° at the end of the shank, or radiused. The rounded end has a radius of approximately one and one quarter times the shank diameter and can also be used if required to draw the rolled thread end. The washer face under the head is also very thin and for a M36 bolt is only 0.5 mm. Figure 16.1(a) shows the bolt proportions and Table 16.1 the dimensions for bolts in common use. Dimensions of suitable nuts are also given and illustrated in Fig. 16.1(b). Included in Table 16.1 and shown in Fig. 16.1(c) are typical washers to suit the above bolts and nuts and these are covered by BS 4320. Standard washers are available in two different thicknesses, in steel or brass, and are normally plain, but may be chamfered. Table 16.1 gives dimensions of commonly used bolts, nuts and washers so that these can be used easily on assembly drawings. For some dimensions maximum and minimum values appear in the standards and we have taken an average figure rounded up to the nearest 0.5 mm and this will be found satisfactory for normal drawing purposes. Reference should be made to the relevant standards quoted for exact dimensions if required in design and manufacture. 

Manual of

Engineering Drawing

Second edition

Colin H Simmons

I.Eng, FIED, Mem ASME.

Engineering Standards Consultant

Member of BS. & ISO Committees dealing with

Technical Product Documentation specifications

Formerly Standards Engineer, Lucas CAV.

Dennis E Maguire

CEng. MIMechE, Mem ASME, R.Eng.Des, MIED

Design Consultant

Formerly Senior Lecturer, Mechanical and

Production Engineering Department, Southall College

of Technology

City & Guilds International Chief Examiner in

Engineering Drawing
 

Geometric Tolerancing

Geometric Tolerancing is used to specify the shape of features.

Things like:

•Straightness

•Flatness

•Circularity

•Cylindricity

•Angularity

•Profiles

•Perpendicularity

•Parallelism

•Concentricity

•And More...

Geometric Tolerances are shown on a drawing with a feature control frame.

The Feature Control Frame

This feature control frame is read as: “The specified feature must lie perpendicular within a

tolerance zone of 0.05 diameter at the maximum material condition, with respect to datum

axis C. In other words, this places a limit on the amount of variation in perpendicularity

between the feature axis and the datum axis. In a drawing, this feature control frame would

accompany dimensional tolerances that control the feature size and position.

Principles of Engineering Drawing

Thayer Machine Shop

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SECTION 3 SURFACE TEXTURE

3.1 SCOPE OF SECTION This Section provides information on the indication of surface texture on

mechanical engineeringdrawingsandsimilar applications.For a more complete understandingof surface

texture, reference should be made to AS 2536.

3.2 SYMBOLS

3.2.1 Basic symbol The basic symbol is shown in Figure 3.1. The dimensions of surface texture

symbols are shown in Figure 3.2. Sloping lines in the symbol are at 60° to the horizontal.

3.2.2 Modification to basic symbol The following modifications may be made to the basic symbol:

(a) The symbol to be used where machining is mandatory shall be the basic symbol with a bar

added, as shown in Figure 3.3.

This symbol may be used alone to indicate that a surface is to be machined without defining

either the surface texture or the process to be used.

(b) The symbol to be used when the removal of material is not permitted shall be the basic symbol

with a circle added, as shown in Figure 3.4. This symbol may be used alone to indicate that a

surface is to be left in the state resulting from a preceding manufacturing process.

3.2.3 Extension of symbols When special surface characteristics are to be indicated (see Clause

3.4), the symbols shown in Figures 3.1, 3.3 and 3.4 may be extended by adding a line of appropriate

length to the long leg, as shown in Figure 3.5.

Australian Standard

Technical drawing

Part 201: Mechanical engineering drawing

Accessed by WOODSIDE ENERGY LTD on 21 Nov 2001

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