The Impact of New Aerospace Materials, Manufacturing Strategies and

Production Schedules on Machining Techniques and Control

SAE Webcast June 4, 2008

Carpenter Technology Corporation participated in a webinar delivered by SAE International’s Aerospace Engineering & Manufacturing magazine.

Carpenter’s manager of the Forged Bar and Billet Business Group presented a comparison of three major iron- and nickel-base alloy systems used in aerospace applications: stainless steels, high strength-high toughness alloys, and high temperature alloys.  Tips were offered to help improve machining productivity of the non-stainless materials.

Copyright 2008 CRS Holdings, Inc.

Carpenter Produces Vacuum Melted and/or Remelted Aerospace Alloys

in Three Categories

1. High strength/high toughness steels – found in turbine shafts and structural components

2. Martensitic precipitation hardenable stainless steels - structural components and turbine compressor assemblies

3. Nickel-base superalloys - engine compressor and turbine sections

The information and data presented herein are typical or average values and are not a guarantee of maximum or minimum values. Applications specifically suggested for material described herein are made solely for the purpose of illustration to enable the reader to make his/her own evaluation and are not intended as warranties, either express or implied, of fitness for these or other purposes.

Examples of Two Aerospace High Strength/High Toughness Steels

AerMet® 100 Alloy

– Annealed Hardness RC38

– Aged Hardness RC54

– Toughness 110 ksi√in Maraging 250

– Annealed Hardness RC32

– Aged Hardness RC52

– Toughness 75 ksi√in

Increased hardness and toughness demand rigid machining setups and advanced tooling.

Registered trademarks are property of CRS Holdings, Inc., a subsidiary of Carpenter Technology Corporation.

Examples of Aerospace Stainless Steels

Relative strength and toughness of PH stainless steels

720718

31VNi-30

TEMPERATURE

TE

NS

ILE

YIE

LD

ST

RE

NG

TH

Wasp/901/Thermo-Span

X-750

80A/A-286X-750

41909706

75131V

Ni-30/80A/A-286

X-750

720

71841

909/706Thermo-Span

Wasp/901751/X-750

80AA-286X-750

75131V

Ni-30

706Waspaloy

901

720

41718

720

41

720

41Waspaloy

31V/751

Waspaloy

41

720

Waspaloy

Ni-3080A

751901/31V

75°F(24°C)

1500°F(815°C)

1200°F(650°C)

1300°F(705°C)

1400°F(760°C)

1600°F(870°C)

Age-Hardenable Superalloy Selectaloy Diagram (Yield Strength)Age-Hardenable Superalloy Selectaloy Diagram (Yield Strength)

Examples of Nickel-Base Superalloys

Characteristics of Machinability

Productivity

Tool life

Chip size/removal

Surface roughness

Cycle time

Consistency

Material Characteristics Affecting Machinability

High tensile strengths Large spreads between yield and tensile

strengths High ductility and toughness High work hardening rates Low thermal conductivity

Metallurgical properties responsible formachinability characteristics:

Difficulties Associated With Modern Aerospace Materials

Operating conditions in engines and aerospace structures demand higher strength, higher toughness and higher operating temperatures to improve aircraft efficiency.

The higher alloy content required to achieve these properties and the properties themselves lead to lower machining productivity, shorter tool life and more difficult chip formation and removal.

Effect of Thermal Conductivity

Temperature(F)

15Cr-5Ni PH Speed 400 SFM Feed 0.005 IPR

Project 70+® 15Cr-5Ni Speed 400 SFM Feed 0.005 IPR

Temperature(F)

Effect of Thermal Conductivity

Free Machining Additives in Stainless Steels

Type 303 - 200X Magnification

Effect and Limitations of Sulfur Additions

Tool Design Optimization

Project 70+® Type 303 chips vs. back rake angle 0.062” wide cut-off 180 SFPM,0.001 IPR

Angle - 4 degrees

12 degrees

8 degrees

14 degrees

Impact of Tool Design

Data on Speeds, Feeds and Tool Materials

Visit Carpenter’s Technical Information Database at www.cartech.com

Summary:

Materials are typically selected for their properties rather than their machinability.

Sulfurized alloys machine more economically but are limited to specific grades such as 17-4 and 15-5 stainless.

Wise tooling selection and setup, including tool angle and speed, are the keys to maximizing productivity.

Refer to the searchable technical information database at www.cartech.com for suggested speeds and feeds on more than 100 stainless steels and specialty alloys.

Modern Iron and Nickel Base Aerospace Alloys and Their Impact on Machinability

Thank you for your interest in machinability of alloys in the aerospace industry. More information is available on this site, including product literature, alloy datasheets, and technical articles.

To contact Carpenter, call 1-800-654-6543 in the U.S. or refer to the Contact Us page for the location nearest you.