Valve Steel. Valve Steel

Transcription

1 Valve Steel Valve Steel

2 BÖHLER-UDDEHOLM Precision Strip AB is one of the world s leading manufacturers of high quality strip steel. More than a century s experience of cold rolling has given us a unique competence in precision strip steel production. We are specialized in advanced combinations of properties and close tolerances. Management Systems Quality, reliability and service are the keynotes of our operations. Our extensive experience and know-how makes it possible for us to supply a comprehensive array of technical- and customer services. BÖHLER-UDDEHOLM Precision Strip AB is continuously developing new materials and products in close co-operation with the customers involving product engineers and designers in a variety of fields. In addition to printing doctor blade steel and coater blades our product range includes steel for saws, springs, razor blades and scalpels and many other precision strip steel applications in accordance with our customers requirements. BÖHLER-UDDEHOLM Precision Strip AB is represented worldwide. Since 1992 the company is a wholly owned subsidiary of Böhler-Uddeholm AG. Apart from our direct sales we are represented by Böhler-Uddeholm subsidiaries globally. We export about 90% of our production and work closely with our subsidiaries to ensure that we fulfil our customers desires. Valve Steel 2

3 Manufacturing process Throughout the manufacturing process of our valve steels the following objectives are crucial. Selected raw materials and careful metallurgical practice produce a structure without harmful inclusions. The steel grades used facilitate the necessary strength and fatigue properties. Modern compressors require valve components, which have to meet exact demands. BÖHLER-UDDEHOLM Precision Strip AB valve steels offer the necessary base for a successful valve component manufacture. They are specially designed for valve applications and will therefore facilitate a reliable long-term service. Our valve steel technology has undergone an extensive research and development program. This program not only includes materials research but also to a great extent valve application in general. Requirements for valves Valve components are the most severely stressed parts in compressors and need to fulfill special criteria: The design of valve components needs to meet various demands from the compressor maker. The valve steel must allow precision blanking and long tool life. Good sealing between the valve and the valve seat. A steady, long-term performance is essential. A uniform and high strength is achieved through accurate heat treatment. The flatness constitutes a guarantee for perfect valve sealing. Accurate surface finishing eliminates dangerous scratches and stress raisers. Management systems in accordance with: ISO 9001 / TS for quality ISO for environment Applications Valves made from Böhler-Uddeholm Precision Strip are used in compressors for: Refrigerators Air conditioners Freezers Heat pumps Other applications are valves in air- and gas compressors and in two-stroke engines. At the leading edge 3

4 Valve steel characteristics The exacting demands for valve components are constantly kept in mind throughout the manufacture of our valve steels. Despite the fact that flapper valves and other compressor valves represent different requirements, they are both covered by the BÖHLER-UDDEHOLM Precision Strip AB valve steel concept. Selection of steel grades, heat treatment, surface finishing and subsequent operations are carried out with great care and precision. Steel Grades Extensive testing has proven that martensitic hardened and tempered steels constitute the ultimate material characteristics when superior fatigue performance is required. The precision strip steel and its heat treatment provide the prerequisite for a good fatigue performance of the valve. The surface finish and the metallurgical cleanliness secure the required performance. A reliable operation and a long lasting service life of the compressor are the results. However, valve design and manufacture have to be carried out with the same care and accuracy as we treat the strip steel in order to assure satisfying results. To satisfy all our clients requirements our valve steel program comprises martensitic steels in both carbon and stainless grades, which meet the stringent customer demands. UHB 20C is a 1% carbon steel with high tensile strength and is often the standard choice for the medium and thinner range of valve components the flapper valves. It is hardened and tempered to a fine martensitic structure providing the highest fatigue strength among all unalloyed steels. UHB 15N20 is a 0.75% carbon Ni alloyed steel and is ideal for the heavier size range. It has 2% nickel, which assures a homogenous structure of fine-grained martensite through the complete cross section. UHB Stainless 716 is the stainless steel grade designed for the medium and thinner range of valve components where toughness and impact strength are essential. UHB Stainless 716 is also used at elevated working temperatures ( C) and/or in corrosive atmosphere. The 13% chromium steel is delivered in the hardened and tempered condition and has been proven to offer superior bending fatigue and impact fatigue properties. UHB Stainless 731 is used for heavier sizes. It is a 13% chromium steel with a reduced carbon content. This simplifies the blanking of heavier parts. Operation environment and load characteristics must be evaluated before a decision, which steel to use for certain applications, can be taken. The following chart provides you guidance in selecting the steel grade. Valve Steel 4

5 Steel grade selection guide Requirement UHB 20 C Stainless 716 UHB 15N20 Stainless 731 Size 1 mm over 1 mm moderate Fatigue load high moderate Impact load high low Corrosion risk high moderate Flatness after blanking high *) *) Operation temperature 200 C 400 C recommended not recommended *) Photo chemical machining to be considered instead of blanking At the leading edge 5

6 Specification Chemical composition Steel Grade Chemical composition [% nominal] C Si Mn P S Cr Ni Mo UHB 20C UHB 15N Stainless Stainless Physical Properties Steel grade UHB 20 C UHB 15N20 UHB Stainless 716 UHB Stainless 731 Width range Thickness range 340 mm (13.39 ) 1.00 mm (.0394 ) 340 mm (13.39 ) mm ( ) 340 mm (13.39 ) 1.00 mm (.0394 ) 340 mm (13.39 ) mm ( ) Surface finish 0.60 mm (.0236 ) white extra smooth white extra smooth > mm white very smooth white very smooth (> ) white smooth white smooth > mm (> ) white smooth white smooth Edges sheared and deburred Width tolerance B1 B3 B1 B3 B1 B3 B1 B3 Thickness tolerance T2 T4 T1 T4 T1 T4 T1 T4 Flatness group P3 P3 P3 P3 Straightness group R1 R3 R1 R3 R1 R3 R1 R3 Form of supply coils coils or lengths coils coils or lengths Tensile strength see table 1520 ±80 N/mm² ±11600 psi 1810 ±80 N/mm² ±11600 psi 1670 ±80 N/mm² ±11600 psi Valve Steel 6

7 Straighness tolerances Strip width < 8 mm 8 (20) mm 20 (50) mm 50 (125) mm 125 mm Tolerance Measuring length class 1 m 3 m 1 m 3 m 1 m 3 m 1 m 3 m 1 m 3 m Maximum allowed straightness deviation [mm] R R R R R9 As per customer s special requirements Mechanical properties UHB 20C mm Thickness inch N/mm² ± 80 Tensile strength Psi ± (1.15).0354 (.045) (1.50).045 (.059) Flatness (cross camber) Thickness tolerances mm Thickness inch T1 mm (±) Thickness tolerance T2 mm (±) T3 mm (±) (for widths up to 250 mm or 9.84 ) Tolerance class Maximum permitted deviation [% of nominal strip width] P0 Unspecified P1 0.4 P2 0.3 P3 0.2 P4 0.1 P9 as per customer s special requirement At the leading edge 7

8 Copyright BÖHLER-UDDEHOLM Precision Strip AB BÖHLER-UDDEHOLM Precision Strip AB P.O. Box 503 SE Munkfors, Sweden Tel.: Fax: We reserve the right to make alterations without prior notice. BÖHLER-UDDEHOLM Precision Strip AB does not assume liability for any consequence of the use of the steel. The information in this brochure/catalogue is furnished for guidance only and with no guarantees as to its accuracy or completeness.