Hardness, Rockwell

Hardness, Mohs scale Hardness, Rockwell Hardness, Vickers ... 

Rockwell hardness A Rockwell hardness test Rockwell s hardness Rockwool... 

HRC Rockwell hardness Id less than carload lots... 

Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials Test Method for Vickers Hardness of Metallic Materials Test Method Microhardness of Materials... 

Table 3. Rockwell Hardness Testing Scale Designations...

Recommended Practice for Scleroscope Hardness Testing MetaUic Materials Rockwell Hardness of Bone Cements... 

Most laboratory and shop-use Rockwell hardness testers are nonportable, lever operated, deadweight machines. Newer versions have digital readouts rather than the traditional analogue dial. Some designs of Rockwell testers employ a spring-loading system instead of deadweights. 

Rockwell hardness testing has been extended to both low and high temperature regimes usually by enclosing the sample and part of the machine in an environmental chamber and using extensions for the anvil and indenter. 

Ball- and roller-bearing materials ate commonly selected to provide a minimum Rockwell hardness of 58—60 R at load-carrying contacts (37,38). Below this level, fatigue strength drops so rapidly as to seriously impair the utiUty of a material for rolling beatings which involve contact stresses in the 700—2800 MPa... 

Test Method for Rockwell Hardness of Eine-Grained Graphite Materials... 

Sulfide Stress Cracking) on steels over Rockwell C 22. (4) static stresses. other equipment handling sour gas, oil and/or water wherein H2S and H2O (liquid phase) are present up to about 150 F, where sulfide stress cracking slows down perceptibly. stainless steels with Rockwell hardness over C 22. (4) into crystal structure, exact mechanism uncertain. Sulfur expedites absorption of atomic H into grain structure. (4) if feasible use inhibitors and/or resistant coatings where feasible time or heating up will permit H to diffuse out but will not relieve any areas when H2 has concentrated. 

Hardness. Though carbon is important, it must be used with proper insight to be most effective. In the form of graphite it usually is detrimental. As hard carbides, the form, distribution, and crystallographic character are important. Even hardness must be used with discretion for evaluating wear resistance it should be considered as an unvalidated wear test until its relation to a given service has been proven. Simple and widely used tests (e.g., for Brinell or Rockwell hardness) tell almost nothing about the hardness of microscopic constituents. 

Rockwell hardness — 118R 120R 88M llOM 123R 119R 78M 106M 85M... 

Specific gravity Rockwell hardness Water absorption (24 h)... 

Materials of fabrication again vary with the nature of the gas being compressed but are usually low alloy steel, such as AISI4140 or 4340, heat treated at 1,100°F to Rockwell hardness 26 to 30, AISI Type 410 stainless steel, precipitationhardening stainless such as Armco 17-4PH or 15-5 PH, Type... 

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