In today’s fast-paced world, it is critical for manufacturers to have methods and standards available to them to ensure the products they are creating are of the highest quality. This is especially true for manufacturers of finished goods that will be sold directly to consumers. A common way to gauge a material’s hardness is with the Rockwell hardness test. This post references the ASTM Rockwell hardness standard test and will teach you all you need to know.
I. Significance of Rockwell Hardness Standard Test
To correlate the wear and resistance, tensile strength, elasticity, and other physical characteristics of metallic materials, the Rockwell Hardness Test, an empirical hardness test, is used.
Rockwell hardness testers are widely used in the industry and are helpful in the quality control of manufactured goods and commercial shipments.
The general physical characteristics of the finished product are not represented by the Rockwell hardness test on a single part of the product.
II. Principles of Rockwell Hardness Test
There are three main steps involved in the operational principle of the Rockwell hardness test. In the first step, a preliminary force is placed to the indenter for a predetermined dwell duration while in contact with the test sample. The depth of the depression left by the preliminary force is then measured.
Another load is then added to the preliminary load for a specified dwell time in the second step. This load, known as the major load, is an increase in the force acting on the indenter at a controlled rate. This major load causes a deeper indent than the one caused by the preliminary force, and this measurement is taken.
This major load causes a deeper indent than the one caused by the preliminary force, and this measurement is taken.
In the third stage, the additional force (major load) is removed, remaining with the preliminary force. The preliminary force is held for a specified, and the final measurement is taken.
To get the Rockwell hardness value of the test sample, you need to subtract the value of the baseline depth from the final depth measurement obtained after the testing process. Tungsten carbide balls or conical diamond indenters with specified sizes are used to perform the Rockwell hardness test. Steel may be used to perform the test on very thin sheet tin mill products. Steel may be used to perform the test on very thin sheet tin mill products.
III. Surface Preparation
- The test piece should be smooth and clean on both sides for the best results. The test piece should be smooth and clean on both sides for the best results. There shouldn’t be any lubricants or foreign objects on the test piece’s surface. Only reactive metals should be an exception, in which case you should apply a proper lubricant such as kerosene. The test report should specify that a lubricant has been used in the test.
- You should prepare the test piece thoroughly to reduce surface hardness changes that could result from heating or grinding the item.
IV. Verification Testing
You must verify the testing machines at predetermined times and regular intervals. There are three standard processes for verification:
- Direct Verification: This verification is performed when a new machine is purchased or when repairs or adjustments are made that might impact the machine’s ability to withstand test forces, depth-measuring capabilities, or hysteresis.
- Indirect Verification: If necessary, this verification process should occur at least once every year. The time for an indirect verification should not exceed 18 months. Indirect verification can also be performed when a machine is installed or moved to a new location. This is not applicable where the testing machine is designed to move, though.
- Daily Verification: This verification should be carried out every day before a new test is conducted. Daily verification should also be conducted each time an indenter, anvil, or test force is changed.
V. Testing Requirements
- When conducting the Rockwell hardness testing, the temperatures should be kept between 10°C to 30°C. (50° to 95° F). This is because varying temperatures can affect the test results adversely depending on the test sample.
- The test piece should be firmly held to minimize movement during the test cycle.
- To minimize residual lubrication on the sample’s surface, you should ensure that the test piece is properly cleaned and dried after the test.
- You should use stainless steel fixturing for testing. You should also use anvils or blocks of special design and thickness to ensure good contact between the test piece and anvil.
- The Rockwell hardness testing machine should have a double seal system to ensure against leakage from both sides of the machine during a test cycle.
- You should use special consideration when testing materials that exhibit hardness gradients. You should use the relevant Rockwell scale when testing such materials.
VI. ASTM Standards
Test Method and Definitions for Mechanical Testing of Steel Products
Specification for Tin Mill Products, General Requirements
Specification for Tin Mill Products, General Requirements[Metric]
Standard Test Methods for Equotip Hardness of Steel Products
Specification for Cartridge Brass Sheet, Plate, Bar and Disk
Specification for Brass Plate, Sheet, Strip and Rolled Bar
Specification for Copper-Silicon Alloy Plate, Sheet, Strip, and Rolled Bar for General Purposes and Pressure Vessels
Specification for Phosphor Bronze Plate, Sheet, Stipend Rolled Bar
Specification for Leaded Brass Plate, Sheet, Strip and Rolled Bar
Specification for Copper-Nickel-Tin Alloy, Copper-Nickel-Zinc Alloy, and Copper-Nickel Alloy Plate, Sheet, Strip and Rolled Bar
Specification for Commercial Bronze Strip for Bullet Jackets
Specification for Brass Wire
Specification for Copper Sheet, Strip, Plate and Rolled Bar
Standard Test Methods for Hardness of Electrical Contact Materials
Standard Test Methods for Hardness of Cemented Carbides
Specification for Copper Sheet and Strip for Building Construction
Standard Test Methods for the Micro Hardness of Electro-plated Coatings
Standard Test Methods for Indentation Hardness Testing of Aluminum Alloys.
Standard Test Methods for Microhardness and Case Depth of Powder Metallurgy Parts
Standard Test Methods for Indentation Hardness of Aluminum Alloys using a Newage Portable Non-Caliper-type Instrument
Standard Test Methods for Indentation Hardness of Elastomeric-type Sealants by Means of a Durometer
Standard Test Methods for Knoop Indentation Hardness of Glass
Standard Test Methods for Rockwell Hardness of Fine-Grained Graphite Materials
Standard Test Methods for Knoop Indentation Hardness of Ceramic Whitewares
Standard Test Methods for Scleroscope Hardness, Testing of Fine-Grained Carbon and Graphite Materials
Standard Test Methods for Knoop Indentation Hardness of Advanced Ceramics
Standard Test Methods for Vickers Indentation Hardness of Advanced Materials
Standard Test Methods for Rockwell Hardness of Plastic and Electrical Insulating Materials
Standard Test Methods for Rubber Property-International Hardness
Standard Test Methods for Indentation Hardness of Organic Coatings
Standard Test Methods for Rubber Property-Durometer Hardness
Standard Test Methods for Indentation Hardness of Rigid Plastic by Means of a Barcol Impressor
Standard Test Methods for Brinell Hardness of Metallic Materials
Standard Test Methods for Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials
Practise for Using Significant Digits in Test Data to Determine Conformance with Specifications
Standard Test Methods for Vickers Hardness of Metallic Materials
Standard Test Methods for Rapid Indentation Hardness Testing of Metallic Materials
Standard Test Methods for Indentation Hardness of Metallic Materials by Portable Hardness Testers
Standard Test Methods for Hardness Conversion Tables for Metals
Standard Test Methods for Microhardness of Materials
Standard Test Methods for Conducting Interlaboratory Study to Determine the Precision of Test Methods
Standard Test Methods for Macro-Rockwell Hardness Testing of Metallic Materials
Standard Test Methods for Composite Foam Hardness-Durometer Hardness
VI. ISO Standards
Standard Test Methods for Rockwell Hardness of Metallic Materials Part 1: Test Method (Scales A, B, C, D, E, F, G, H, K, N, T)
Standard Test Method for Conformity Assessment and General Requirements for Accreditation Bodies Accrediting Conformity Assessment Bodies
Standard Test Methods for General Requirements for the Competence of Testing and Calibration Laboratories
In addition to hardness testing, you can also use this hardness testing method for structural analysis, material characterization, and engineering property analysis.
You should always adhere to the standard methods and procedures defined in the Standard Test Methods for Rockwell Hardness of Metallic Materials reference. You must use good quality testing machines and equipment during the test. You should always perform the Rockwell hardness test on samples that have been prepared properly. The Rockwell hardness test is a quick and effective way of testing materials with high accuracy and reliability.