What are the testing methods for the mechanical properties of spiral welded steel pipes

Mechanical property testing methods are mainly divided into two categories: tensile testing and hardness testing.

1. Tensile testing involves preparing a sample from the spiral welded steel pipe and stretching it to fracture on a tensile testing machine. One or more mechanical properties are then measured, typically only the tensile strength, yield strength, elongation after fracture, and reduction of area. Tensile testing of spiral welded steel pipes is a fundamental mechanical property testing method for metallic materials. Almost all metallic materials with mechanical property requirements are subject to tensile testing. Especially for materials whose shape is inconvenient for hardness testing, tensile testing becomes the only means of mechanical property testing.

2. Hardness testing involves slowly pressing a hard indenter into the sample surface under specified conditions, then measuring the indentation depth or size to determine the material's hardness. Hardness testing of spiral welded steel pipes is a relatively simple, rapid, and easy-to-implement method among material mechanical property tests. Hardness testing of spiral welded steel pipes is non-destructive, and there is an approximate conversion relationship between the material's hardness value and tensile strength value. The hardness value of spiral welded steel pipe material can be converted into a tensile strength value, which has great practical significance and is currently a commonly used method.

Comparing the two methods, tensile testing is inconvenient, while converting hardness to strength is very convenient. Therefore, people are increasingly testing only the hardness of materials and less frequently testing their strength. Especially due to the continuous advancement and innovation in hardness tester manufacturing technology, some materials that were previously impossible to test directly in terms of hardness, such as spiral welded steel pipe, stainless steel plate, and stainless steel strip, can now be directly tested for hardness. Therefore, there is a trend of hardness testing gradually replacing tensile testing.