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How to Test the Hardness of Stainless Steel

In this blog post, you’ll read:The hardness of the stainless steel is significant to ensure that it can resist the impact of external force and maintain its durability. It is also crucial to know how to test the hardness of stainless steel. Here are the guide for you.

Table of Contents

Experts and materials engineers have often relied on the non-corrosive properties of stainless steel for use in very specific corrosion-prone areas. However, they also know that testing for its hardness is a standard process they must carry out to identify if its tensile strength can withstand the impact of the force it will receive. Thankfully, accurate hardness testing methods are available to determine the hardness value of stainless steel. These hardness tests can conveniently provide the information required by material professionals to determine the suitability of stainless steel material for a specific job. This article will help you understand the workings and procedures of these testing methods.

 

Test the Hardness of Stainless Steel

 

I. What is the Hardness of Stainless Steel?

Stainless steel, like other metals and alloys, is often used in different industries for specific component design and manufacture due to its non-corrosive nature. However, its ability to withstand the impact of forces from other moving components, parts, and environmental forces can significantly impair its efficiency. Hence, ascertaining its hardness value by carrying out hardness testing using some standard hardness testing methods often helps to determine its tensile strength. The hardness value of stainless steel will determine its suitability for an intended design or use. It can also indicate the durability of stainless steel components to overcome abrasion, wear, tear and deformations during use.

 

II. What Determines the Hardness of Stainless Steel?

To be clear, stainless steel is a good anti-corrosive steel alloy with a combination of certain elements and metals in specific quantities based on the targeted property of the final stainless steel. Usually, it contains carbon and chromium in varying percentages depending on the level of anti-corrosion and the hardness level required. It turns out that more carbon reduces its anti-corrosion properties but increases its hardness value, while more chromium reduces its hardness value but increases its anti-corrosion properties. Interestingly, the addition of other elements like Nickel, vanadium, titanium, and aluminum help to increase its hardness and as such, it can resist more impact.

 

III. Hardness Test Methods for Stainless Steel Hardness

Not carrying out hardness tests on stainless steel can often box manufacturers into a tight corner when the material or component eventually fails. To avoid operational failure, material experts and quality assessment professionals turn to some standard hardness testing methods to determine the hardness value of stainless steel material. 

 

  • Rockwell Hardness Test

Considered one of the most popular hardness tests, the Rockwell hardness test utilizes an indenter with a range of loads. These loads combine as a set of two loads where one is smaller and applied first, followed by the second load with a higher value applied next. The difference between the indentation depth caused by the set of two loads gives the Rockwell hardness value. Depending on the sets of two loads employed and the type of indenter, Rockwell can have different scales often designated as A, B, C, D, or E. These alphabets align with the Rockwell hardness value’s general HR designation to identify the different scales.

 

  • Brinell Hardness Test

This hardness test is suitable for ferrous and non-ferrous metals, including hardened stainless steel materials. The Brinell hardness test uses a load range of between 500 to 3,000kgf to cause an indentation using a ball indenter on a smooth surface. Additionally, the ball indenter is often 10mm in diameter and made of hardened steel with the 3,000kgf used for very hard metals, while smaller weights deal with softer materials. The hardness value obtained using the Brinell hardness test is often called the Brinell hardness number designated by HB. This Brinell number is obtained after dividing the applied force by the area of the material where there is an indentation.

 

  • Vickers Hardness Test

This test is often suitable for hard materials. It utilizes a diamond-tipped indenter which is in the form of a cone. The cone-shaped indenter presses into the material surface to cause an indentation which gives the Vickers hardness value upon measuring the width of the indentation. The load often varies but can be as high as 120kg, which makes it suitable for hardened stainless steel.

 

Conclusion

In conclusion, stainless steel can be versatile and beneficial for building components and manufacturing parts to resist corrosion. Nevertheless, the hardness of the stainless steel material is also of utmost importance to ensure that it can resist the impact of external force and maintain its durability. More importantly, the hardness testing for determining the hardness of stainless steel material is crucial since the different hardness tests have their merits and demerits and are also most suitable for different ranges of material hardness. Hence, you should carefully consider stainless steel materials the next time you contemplate using them in your design production.