3 Effects of Heat Treatment of Steel

First, Introduction

The effect of treatment varies due to the material and treatment method of the treated part. Even if the same material is treated with the same heat treatment method, the effect will be different due to the size and shape of the treated part. These influencing factors are collectively called effects, and there are three types of such effects.

Second, mass effect

Due to the size, that is, the mass of the treated part, the heat treatment results, especially the quenching results, are different, which is called the mass effect.

Usually, the thicker the diameter of the steel part, the harder it is to harden through; the thinner the diameter, the easier it is to harden through. The difference lies in the mass effect. The so-called large mass effect means that the heat treatment results caused by different masses are different. It means that the larger the part, the more difficult it is to quench. And the small mass effect, not to mention small parts, even large parts can be hardened through.

Carbon castings are an example of steel with a large mass effect, while chromium-molybdenum steel and nickel-chromium-molybdenum steel are examples of steel with a small mass effect. Due to the different sizes of parts, the different quenching effects are due to the mass effect; and due to different steel types, the different quenching effects are due to the hardenability. This is to analyze the quenching effect from different angles, and hardenability is to analyze the quenching effect from the perspective of the material of the steel.

Therefore, steel with good hardenability has a small mass effect and can be hardened even to large parts. In other words, it is the hardenability that can improve the mass effect. The alloy elements that effectively improve the hardenability include boron, manganese, molybdenum, chromium, etc.

Third, shape effect

The quenching effect is affected by the shape of the part.

Different shapes such as bars, plates, and balls have different quenching effects. In addition, even for the same treated parts, due to different quenching locations and different cooling methods, the quenching effect is also different. This influence caused by the shape of the part is the so-called shape effect.

The ratio of the cooling effect is 4:3:2 for the ball: round rod: and plate. The difference in cooling effect is that if the flat plate is 1, the 2-face angle is 3, the 3-face angle is 7, and the concave angle is 1/3.

Fourth, size effect

The mechanical properties of steel are not determined by the material alone. They change with the change of shape and size. Usually, the larger the size of steel, the lower the mechanical strength.

This change of mechanical properties with shape and size is called the size effect. The most prominent mechanical properties showing size effect are fatigue strength, tensile strength, and wear resistance. There is also a side effect, so it should also be paid attention to.