Difference between 42CrMo4 and 42CrMo

What’s The Difference Between 42CrMo And 42CrMo4

42CrMo is a kind of medium-carbon alloy structural steel with good comprehensive performance and good hardenability. It is often used to manufacture gear, connecting rod, high strength bolt and other important parts in machining process. The engineers often saw a material of 42CrMo4 mentioned in the European standard drawings. Is it be alternative with 42CrMo? What are the differences between them and their characteristics? We hereby discuss in depth from the terms of chemical analysis, mechanical properties and hardenabilit to find out the conclusion.

1. They come from different standards from different counties. 42crmo is the material in Chinese standard GB/T 3077, specification of alloy structural steel. The material of 42CrMo4 belong to EN 10083 series, hardened and tempered steel.

2. Chemical composition difference. There are tiny difference in content of element Si shown in the figure below, the Si content in 42CrMo is small than that in EN10083. In addition, according to GB3077, P and S content can be divided into three levels, while EN10083 only limits its maximum content.

Steel grades C Si Mn P max S max Cr Mo
42CrMo 0.38-0.45 0.17-0.37 0.5-0.8 0.035 0.035 0.9-1.2 0.15-0.25
42CrMo4 0.38-0.46 0.40 max 0.5-0.8 0.035 0.035 0.9-1.2 0.15-0.25
42CrMo quality levels P S
Quality 0.035 0.035
High quality 0.025 0.025
Super quality 0.025 0.015

2. Different hardenability requirements. The hardenability of GB3077 has no the specific value of the bandwidth of quenching. The buyer and the supplier may discuss a solution on their own if has special requirements. The specific value of hardened bandwidth is specified in EN10083, which is divided into three grades H,HL,HH for reference when ordering.

3. Different delivery condition. 42CrMo tubing is usually delivered in the condition of hot rolled and hot forging. If the customer needs the heat treatment condition (annealing, normal goods, high temperature tempering), it shall be specified in the contract. For EN10083 42CrMo4 tubing, there are five delivery conditions for choice: no heat treatment, heat treatment, softening annealing, quenching and high temperature tempering and other heat treatment.

4. Impact test requirements difference. When doing the impact test according to GB/T2975, 42CrMo sampling in the 1/4 of the outer diameter of the bar as the center of bar when diameter is greater than 50mm. When the diameter of the sample rod is 25mm, it shall be modulated according to the requirements of heat treatment process, and then the tensile test specimen shall be tested. In the EN10083 standard, the bar is first tempered in accordance with the recommended heat treatment. And when the sampling the bar which diameter is greater than 25mm, the sampling position should be centered 12mm around the outer diameter of the bar. In addition, 42CrMo uses the Charpy U-notch toughness, while the 42CrMo4 uses the charpy V testing. The two notch has the same depth but the different radius of the notch bottom(U type 1mm,v type 0.25mm).

From the analysis of the terms such as chemical composition, hardenability, mechanical properties, grain size and delivery condition of the two materials, we can conclude that the EN10083 standard is more strict and the testing requirements for mechanical properties are specified, which is convenient for the calculation of 42CrMo4 steel in actual us. More information bout 42CrMo4 steel pipe and 42CrMo4 bars, call for us or email inquiry@ab-steel.com

Posted in AISI 4140 42Crmo4 SCM440 Related.