4340 Chromoly Steel

4340 chromoly steel from OTAI, supply to top 500 company

What is the 4340 chromoly steel characteristic and application?

The 4340 chromoly steel has stability against overheating, but has high white point sensitivity, tempering brittleness, and poor weldability of steel. It needs high temperature preheating before welding and stress relief treatment after welding. Generally used in the quenched and tempered state, it can also be used as ultra high strength steel after low temperature tempering or isothermal quenching.

4340 chromoly steel is used to manufacture important quenched and tempered parts. That require good toughness, high strength and large size, such as heavy-duty shafts. It could bear high loads, steam turbine shafts and blades with a diameter greater than 250MM. It can also be used for rotor shafts and blades with operating temperatures exceeding 400 degrees. In addition, it can also be used to manufacture important parts with special performance requirements after nitriding treatment.

Heat treatment specifications: quenching at 850 ° C, oil cooling; tempering at 600 ° C, water cooling, oil cooling.

Few days ago, one customer asked me what material 4340 chromoly steel is. I explained to him that it belongs to the following CrNiMo series steel of the American Standards Association. It is mainly used in petroleum equipment. Above, the material is basically similar to the 40CrNiMo GB series of our national standard, but there are differences in composition. The main difference is in Ni. In China, many unscrupulous counterparts use 40CrNiMo instead of 4340 chromoly steel. From the points of standards, it is not workable to do like this. That is because 4340 steel is completely different in composition from 40CrNiMo. In addition, it is mainly used for petroleum equipment. If there is a problem with the material, it will cause great losses to the company. Therefore, if you are purchasing such steel material, it is necessary to find the professional and reliable supplier. Our OTAI specializes in exporting special steel to more than 30 countries in the world. We have rich and expert on this special steel field. The world ’s top 500 steel companies, Bohler also purchased the special steel from us.