25CRMO4 is a high tensile grade of steel that contains chromium and molybdenum, and as a result this grade is often referred to as chromoly steel, chrome-moly, CrMo, CRMO, CR-MOLY.
It is similar to the American grade 4130 in terms of chemical and mechanical properties and is mainly used in the European industry sectors.
The material is not as easily weldable compared to other materials such as BS4 T45 to BS5 T100 or 15CDV6 (1.7734) as it requires pre and post weld heat treatment to avoid cold cracking. It is also unadvisable to weld Chromoly to other carbon steel grades due to the differences in chemical construction. It can be achieved, but particular attention to vital stress areas and heat affected zones must be made.
Examples of applications for 25CRMO4 include