Difference between ASTM A194 Grades 2H and 2HM
What makes 2HM different from 2H? Does the M stands for ‘Metric’? Although in many cases ‘M’ stands for Metric, in this case it is not so. Nuts of Grade 2H indicate that the alloy steel used for nut is quenched and tempered whereas in case of Grade 2HM the nuts are additionally tested 100% for hardness. Both these nuts can be manufactured by means of any of the processes - hot forging, cold forging or machining but the material must be heat treated. 2H heavy hex nuts are used in high temperature and high pressure services, with adequate strength and engineering to withstand extreme conditions. 2HM nuts are also produced in a similar way, yet have low proof load values and hardness. So, while 2H nuts can be substituted for 2HM but vice versa may not be true. The similarities and differences in these two grades are: Chemical composition of both grades 2H and 2HM is same. Refer https://nuboteck.blogspot.com/2020/05/api-20e-bolting-astm-a194.html The main difference i...