DIN912 WITH KNURLING 12.9, ML40CR
DIN912 WITH KNURLING 12.9, ML40CR
(OP)
Hi every one. I am new to this forum. Has any one heard of a materail ML40CR ? A supplier from China has quoted us for Din 912 which are Socket Screws. These have to be grade 12,9. As far as I can see this material is suitable for 10,9. The supplier has said they heat it up and then it becomes 12,9? Is this possible and what would the drawbacks of using such a material be? These are really odd sizes and I have requested samples which I have sent for testing. I do not want to burn my fingers so I would like to have an experts opinion on whether it is possible to use this material. I have attached the certificate and here it is http://f iles.engin eering.com /getfile.a spx?folder =d5c90d4e- 158d-48f5- 9629-da53f 766d6f1&am p;file=DOC 111111.pdf
Please advise
Thanks
Please advise
Thanks





RE: DIN912 WITH KNURLING 12.9, ML40CR
RE: DIN912 WITH KNURLING 12.9, ML40CR
12.9 fasteners are also sensitive to hydrogen embrittlement so you may also want to perform a torque-tension test that your lab should be able to do.
RE: DIN912 WITH KNURLING 12.9, ML40CR
RE: DIN912 WITH KNURLING 12.9, ML40CR
Also, your material actually does not conform to ML40Cr. Your material is deficient in chrome (ML40Cr requires a minimum Cr content of 0.90%). You instead have an alloy conforming to 40Cr (0.80% - 1.10% Cr), which is identified in a variety of Chinese standards. However, I would not get too hung up on the original alloy. The important fact is that your cap screws are conforming to 12.9.
Aaron Tanzer
www.lehightesting.com