subject: free working (cutting, machining) steel

Reverting (referring, regarding, concerning, relating, in/with regard to) to our letter of/dated 12 inst.(instant/of the present month) we wonder (?regret not having received?) why we haven't received a reply (answer, response) from you, yet (to this day).

When (while) machining (processing) the trial shipment of free working (cutting, machining) steel we received on 18 inst (18th of the present month), we encountered (ran into; troubles occured, appeared, cropped up, came up, arose) serious (severe) problems (troubles, difficulties) because the physical properties (characteristics, features) of the material haven't met (haven't come up to, couldn't fulfil(l)) our fabrication (manufacturing) requirements. It is extremely difficult to process (machine) the free working (cutting, machining) steel and the service (working) life of the tools is very short at normal cutting speeds. We examined (analysed, scrutinized[under scrutiny]) the material as to (on) tensile strength, elongation, composition and structure and haven't found any satisfying (satisfactory) explanation. The extremely varying (variable) wear (and tear) of our cutting tools seems to be an indicator for (of) (points to, hints to, suggests, indicates) the fact that the steel in itself must be very non-uniform (inhomogeneous).

We would like to know now (We're interested in knowing), whether in regard to (regarding, in respect of) the long and ductile chips we specified too low a phosphorous content.

We are looking forward to your reply (answer) with great interest and remain,

with kind regards (yours sincerely, faithfully, sincerely, yours[official])